RE: Layer3 switch vs Router [7:7406]
This is actually covered in under the switching portion of the CCNP.. Here is a link from Cisco for you to reference: http://www.cisco.com/warp/public/cc/so/neso/lnso/cpso/l3c85_wp.htm Thanks, Mike Munoz -Original Message- From: Denton, Jason [mailto:[EMAIL PROTECTED]] Sent: Wednesday, June 06, 2001 3:35 PM To: [EMAIL PROTECTED] Subject: Layer3 switch vs Router [7:7406] Can anyone tell me what the REAL difference is between a layer3 switch and a router? Jason Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=7412&t=7406 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Layer3 switch vs Router [7:7406]
Layer 3 switch is a switch that by nature is a layer 2 device that has layer 3 (routing) capabilities such as cat6k w/MSM or MSFC, cat5k with RSM, and cat4k witk layer 3 module. Router is a layer 3 device which by nature is a layer 3. _ Get your FREE download of MSN Explorer at http://explorer.msn.com Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=7413&t=7406 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Layer3 switch vs Router [7:7406]
One differance is that a layer 3 switch does wire-speed switching ""Denton, Jason"" wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > Can anyone tell me what the REAL difference is between a layer3 switch and a > router? > > Jason Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=7415&t=7406 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Layer3 switch vs Router [7:7406]
Okay, two things - One - abduct a Cisco marketing rep, tie them to a chair, shine a bright, hot light in their face and ask *them* what the difference is. Two - while they're tied up, ask them what "wire-speed" is supposed to mean. - Original Message - From: Sam To: [EMAIL PROTECTED] Sent: Wednesday, June 06, 2001 4:27 PM Subject: Re: Layer3 switch vs Router [7:7406] One differance is that a layer 3 switch does wire-speed switching ""Denton, Jason"" wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > Can anyone tell me what the REAL difference is between a layer3 switch and a > router? > > Jason Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=7417&t=7406 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Layer3 switch vs Router [7:7406]
Well, Someone may have a product based answer for you but literally a router is a layer 3 switch. Just think of all of the functionality that a switch offers you and add on the route switch module to sweeten the pot. A router either bridges or has separate subnets on each of its interfaces.(simplistic answer of course). Bryan - Original Message - From: "Denton, Jason" To: Sent: Wednesday, June 06, 2001 3:35 PM Subject: Layer3 switch vs Router [7:7406] > Can anyone tell me what the REAL difference is between a layer3 switch and a > router? > > Jason Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=7422&t=7406 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Layer3 switch vs Router [7:7406]
Which means...? -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] On Behalf Of Sam Sent: Wednesday, June 06, 2001 1:28 PM To: [EMAIL PROTECTED] Subject:Re: Layer3 switch vs Router [7:7406] One differance is that a layer 3 switch does wire-speed switching ""Denton, Jason"" wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > Can anyone tell me what the REAL difference is between a layer3 switch and a > router? > > Jason Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=7426&t=7406 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Layer3 switch vs Router [7:7406]
I'm having trouble deciding - is this a smart ass remark? That link certainly makes it seem so. :-> Chuck -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] On Behalf Of Munoz, Michael Sent: Wednesday, June 06, 2001 1:17 PM To: [EMAIL PROTECTED] Subject: RE: Layer3 switch vs Router [7:7406] This is actually covered in under the switching portion of the CCNP.. Here is a link from Cisco for you to reference: http://www.cisco.com/warp/public/cc/so/neso/lnso/cpso/l3c85_wp.htm Thanks, Mike Munoz -Original Message- From: Denton, Jason [mailto:[EMAIL PROTECTED]] Sent: Wednesday, June 06, 2001 3:35 PM To: [EMAIL PROTECTED] Subject: Layer3 switch vs Router [7:7406] Can anyone tell me what the REAL difference is between a layer3 switch and a router? Jason Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=7427&t=7406 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Layer3 switch vs Router [7:7406]
Seriously? I did not mean to come across rudely.. I just took the switching recently which is why I mentioned the test. I also feel that url's are more useful than someone who just responds with a quick sentence. I feel that if you are going to respond to a technology question you should at least provide a link for them to read up on and to validate the answer. Thanks, Mike Munoz -Original Message- From: Chuck Larrieu [mailto:[EMAIL PROTECTED]] Sent: Wednesday, June 06, 2001 5:08 PM To: Munoz, Michael; [EMAIL PROTECTED] Subject: RE: Layer3 switch vs Router [7:7406] I'm having trouble deciding - is this a smart ass remark? That link certainly makes it seem so. :-> Chuck -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] On Behalf Of Munoz, Michael Sent: Wednesday, June 06, 2001 1:17 PM To: [EMAIL PROTECTED] Subject: RE: Layer3 switch vs Router [7:7406] This is actually covered in under the switching portion of the CCNP.. Here is a link from Cisco for you to reference: http://www.cisco.com/warp/public/cc/so/neso/lnso/cpso/l3c85_wp.htm Thanks, Mike Munoz -Original Message- From: Denton, Jason [mailto:[EMAIL PROTECTED]] Sent: Wednesday, June 06, 2001 3:35 PM To: [EMAIL PROTECTED] Subject: Layer3 switch vs Router [7:7406] Can anyone tell me what the REAL difference is between a layer3 switch and a router? Jason Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=7429&t=7406 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Layer3 switch vs Router [7:7406]
Price Jenn > >-Original Message- >From: Denton, Jason [mailto:[EMAIL PROTECTED]] >Sent: Wednesday, June 06, 2001 3:35 PM >To: [EMAIL PROTECTED] >Subject: Layer3 switch vs Router [7:7406] > > >Can anyone tell me what the REAL difference is between a layer3 switch and a >router? > >Jason Have a great day!! Jennifer Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=7430&t=7406 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Layer3 switch vs Router [7:7406]
Switches also have less latency than routers. Jenn > > >-Original Message- >From: Denton, Jason [mailto:[EMAIL PROTECTED]] >Sent: Wednesday, June 06, 2001 3:35 PM >To: [EMAIL PROTECTED] >Subject: Layer3 switch vs Router [7:7406] > > >Can anyone tell me what the REAL difference is between a layer3 switch and a >router? > >Jason Have a great day!! Jennifer Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=7431&t=7406 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Layer3 switch vs Router [7:7406]
Wire-speed means that routing decisions are made by using ASICs (application-specific integrated circuit) rather than software. What this translates to is more packets per second which means these Layer 3 switches can be used where high performance is critical. Another thing, I believe all of Cisco's L3 switches are non-blocking. ""Bradley J. Wilson"" wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > Okay, two things - > > One - abduct a Cisco marketing rep, tie them to a chair, shine a bright, hot > light in their face and ask *them* what the difference is. > > Two - while they're tied up, ask them what "wire-speed" is supposed to mean. > > > - Original Message - > From: Sam > To: [EMAIL PROTECTED] > Sent: Wednesday, June 06, 2001 4:27 PM > Subject: Re: Layer3 switch vs Router [7:7406] > > > One differance is that a layer 3 switch does wire-speed switching > > ""Denton, Jason"" wrote in message > [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > > Can anyone tell me what the REAL difference is between a layer3 switch and > a > > router? > > > > Jason Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=7432&t=7406 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Layer3 switch vs Router [7:7406]
Funny you mention this, I remember being in a Cisco marketing presentation a few years back, and getting very irritated at all the "wire speed switching" hype, and other claims that were being made as they tried to promote gige. I remember sitting there thinking, switches switch and routers route. That was of course before L3 switching monsters were firmly entrenched. Brian "Sonic" Whalen Success = Preparation + Opportunity On Wed, 6 Jun 2001, Bradley J. Wilson wrote: > Okay, two things - > > One - abduct a Cisco marketing rep, tie them to a chair, shine a bright, hot > light in their face and ask *them* what the difference is. > > Two - while they're tied up, ask them what "wire-speed" is supposed to mean. > > > - Original Message - > From: Sam > To: [EMAIL PROTECTED] > Sent: Wednesday, June 06, 2001 4:27 PM > Subject: Re: Layer3 switch vs Router [7:7406] > > > One differance is that a layer 3 switch does wire-speed switching > > ""Denton, Jason"" wrote in message > [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > > Can anyone tell me what the REAL difference is between a layer3 switch and > a > > router? > > > > Jason Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=7433&t=7406 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Layer3 switch vs Router [7:7406]
>From what I recall of the BCMSN exam, a true layer 3 switch does the job @ wire speed & uses hardware based (& not software) switching. Phil - Original Message - From: Jennifer Cribbs To: Sent: Wednesday, June 06, 2001 5:48 PM Subject: RE: Layer3 switch vs Router [7:7406] > Switches also have less latency than routers. > > Jenn > > > > > >-Original Message- > >From: Denton, Jason [mailto:[EMAIL PROTECTED]] > >Sent: Wednesday, June 06, 2001 3:35 PM > >To: [EMAIL PROTECTED] > >Subject: Layer3 switch vs Router [7:7406] > > > > > >Can anyone tell me what the REAL difference is between a layer3 switch and a > >router? > > > >Jason > Have a great day!! > Jennifer Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=7436&t=7406 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Layer3 switch vs Router [7:7406]
A layer 3 switch, as a previous poster said, is a switch, that has a route processor (or that can connect to an external router), to perform Layer 3 functions "at wire speed". But it also has ASICs that performs other functions that a normal Layer 2 switch doesn't have (as you'll see below). "At wire speed" is a fancy way of waying "as fast as a switch normally switches traffic". In the below section, MLS-SE = Multilayer Switching Engine and MLS-RP = Multilayer Route Processor. This is not a mystery nor is it some special voodoo. it's actually an ingenious process 1) A frame (ethernet let's say) containing an IP packet comes into a switch port 2) The MLS-SE actually looks at the Layer 3 information (source/destination IPs and port numbers) and looks in the MLS cache to see if there is already an entry for this "flow" (a flow is a single unidirectional conversation between the source/destination IPs and port #s) 3) If there is not an MLS cache entry, the MLS-SE makes a partial MLS cache entry using the source/destination IP and port #s and sends the packet to the MLS-RP (which could be an external router also) 4) The MLS-RP then routes the packet normally and hands the packet with the rewritten Layer 2 info back to the MLS-SE. 5) The MLS-SE looks in the CAM table to find the port to reach the destination MAC, uses that information to complete the MLS cache entry with the proper switch port number, and forwards the packet out the destination switch port. Now for every subsequent packet in that flow (with the same source/destination IP and port info), the MLS-SE (in step 2 above) will find the MLS cache entry, rewrite the Layer 2 info, just as if the packet had been routed by the MLS-RP, and spits it out the destination port. A Layer 3 switch differs from a regular Layer 2 switch (or even a router) because it can perfom this "MLS cache lookup and Layer 2 rewrite" on the fly without delaying the packet anymore than a normal switch, so therefore it's called wirespeed. The NetFlow Feature Card (NFFC) or NFFC 2 is the hardware that performs this MLS cache and flow comparison. Keep in mind, that a flow is unidirectional. So if 2 computers are communicating back and forth, the switch will actually have 2 MLS entries (2 flows), one for the conversation going in each direction. The easy way to remember how a Layer 3 switch (Multilayer switch) works is: "Route once, switch many" It's actually a smoking idea that allows switches to take a great burden from the routers having to route EVERY SINGLE PACKET, as well as giving the appearance that this "routing" (which is truly being bypassed after the first packet) is happening at wirespeed. Kudos to whomever thought this up! Here's a great explanation of Layer 3 switching, flows, etc from Cisco: http://www.cisco.com/univercd/cc/td/doc/product/lan/cat5000/rel_5_2/layer3/m ls.htm Mike W. "Denton, Jason" wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > Can anyone tell me what the REAL difference is between a layer3 switch and a > router? > > Jason Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=7434&t=7406 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Layer3 switch vs Router [7:7406]
Bryan is correct. Also there is the issue of cost. Many organizations are not willing to spend a great deal on a router when they can get the same functionality in switch. -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Bryan In Richmond Sent: Wednesday, June 06, 2001 4:01 PM To: [EMAIL PROTECTED] Subject: Re: Layer3 switch vs Router [7:7406] Well, Someone may have a product based answer for you but literally a router is a layer 3 switch. Just think of all of the functionality that a switch offers you and add on the route switch module to sweeten the pot. A router either bridges or has separate subnets on each of its interfaces.(simplistic answer of course). Bryan - Original Message - From: "Denton, Jason" To: Sent: Wednesday, June 06, 2001 3:35 PM Subject: Layer3 switch vs Router [7:7406] > Can anyone tell me what the REAL difference is between a layer3 switch and a > router? > > Jason Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=7439&t=7406 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Layer3 switch vs Router [7:7406]
That is a great answer!! That is above and beyond the call of duty and I am printing this and keeping it for future ref. Seriously. That is exactly why I like this group. Thanks, Jennifer Cribbs 6/6/2001 5:09:37 PM, "Michael L. Williams" wrote: >A layer 3 switch, as a previous poster said, is a switch, that has a route >processor (or that can connect to an external router), to perform Layer 3 >functions "at wire speed". But it also has ASICs that performs other >functions that a normal Layer 2 switch doesn't have (as you'll see below). > >"At wire speed" is a fancy way of waying "as fast as a switch normally >switches traffic". > >In the below section, MLS-SE = Multilayer Switching Engine and MLS-RP = >Multilayer Route Processor. > >This is not a mystery nor is it some special voodoo. it's actually an >ingenious process > >1) A frame (ethernet let's say) containing an IP packet comes into a switch >port >2) The MLS-SE actually looks at the Layer 3 information (source/destination >IPs and port numbers) and looks in the MLS cache to see if there is already >an entry for this "flow" (a flow is a single unidirectional conversation >between the source/destination IPs and port #s) >3) If there is not an MLS cache entry, the MLS-SE makes a partial MLS cache >entry using the source/destination IP and port #s and sends the packet to >the MLS-RP (which could be an external router also) >4) The MLS-RP then routes the packet normally and hands the packet with the >rewritten Layer 2 info back to the MLS-SE. >5) The MLS-SE looks in the CAM table to find the port to reach the >destination MAC, uses that information to complete the MLS cache entry with >the proper switch port number, and forwards the packet out the destination >switch port. > >Now for every subsequent packet in that flow (with the same >source/destination IP and port info), the MLS-SE (in step 2 above) will find >the MLS cache entry, rewrite the Layer 2 info, just as if the packet had >been routed by the MLS-RP, and spits it out the destination port. A Layer 3 >switch differs from a regular Layer 2 switch (or even a router) because it >can perfom this "MLS cache lookup and Layer 2 rewrite" on the fly without >delaying the packet anymore than a normal switch, so therefore it's called >wirespeed. The NetFlow Feature Card (NFFC) or NFFC 2 is the hardware that >performs this MLS cache and flow comparison. > >Keep in mind, that a flow is unidirectional. So if 2 computers are >communicating back and forth, the switch will actually have 2 MLS entries (2 >flows), one for the conversation going in each direction. > >The easy way to remember how a Layer 3 switch (Multilayer switch) works is: >"Route once, switch many" > >It's actually a smoking idea that allows switches to take a great burden >from the routers having to route EVERY SINGLE PACKET, as well as giving the >appearance that this "routing" (which is truly being bypassed after the >first packet) is happening at wirespeed. Kudos to whomever thought this up! > >Here's a great explanation of Layer 3 switching, flows, etc from Cisco: > >http://www.cisco.com/univercd/cc/td/doc/product/lan/cat5000/rel_5_2/layer3/m >ls.htm > >Mike W. > >"Denton, Jason" wrote in message >[EMAIL PROTECTED]">news:[EMAIL PROTECTED]... >> Can anyone tell me what the REAL difference is between a layer3 switch and >a >> router? >> >> Jason Have a great day!! Jennifer Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=7443&t=7406 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Layer3 switch vs Router [7:7406]
For the record: Layer 3 switch = Multilayer switch (I say this because I like to use the term Multilayer switch rather than Layer 3 switch... dunno why... I guess because in the switch/routers, you actually use and configure Multilayer switching) In reply to some of the other posts on this topic: >This is actually covered in under the switching portion of the CCNP.. >Here is a link from Cisco for you to reference: >http://www.cisco.com/warp/public/cc/so/neso/lnso/cpso/l3c85_wp.htm Layer 3 switching (Multilayer switching) *is* covered on the CCNP Switching exam and I don't know how one could pass it without an understanding of how it works. (although that link that was provided pointed to a page that didn't explain MLS very well at all) > One differance is that a layer 3 switch does wire-speed switching AFAIK, *all* switches perform wire-speed switching, as long as the backplane isn't oversubscribed (even then what gets switched is done at wirespeed and other stuff is dropped). Can someone make sure I'm not fibbing or confused on this? >Okay, two things - > >One - abduct a Cisco marketing rep, tie them to a chair, shine a bright, hot >light in their face and ask *them* what the difference is. > >Two - while they're tied up, ask them what "wire-speed" is supposed to mean. Wire-speed simply means that the data is switched across the backplane to the destination port ASAP, as fast as the wires can carry the data thru the ASICs and to the destination port. I.E. the speed of light (minus a small fraction because the wires do actually have a non-zero resistance =) >Someone may have a product based answer for you but literally a router is a >layer 3 switch. Just think of all of the functionality that a switch offers >you and add on the route switch module to sweeten the pot. >A router either bridges or has separate subnets on each of its >interfaces.(simplistic answer of course). This is very misleading. Although a router has a switching process within it, and that switching process can take on many forms, a router is NOT simply a Layer 3 switch. Although a router can bridge (including bridging VLANS using Integrated Routing and Bridging), even then it is not the equivalent to a switch because of the way it performs the process (in software on a CPU instead of with an ASIC). The router doesn't keep a CAM table like a switch, etc. and without something like a NetFlow Feature Card or MLS processor, a router can't bridge (switch) at wirespeed like a true Layer 2 switch.. Even on a switch/router with a NFFC or the like, without Multilayer switching enabled, it's like a router with a ton of ethernet (or whatever) interfaces. The packets are NOT routed and forwarded out at wirespeed like they are (after the first packet) when Multilayer switching is enabled and configured. I by no means am the expert on Multilayer switching, and I'm not trying to flame anyone for their answers. But there were alot of things being said that didn't answer the original poster's question (actually the one post by Bob Salazar was correct, but he didn't mention that you have to actually turn on the Multilayer switching fuctions on the hardware he listed) or that were misleading. I'm sure there are some things that I messed up or just don't have a full understanding of (like "wire-speed hehe), so comments are welcome. Mike W. "Denton, Jason" wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > Can anyone tell me what the REAL difference is between a layer3 switch and a > router? > > Jason Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=7441&t=7406 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Layer3 switch vs Router [7:7406]
Unless one uses layer 4 ACLs... ""Sam"" wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > Wire-speed means that routing decisions are made by using ASICs > (application-specific integrated circuit) rather than software. What this > translates to is more packets per second which means these Layer 3 switches > can be used where high performance is critical. > > Another thing, I believe all of Cisco's L3 switches are non-blocking. > > ""Bradley J. Wilson"" wrote in message > [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > > Okay, two things - > > > > One - abduct a Cisco marketing rep, tie them to a chair, shine a bright, > hot > > light in their face and ask *them* what the difference is. > > > > Two - while they're tied up, ask them what "wire-speed" is supposed to > mean. > > > > > > - Original Message - > > From: Sam > > To: [EMAIL PROTECTED] > > Sent: Wednesday, June 06, 2001 4:27 PM > > Subject: Re: Layer3 switch vs Router [7:7406] > > > > > > One differance is that a layer 3 switch does wire-speed switching > > > > ""Denton, Jason"" wrote in message > > [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > > > Can anyone tell me what the REAL difference is between a layer3 switch > and > > a > > > router? > > > > > > Jason Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=7452&t=7406 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Layer3 switch vs Router [7:7406]
I browsed the article you provided. It struck me as vague, lacking in real detail, and generally geared for folks who don't spend a lot of time looking at technical details. My comment was meant to be humorous, but apparently I failed (again). Note to myself - give up any and all dreams about being a night club comic. Chuck -Original Message- From: Munoz, Michael [mailto:[EMAIL PROTECTED]] Sent: Wednesday, June 06, 2001 2:26 PM To: 'Chuck Larrieu'; [EMAIL PROTECTED] Subject: RE: Layer3 switch vs Router [7:7406] Seriously? I did not mean to come across rudely.. I just took the switching recently which is why I mentioned the test. I also feel that url's are more useful than someone who just responds with a quick sentence. I feel that if you are going to respond to a technology question you should at least provide a link for them to read up on and to validate the answer. Thanks, Mike Munoz -Original Message- From: Chuck Larrieu [mailto:[EMAIL PROTECTED]] Sent: Wednesday, June 06, 2001 5:08 PM To: Munoz, Michael; [EMAIL PROTECTED] Subject: RE: Layer3 switch vs Router [7:7406] I'm having trouble deciding - is this a smart ass remark? That link certainly makes it seem so. :-> Chuck -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] On Behalf Of Munoz, Michael Sent: Wednesday, June 06, 2001 1:17 PM To: [EMAIL PROTECTED] Subject: RE: Layer3 switch vs Router [7:7406] This is actually covered in under the switching portion of the CCNP.. Here is a link from Cisco for you to reference: http://www.cisco.com/warp/public/cc/so/neso/lnso/cpso/l3c85_wp.htm Thanks, Mike Munoz -Original Message- From: Denton, Jason [mailto:[EMAIL PROTECTED]] Sent: Wednesday, June 06, 2001 3:35 PM To: [EMAIL PROTECTED] Subject: Layer3 switch vs Router [7:7406] Can anyone tell me what the REAL difference is between a layer3 switch and a router? Jason Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=7453&t=7406 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Layer3 switch vs Router [7:7406]
Sergei.. please elaborate. If you use a layer 4 ACL, the switches are no longer non-blocking? Or are you refering to using a layer 4 ACL on a layer 3 switch? tell me more Mike W. "Sergei" wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > Unless one uses layer 4 ACLs... > ""Sam"" wrote in message > [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > > Wire-speed means that routing decisions are made by using ASICs > > (application-specific integrated circuit) rather than software. What this > > translates to is more packets per second which means these Layer 3 > switches > > can be used where high performance is critical. > > > > Another thing, I believe all of Cisco's L3 switches are non-blocking. > > > > ""Bradley J. Wilson"" wrote in message > > [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > > > Okay, two things - > > > > > > One - abduct a Cisco marketing rep, tie them to a chair, shine a bright, > > hot > > > light in their face and ask *them* what the difference is. > > > > > > Two - while they're tied up, ask them what "wire-speed" is supposed to > > mean. > > > > > > > > > - Original Message - > > > From: Sam > > > To: [EMAIL PROTECTED] > > > Sent: Wednesday, June 06, 2001 4:27 PM > > > Subject: Re: Layer3 switch vs Router [7:7406] > > > > > > > > > One differance is that a layer 3 switch does wire-speed switching > > > > > > ""Denton, Jason"" wrote in message > > > [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > > > > Can anyone tell me what the REAL difference is between a layer3 switch > > and > > > a > > > > router? > > > > > > > > Jason Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=7461&t=7406 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Layer3 switch vs Router [7:7406]
Very good, and thanks. But... to quote a sage, who made this point last time this topic came up, what exactly is the difference between a router that routes 100,000 packets per second, and a layer three switch that switches 100,000 packets per second? Cisco can talk about ASIC's versus processors all they want. Both are chips. High end routers also have ASIC's as well as other means to optimize traffic flow. Truth be told, layer 3 switch is a marketing concept, plain and simple. Chuck -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] On Behalf Of Michael L. Williams Sent: Wednesday, June 06, 2001 3:56 PM To: [EMAIL PROTECTED] Subject: Re: Layer3 switch vs Router [7:7406] For the record: Layer 3 switch = Multilayer switch (I say this because I like to use the term Multilayer switch rather than Layer 3 switch... dunno why... I guess because in the switch/routers, you actually use and configure Multilayer switching) In reply to some of the other posts on this topic: >This is actually covered in under the switching portion of the CCNP.. >Here is a link from Cisco for you to reference: >http://www.cisco.com/warp/public/cc/so/neso/lnso/cpso/l3c85_wp.htm Layer 3 switching (Multilayer switching) *is* covered on the CCNP Switching exam and I don't know how one could pass it without an understanding of how it works. (although that link that was provided pointed to a page that didn't explain MLS very well at all) > One differance is that a layer 3 switch does wire-speed switching AFAIK, *all* switches perform wire-speed switching, as long as the backplane isn't oversubscribed (even then what gets switched is done at wirespeed and other stuff is dropped). Can someone make sure I'm not fibbing or confused on this? >Okay, two things - > >One - abduct a Cisco marketing rep, tie them to a chair, shine a bright, hot >light in their face and ask *them* what the difference is. > >Two - while they're tied up, ask them what "wire-speed" is supposed to mean. Wire-speed simply means that the data is switched across the backplane to the destination port ASAP, as fast as the wires can carry the data thru the ASICs and to the destination port. I.E. the speed of light (minus a small fraction because the wires do actually have a non-zero resistance =) >Someone may have a product based answer for you but literally a router is a >layer 3 switch. Just think of all of the functionality that a switch offers >you and add on the route switch module to sweeten the pot. >A router either bridges or has separate subnets on each of its >interfaces.(simplistic answer of course). This is very misleading. Although a router has a switching process within it, and that switching process can take on many forms, a router is NOT simply a Layer 3 switch. Although a router can bridge (including bridging VLANS using Integrated Routing and Bridging), even then it is not the equivalent to a switch because of the way it performs the process (in software on a CPU instead of with an ASIC). The router doesn't keep a CAM table like a switch, etc. and without something like a NetFlow Feature Card or MLS processor, a router can't bridge (switch) at wirespeed like a true Layer 2 switch.. Even on a switch/router with a NFFC or the like, without Multilayer switching enabled, it's like a router with a ton of ethernet (or whatever) interfaces. The packets are NOT routed and forwarded out at wirespeed like they are (after the first packet) when Multilayer switching is enabled and configured. I by no means am the expert on Multilayer switching, and I'm not trying to flame anyone for their answers. But there were alot of things being said that didn't answer the original poster's question (actually the one post by Bob Salazar was correct, but he didn't mention that you have to actually turn on the Multilayer switching fuctions on the hardware he listed) or that were misleading. I'm sure there are some things that I messed up or just don't have a full understanding of (like "wire-speed hehe), so comments are welcome. Mike W. "Denton, Jason" wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > Can anyone tell me what the REAL difference is between a layer3 switch and a > router? > > Jason Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=7465&t=7406 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Layer3 switch vs Router [7:7406]
Aw, come on Chuck. I was hoping to see you headline at the Comedy Club here in Las Vegas someday. :) Prof. Tom Lisa, CCAI Community College of Southern Nevada Cisco Regional Networking Academy Chuck Larrieu wrote: > I browsed the article you provided. It struck me as vague, lacking in real > detail, and generally geared for folks who don't spend a lot of time looking > at technical details. > > My comment was meant to be humorous, but apparently I failed (again). Note > to myself - give up any and all dreams about being a night club comic. > > Chuck > > -Original Message- > From: Munoz, Michael [mailto:[EMAIL PROTECTED]] > Sent: Wednesday, June 06, 2001 2:26 PM > To: 'Chuck Larrieu'; [EMAIL PROTECTED] > Subject:RE: Layer3 switch vs Router [7:7406] > > Seriously? I did not mean to come across rudely.. I just took the > switching recently which is why I mentioned the test. > > I also feel that url's are more useful than someone who just responds with a > quick sentence. I feel that if you are going to respond to a technology > question you should at least provide a link for them to read up on and to > validate the answer. > > Thanks, > > Mike Munoz > > -Original Message- > From: Chuck Larrieu [mailto:[EMAIL PROTECTED]] > Sent: Wednesday, June 06, 2001 5:08 PM > To: Munoz, Michael; [EMAIL PROTECTED] > Subject: RE: Layer3 switch vs Router [7:7406] > > I'm having trouble deciding - is this a smart ass remark? That link > certainly makes it seem so. :-> > > Chuck > > -Original Message- > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] On Behalf Of > Munoz, Michael > Sent: Wednesday, June 06, 2001 1:17 PM > To: [EMAIL PROTECTED] > Subject:RE: Layer3 switch vs Router [7:7406] > > This is actually covered in under the switching portion of the CCNP.. > > Here is a link from Cisco for you to reference: > > http://www.cisco.com/warp/public/cc/so/neso/lnso/cpso/l3c85_wp.htm > > Thanks, > > Mike Munoz > > -Original Message- > From: Denton, Jason [mailto:[EMAIL PROTECTED]] > Sent: Wednesday, June 06, 2001 3:35 PM > To: [EMAIL PROTECTED] > Subject: Layer3 switch vs Router [7:7406] > > Can anyone tell me what the REAL difference is between a layer3 switch and a > router? > > Jason Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=7467&t=7406 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Layer3 switch vs Router [7:7406]
True, routers can handle a 100,000 packets per second. According to Cisco Layer 3 switches handle millions of packets per second. ""Denton, Jason"" wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > Can anyone tell me what the REAL difference is between a layer3 switch and a > router? > > Jason Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=7468&t=7406 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Layer3 switch vs Router [7:7406]
Speed. Actually, that's the answer a 3Com engineer gave me when I asked him that very question. TTFN, Bill in Anchorage -Original Message- From: Denton, Jason [mailto:[EMAIL PROTECTED]] Sent: Wednesday, June 06, 2001 11:35 AM To: [EMAIL PROTECTED] Subject: Layer3 switch vs Router [7:7406] Can anyone tell me what the REAL difference is between a layer3 switch and a router? Jason Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=7471&t=7406 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Layer3 switch vs Router [7:7406]
"Michael L. Williams" wrote: > > Sergei.. please elaborate. If you use a layer 4 ACL, the switches > are no longer non-blocking? Or are you refering to using a layer 4 ACL on a > layer 3 switch? tell me more > > Mike W. > > "Sergei" wrote in message > [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > > Unless one uses layer 4 ACLs... > > ""Sam"" wrote in message > > [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > > > Wire-speed means that routing decisions are made by using ASICs > > > (application-specific integrated circuit) rather than software. What > this > > > translates to is more packets per second which means these Layer 3 > > switches > > > can be used where high performance is critical. > > > > > > Another thing, I believe all of Cisco's L3 switches are non-blocking. > > > > > > ""Bradley J. Wilson"" wrote in message > > > [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > > > > Okay, two things - > > > > > > > > One - abduct a Cisco marketing rep, tie them to a chair, shine a > bright, > > > hot > > > > light in their face and ask *them* what the difference is. > > > > > > > > Two - while they're tied up, ask them what "wire-speed" is supposed to > > > mean. > > > > > > > > > > > > - Original Message - > > > > From: Sam > > > > To: [EMAIL PROTECTED] > > > > Sent: Wednesday, June 06, 2001 4:27 PM > > > > Subject: Re: Layer3 switch vs Router [7:7406] > > > > > > > > > > > > One differance is that a layer 3 switch does wire-speed switching > > > > > > > > ""Denton, Jason"" wrote in message > > > > [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > > > > > Can anyone tell me what the REAL difference is between a layer3 > switch > > > and > > > > a > > > > > router? > > > > > > > > > > Jason I am sorry, should have said some thing meaningful. :( hypothetically speaking, if the ACLs are in place, wire speed is gone. The concept route one switch many is no longer holds its value. Anyhow, let routers do what they do best, and allow switches do their layer 2 stuff... Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=7473&t=7406 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Layer3 switch vs Router [7:7406]
"Sergei Gearasimtchouk" wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > I am sorry, should have said some thing meaningful. :( > hypothetically speaking, if the ACLs are in place, wire speed is gone. > The concept route one switch many is no longer holds its value. That's what I thought you meant. I'm glad you clarified your position. But it's incorrect. Multilayer switching (& therefore wire speed "routing") are out the door only when you have an ACL applied to the MLS-RP interface as an incoming ACL. That's it. This is where flow masks come into play. There are 4 situations that need to be considered when using ACLs and Multilayer switching: 1) Where there is an incoming ACL on the MLS-RP interface, Multilayer switching is out the window because every incoming packet must be examined by the router. 2) If there is no access list, you can use a Destination IP flow mask, the simplest of the flow masks, where only the destination IP address is looked for in the MLS cache. 3) When there is a outgoing standard IP ACL applied to the MLS-RP interface, a Source-Destination IP flow mask needs to be used. This forces the MLS-SE to look for an entry with both the source and destination IP addresses in the MLS cache. Here's the reason why: If a packet has been sent from the MLS-SE to the MLS-RP, the packet gets routed, then the outgoing ACL is applied. If the packet makes it back to the MLS-SE, then the MLS-SE knows that the packet was allowed (not denied by the ACL) and it makes a MLS cache entry. Since a standard IP ACL uses source IP to permit/deny, the MLS-SE needs to look for the source IP as well as the destination IP in the MLS cache. Any subsequent packets from/to the same source/destination need not be compared to the ACL again as the criteria for the ACL on the original packet was satisfied. 4) When there is an outgoing extended IP ACL applied to the MLS-RP interface, an IP Flow mask needs to be used. An IP Flow masks instructs the MLS-SE to look for an entry that contains the source IP and port AND destination IP and port (basically Layers 3 AND 4). The MLS-SE must look for all of that information in the MLS cache because extended IP ACLs permit/deny using all of those criteria. Again, the same reasoning applies as far as the ACL goes, which is: if the first packet sent to the MLS-RP comes back to the MLS-SE, then the MLS-SE knows that the packet was allowed (not denied) by the ACL, and therefore it doesn't need to check the ACL for subsequent packet and Multilayer switching continues as normal. Most of the time an incoming ACL can be re-written as an outgoing ACL on other interfaces. Although it is usually recommended to use incoming ACLs over outgoing ACLs (so that traffic unwanted traffic doesn't get into the router's fabric just to be denied going out of another interface), in the case of Multilayer switching, the disadvantages caused by using outgoing ACLs are completely outweighed by the advantage of being able to use Multilayer switching. So, even with an ACL active, as long as it's an outgoing ACL on the MLS-RP interface, "wire speed routing" is still in tact. > Anyhow, let routers do what they do best, and allow switches do their > layer 2 stuff... Multilayer switching is an ingenious idea that allows a switch to take an incredible load off of the routers while not only providing the same performance, but providing better, faster performance. As another post mentioned, sure a router can do 100,000 packets/sec, but multilayer switches can handle an order of magnitude more traffic (in the millions of packets/sec) Mike W. Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=7483&t=7406 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Layer3 switch vs Router [7:7406]
Chuck.. I talked to a good friend of mine that knows more of this than I do.. and even HE wasn't clear on the line of switch -vs- router. so my following comments are strickly my thinking out loud.. mostly to get feedback . I don't think there is a difference in a layer 3 switch that does 100,000 packets/sec -vs- a router that does 100,000 packets/sec. However, respectfully submit that I don't know of any routers that can keep up with Layer 3 switches because in multilayer switching the route processor only has to route the first packet in a flow. At that point everything is switched as fast as the switch can switch them (tounge twister), and even the fastest routers would have trouble routing as speeds that switches can switch at. IMHO, any switch-router that can do 100,000 packets/sec can't reach it full potential unless Multilayer switching is enabled and configured. Further, I submit that there isn't a router that can handle the throughput of a switch-router utilizing Multilayer switching. With switch backplanes reaching 32 to 256Gbps, I don't know of a pure layer 3 router than can keep up with this pace without using MLS. I disagree with the assertion that ASICs and processor are equal because they're both chips. Obviously we could compare the P4 chip to the 486 chip and see that not all chips are equal. And I realize that's not what you are claiming. =) However, there is a distict difference between a general purpose CPU and an ASIC and how fast they can do a specific job. General purpose CPUs have instruction sets and need to be programmed with code. ASICs are indeed chips, but they are chips whose entire circuitry is designed and dedicated to do one thing and one thing only. This give the ASIC a definite advantage over any general purpose CPU on a give task. Yes, I hate to make blanket statements because there are things like the speed of the respective CPUs, etc. But it is generally accepted that an ASIC performs a given task much faster than a general purpose CPU. That's why 3D graphics cards use specific processors (ASICs) instead of just another P3 on the video card, etc.. Utilizing ASICs allows things like checking for MLS cache entries and rewriting Layer 2 info, etc "at wirespeed". I can't say 100%, but I believe this means that it can output a "routed" packet (assuming it's in the MLS cache) in a single "cycle". I know know if that's the correct terminology, but my point being that an ASIC is able to do this type of thing. A general purpose CPU running IOS code, etc would take many clock cycles to perform the same type operations and it's speed can't compare to an ASIC. I have to say though, that I'm not all that familiar with the top end routers (switch-routers, whatever) like the 12000 GSRs (or the new 10Gig SRs), etc. so perhaps they have some ASICs to perform their routing.. dunno. My 2 cents.. Mike W. "Chuck Larrieu" wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > Very good, and thanks. > > But... to quote a sage, who made this point last time this topic came up, > what exactly is the difference between a router that routes 100,000 packets > per second, and a layer three switch that switches 100,000 packets per > second? > > Cisco can talk about ASIC's versus processors all they want. Both are chips. > High end routers also have ASIC's as well as other means to optimize traffic > flow. > > Truth be told, layer 3 switch is a marketing concept, plain and simple. > > Chuck > > -Original Message- > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] On Behalf Of > Michael L. Williams > Sent: Wednesday, June 06, 2001 3:56 PM > To: [EMAIL PROTECTED] > Subject: Re: Layer3 switch vs Router [7:7406] > > For the record: Layer 3 switch = Multilayer switch (I say this because I > like to use the term Multilayer switch rather than Layer 3 switch... dunno > why... I guess because in the switch/routers, you actually use and configure > Multilayer switching) > > In reply to some of the other posts on this topic: > > >This is actually covered in under the switching portion of the CCNP.. > >Here is a link from Cisco for you to reference: > >http://www.cisco.com/warp/public/cc/so/neso/lnso/cpso/l3c85_wp.htm > > Layer 3 switching (Multilayer switching) *is* covered on the CCNP Switching > exam and I don't know how one could pass it without an understanding of how > it works. (although that link that was provided pointed to a page that > didn't explain MLS very well at all) > > > One differance is that a layer 3 switch does wire-speed switching > > AFAIK, *all* switches perform wire-speed switching, as long as the backplane > is
RE: Layer3 switch vs Router [7:7406]
So layer three switches are faster, 'eh? By orders of magnitude, 'eh? This calls for a bit of research on CCO. Hhhmmm Catalyst 8500 = 24 million PPS http://www.cisco.com/univercd/cc/td/doc/pcat/ca8500c.htm#CJAEJHDF Catalyst 6509 = 170 million PPS http://www.cisco.com/univercd/cc/td/doc/pcat/ca6000.htm Cisco 12000 = 375 million PPS http://www.cisco.com/univercd/cc/td/doc/pcat/12000.htm Cisco 7600 - 30 million PPS http://www.cisco.com/univercd/cc/td/doc/pcat/7600.htm so it would appear, based on Cisco's own product literature, that high end router versus high end switch, the edge most definitely goes to the product Cisco calls a router. and numbers are all over the place, to judge from the example I have looked at. Look, my point remains that any trickery, hardware or otherwise, can be applied to "routers" as well as "switches". It most definitely is NOT enough to say that there is a difference and it is because of the hardware construction of a "switch" versus that of a "router" Chuck -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] On Behalf Of Michael L. Williams Sent: Wednesday, June 06, 2001 8:52 PM To: [EMAIL PROTECTED] Subject:Re: Layer3 switch vs Router [7:7406] "Sergei Gearasimtchouk" wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > I am sorry, should have said some thing meaningful. :( > hypothetically speaking, if the ACLs are in place, wire speed is gone. > The concept route one switch many is no longer holds its value. That's what I thought you meant. I'm glad you clarified your position. But it's incorrect. Multilayer switching (& therefore wire speed "routing") are out the door only when you have an ACL applied to the MLS-RP interface as an incoming ACL. That's it. This is where flow masks come into play. There are 4 situations that need to be considered when using ACLs and Multilayer switching: 1) Where there is an incoming ACL on the MLS-RP interface, Multilayer switching is out the window because every incoming packet must be examined by the router. 2) If there is no access list, you can use a Destination IP flow mask, the simplest of the flow masks, where only the destination IP address is looked for in the MLS cache. 3) When there is a outgoing standard IP ACL applied to the MLS-RP interface, a Source-Destination IP flow mask needs to be used. This forces the MLS-SE to look for an entry with both the source and destination IP addresses in the MLS cache. Here's the reason why: If a packet has been sent from the MLS-SE to the MLS-RP, the packet gets routed, then the outgoing ACL is applied. If the packet makes it back to the MLS-SE, then the MLS-SE knows that the packet was allowed (not denied by the ACL) and it makes a MLS cache entry. Since a standard IP ACL uses source IP to permit/deny, the MLS-SE needs to look for the source IP as well as the destination IP in the MLS cache. Any subsequent packets from/to the same source/destination need not be compared to the ACL again as the criteria for the ACL on the original packet was satisfied. 4) When there is an outgoing extended IP ACL applied to the MLS-RP interface, an IP Flow mask needs to be used. An IP Flow masks instructs the MLS-SE to look for an entry that contains the source IP and port AND destination IP and port (basically Layers 3 AND 4). The MLS-SE must look for all of that information in the MLS cache because extended IP ACLs permit/deny using all of those criteria. Again, the same reasoning applies as far as the ACL goes, which is: if the first packet sent to the MLS-RP comes back to the MLS-SE, then the MLS-SE knows that the packet was allowed (not denied) by the ACL, and therefore it doesn't need to check the ACL for subsequent packet and Multilayer switching continues as normal. Most of the time an incoming ACL can be re-written as an outgoing ACL on other interfaces. Although it is usually recommended to use incoming ACLs over outgoing ACLs (so that traffic unwanted traffic doesn't get into the router's fabric just to be denied going out of another interface), in the case of Multilayer switching, the disadvantages caused by using outgoing ACLs are completely outweighed by the advantage of being able to use Multilayer switching. So, even with an ACL active, as long as it's an outgoing ACL on the MLS-RP interface, "wire speed routing" is still in tact. > Anyhow, let routers do what they do best, and allow switches do their > layer 2 stuff... Multilayer switching is an ingenious idea that allows a switch to take an incredible load off of the routers while not only providing the same performance, but providing better, faster performance. As another post mentioned, sure a router can do 100,000 packets/sec, but multilayer switches can handle
RE: Layer3 switch vs Router [7:7406]
Got a link to substantiate that claim? -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] On Behalf Of Sam Sent: Wednesday, June 06, 2001 6:13 PM To: [EMAIL PROTECTED] Subject:Re: Layer3 switch vs Router [7:7406] True, routers can handle a 100,000 packets per second. According to Cisco Layer 3 switches handle millions of packets per second. ""Denton, Jason"" wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > Can anyone tell me what the REAL difference is between a layer3 switch and a > router? > > Jason Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=7487&t=7406 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Layer3 switch vs Router [7:7406]
cisco also has this neat division called marketing which is paid to inflate specs and lie.. on their 12000 series routers they count packets coming in AND leaving the router as throughput even tho you can only push so much into it :) - Original Message - From: "Chuck Larrieu" To: Sent: Thursday, June 07, 2001 1:01 AM Subject: RE: Layer3 switch vs Router [7:7406] > So layer three switches are faster, 'eh? By orders of magnitude, 'eh? This > calls for a bit of research on CCO. > > Hhhmmm > > Catalyst 8500 = 24 million PPS > http://www.cisco.com/univercd/cc/td/doc/pcat/ca8500c.htm#CJAEJHDF > > Catalyst 6509 = 170 million PPS > http://www.cisco.com/univercd/cc/td/doc/pcat/ca6000.htm > > Cisco 12000 = 375 million PPS > http://www.cisco.com/univercd/cc/td/doc/pcat/12000.htm > > Cisco 7600 - 30 million PPS > http://www.cisco.com/univercd/cc/td/doc/pcat/7600.htm > > > so it would appear, based on Cisco's own product literature, that high end > router versus high end switch, the edge most definitely goes to the product > Cisco calls a router. and numbers are all over the place, to judge from the > example I have looked at. > > Look, my point remains that any trickery, hardware or otherwise, can be > applied to "routers" as well as "switches". > > It most definitely is NOT enough to say that there is a difference and it is > because of the hardware construction of a "switch" versus that of a "router" > > Chuck > > -Original Message- > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] On Behalf Of > Michael L. Williams > Sent: Wednesday, June 06, 2001 8:52 PM > To: [EMAIL PROTECTED] > Subject: Re: Layer3 switch vs Router [7:7406] > > "Sergei Gearasimtchouk" wrote in message > [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > > I am sorry, should have said some thing meaningful. :( > > hypothetically speaking, if the ACLs are in place, wire speed is gone. > > The concept route one switch many is no longer holds its value. > > That's what I thought you meant. I'm glad you clarified your position. > > But it's incorrect. Multilayer switching (& therefore wire speed "routing") > are out the door only when you have an ACL applied to the MLS-RP interface > as an incoming ACL. That's it. This is where flow masks come into play. > There are 4 situations that need to be considered when using ACLs and > Multilayer switching: > > 1) Where there is an incoming ACL on the MLS-RP interface, Multilayer > switching is out the window because every incoming packet must be examined > by the router. > > 2) If there is no access list, you can use a Destination IP flow mask, the > simplest of the flow masks, where only the destination IP address is looked > for in the MLS cache. > > 3) When there is a outgoing standard IP ACL applied to the MLS-RP interface, > a Source-Destination IP flow mask needs to be used. This forces the MLS-SE > to look for an entry with both the source and destination IP addresses in > the MLS cache. Here's the reason why: > > If a packet has been sent from the MLS-SE to the MLS-RP, the packet gets > routed, then the outgoing ACL is applied. If the packet makes it back to > the MLS-SE, then the MLS-SE knows that the packet was allowed (not denied by > the ACL) and it makes a MLS cache entry. Since a standard IP ACL uses > source IP to permit/deny, the MLS-SE needs to look for the source IP as well > as the destination IP in the MLS cache. Any subsequent packets from/to the > same source/destination need not be compared to the ACL again as the > criteria for the ACL on the original packet was satisfied. > > 4) When there is an outgoing extended IP ACL applied to the MLS-RP > interface, an IP Flow mask needs to be used. An IP Flow masks instructs the > MLS-SE to look for an entry that contains the source IP and port AND > destination IP and port (basically Layers 3 AND 4). The MLS-SE must look > for all of that information in the MLS cache because extended IP ACLs > permit/deny using all of those criteria. Again, the same reasoning applies > as far as the ACL goes, which is: if the first packet sent to the MLS-RP > comes back to the MLS-SE, then the MLS-SE knows that the packet was allowed > (not denied) by the ACL, and therefore it doesn't need to check the ACL for > subsequent packet and Multilayer switching continues as normal. > > Most of the time an incoming ACL can be re-written as an outgoing ACL on > other interfaces. Although it is usually recommended to use incoming ACLs > over outgoing ACLs (so that traffic unwanted traffic doesn't get into the >
Re: Layer3 switch vs Router [7:7406]
I think on any of those units, to reach it's maximum throughput you have to enable and configure multilayer switching. If you look at the name on the Cisco 12000 you'll see it's called a GSR = Gigabit Switch-Router. At this point, even Cisco realizes that it's incorrect to call it simply a router because anymore the combinations of switches and routers have been combined. The real funny thing is, out of all of the units you listed, Cisco only calls one of them a (plain) router, the 7600. The others are refered to as either a switch-router or a multilayer switch. So, you'll notice the only router listed here can do 30 million PPS, while the two high end switches can do almost 6 times (170 mPPS) and then over 12 times (over an order of magnitude more) than the actual router... so thank you for proving my point. =) Having said all that, my whole point is multilayer switching integrates the best of routing and switching to provide better performance.. and I think my point has been proven. I wish I could log into CCO =( Mike W. "Chuck Larrieu" wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > So layer three switches are faster, 'eh? By orders of magnitude, 'eh? This > calls for a bit of research on CCO. > > Hhhmmm > > Catalyst 8500 = 24 million PPS > http://www.cisco.com/univercd/cc/td/doc/pcat/ca8500c.htm#CJAEJHDF > > Catalyst 6509 = 170 million PPS > http://www.cisco.com/univercd/cc/td/doc/pcat/ca6000.htm > > Cisco 12000 = 375 million PPS > http://www.cisco.com/univercd/cc/td/doc/pcat/12000.htm > > Cisco 7600 - 30 million PPS > http://www.cisco.com/univercd/cc/td/doc/pcat/7600.htm > > > so it would appear, based on Cisco's own product literature, that high end > router versus high end switch, the edge most definitely goes to the product > Cisco calls a router. and numbers are all over the place, to judge from the > example I have looked at. > > Look, my point remains that any trickery, hardware or otherwise, can be > applied to "routers" as well as "switches". > > It most definitely is NOT enough to say that there is a difference and it is > because of the hardware construction of a "switch" versus that of a "router" > > Chuck > > -Original Message----- > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] On Behalf Of > Michael L. Williams > Sent: Wednesday, June 06, 2001 8:52 PM > To: [EMAIL PROTECTED] > Subject: Re: Layer3 switch vs Router [7:7406] > > "Sergei Gearasimtchouk" wrote in message > [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > > I am sorry, should have said some thing meaningful. :( > > hypothetically speaking, if the ACLs are in place, wire speed is gone. > > The concept route one switch many is no longer holds its value. > > That's what I thought you meant. I'm glad you clarified your position. > > But it's incorrect. Multilayer switching (& therefore wire speed "routing") > are out the door only when you have an ACL applied to the MLS-RP interface > as an incoming ACL. That's it. This is where flow masks come into play. > There are 4 situations that need to be considered when using ACLs and > Multilayer switching: > > 1) Where there is an incoming ACL on the MLS-RP interface, Multilayer > switching is out the window because every incoming packet must be examined > by the router. > > 2) If there is no access list, you can use a Destination IP flow mask, the > simplest of the flow masks, where only the destination IP address is looked > for in the MLS cache. > > 3) When there is a outgoing standard IP ACL applied to the MLS-RP interface, > a Source-Destination IP flow mask needs to be used. This forces the MLS-SE > to look for an entry with both the source and destination IP addresses in > the MLS cache. Here's the reason why: > > If a packet has been sent from the MLS-SE to the MLS-RP, the packet gets > routed, then the outgoing ACL is applied. If the packet makes it back to > the MLS-SE, then the MLS-SE knows that the packet was allowed (not denied by > the ACL) and it makes a MLS cache entry. Since a standard IP ACL uses > source IP to permit/deny, the MLS-SE needs to look for the source IP as well > as the destination IP in the MLS cache. Any subsequent packets from/to the > same source/destination need not be compared to the ACL again as the > criteria for the ACL on the original packet was satisfied. > > 4) When there is an outgoing extended IP ACL applied to the MLS-RP > interface, an IP Flow mask needs to be used. An IP Flow masks instructs the > MLS-SE to look for an entry that contains the source IP and port AND > d
Re: Layer3 switch vs Router [7:7406]
Jason, the real answer to your questions is this. first why do we use layer 3 devices.. well MAINLY for intervlan routing,,,we are all agreed...yes then , we migh have these two different setup`s. a 6500 with an internal MSFC on a sup 2G... and a 6500 with an external router ...a 3620..with GBIC and 32 meg if ram(base spec) AGGREED the only real difference is.latency...and space YES i know the specs don`t equate BUT i am answering his question... in a perfect world both setup`s would be identical ...if that was the case then 1. you need more space having 2 seperate devices... 2. you will suffer from a slight speed differnce with the msfc sending info over the cat`s inbuilt backplane..3 gig and you sending info over the 1 gig link form switch to external router...this is ALL... forget packets/bytes/bits per secondthis is where your speed in/decreases are seen . SO if your asking this question because managment want to know WHY they should by a 6500 and msfc . i hope that answers your question. steve( i`ve been more char-grilled.(because of this responce) than a BK Flamer) >From: "Denton, Jason" >Reply-To: "Denton, Jason" >To: [EMAIL PROTECTED] >Subject: Layer3 switch vs Router [7:7406] >Date: Wed, 6 Jun 2001 15:35:16 -0400 > >Can anyone tell me what the REAL difference is between a layer3 switch and >a >router? > >Jason _ Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com. Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=7506&t=7406 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Layer3 switch vs Router [7:7406]
Chuck, Reflecting on my post, about the only thing that could be "proven" is that they seem to call most of their newer/higher end models switch-routers.. I don't know if looking at the PPS is a great indication just because technologies change and get better.. So I can't say that the higher PPS of the 12000 and 8500 are due to multilayer switching only I have alot of respect for you, so I don't want you to feel that I'm trying to contradict you to make you look bad or anything I don't even think it's possible for me to make you look bad =) The whole point of all of this stuff was tho that Multilayer switching is a great thing =) Mike W. "Michael L. Williams" wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > I think on any of those units, to reach it's maximum throughput you have to > enable and configure multilayer switching. > > If you look at the name on the Cisco 12000 you'll see it's called a GSR = > Gigabit Switch-Router. At this point, even Cisco realizes that it's > incorrect to call it simply a router because anymore the combinations of > switches and routers have been combined. > > The real funny thing is, out of all of the units you listed, Cisco only > calls one of them a (plain) router, the 7600. The others are refered to as > either a switch-router or a multilayer switch. So, you'll notice the only > router listed here can do 30 million PPS, while the two high end switches > can do almost 6 times (170 mPPS) and then over 12 times (over an order of > magnitude more) than the actual router... so thank you for proving my > point. =) > > Having said all that, my whole point is multilayer switching integrates the > best of routing and switching to provide better performance.. and I > think my point has been proven. > > I wish I could log into CCO =( > > Mike W. > > "Chuck Larrieu" wrote in message > [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > > So layer three switches are faster, 'eh? By orders of magnitude, 'eh? This > > calls for a bit of research on CCO. > > > > Hhhmmm > > > > Catalyst 8500 = 24 million PPS > > http://www.cisco.com/univercd/cc/td/doc/pcat/ca8500c.htm#CJAEJHDF > > > > Catalyst 6509 = 170 million PPS > > http://www.cisco.com/univercd/cc/td/doc/pcat/ca6000.htm > > > > Cisco 12000 = 375 million PPS > > http://www.cisco.com/univercd/cc/td/doc/pcat/12000.htm > > > > Cisco 7600 - 30 million PPS > > http://www.cisco.com/univercd/cc/td/doc/pcat/7600.htm > > > > > > so it would appear, based on Cisco's own product literature, that high end > > router versus high end switch, the edge most definitely goes to the > product > > Cisco calls a router. and numbers are all over the place, to judge from > the > > example I have looked at. > > > > Look, my point remains that any trickery, hardware or otherwise, can be > > applied to "routers" as well as "switches". > > > > It most definitely is NOT enough to say that there is a difference and it > is > > because of the hardware construction of a "switch" versus that of a > "router" > > > > Chuck > > > > -Original Message- > > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] On Behalf Of > > Michael L. Williams > > Sent: Wednesday, June 06, 2001 8:52 PM > > To: [EMAIL PROTECTED] > > Subject: Re: Layer3 switch vs Router [7:7406] > > > > "Sergei Gearasimtchouk" wrote in message > > [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > > > I am sorry, should have said some thing meaningful. :( > > > hypothetically speaking, if the ACLs are in place, wire speed is gone. > > > The concept route one switch many is no longer holds its value. > > > > That's what I thought you meant. I'm glad you clarified your position. > > > > But it's incorrect. Multilayer switching (& therefore wire speed > "routing") > > are out the door only when you have an ACL applied to the MLS-RP interface > > as an incoming ACL. That's it. This is where flow masks come into play. > > There are 4 situations that need to be considered when using ACLs and > > Multilayer switching: > > > > 1) Where there is an incoming ACL on the MLS-RP interface, Multilayer > > switching is out the window because every incoming packet must be examined > > by the router. > > > > 2) If there is no access list, you can use a Destination IP flow mask, the > > simplest
RE: Layer3 switch vs Router [7:7406]
My point entirely. In the old world, a device that concerned itself with the IP address was a router, and a device that dealt with the MAC address ( yes I know this is not exactly true, in that routers do have to deal with MAC's.) A router's job is path determination and packet forwarding based on that determination. In the old world, a switch is really a multiport bridge. In the new world, speed is the driving factor, and the designers use every trick they can to increase speed. These innovations are not limited to layer two or layer three. In fact, it is good to recall that in reality there is no such thing as layer two or layer three. Devices operate on a bitstream, use offsets to determine where the information is that they need to proceed, use buffers and caches and specialized architecture to accomplish what they need to accomplish, and faster than ever. I'm willing to bet, though, that when you got into the discussion at the EE level ( something I am totally not qualified to do ) that you would find where the real distinction are, if there are any. I know I am not the only one who has attempted to wade through the white papers and walk away thinking I've just bought a bridge ( so to speak ) Chuck -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] On Behalf Of Michael L. Williams Sent: Thursday, June 07, 2001 4:54 AM To: [EMAIL PROTECTED] Subject: Re: Layer3 switch vs Router [7:7406] I think on any of those units, to reach it's maximum throughput you have to enable and configure multilayer switching. If you look at the name on the Cisco 12000 you'll see it's called a GSR = Gigabit Switch-Router. At this point, even Cisco realizes that it's incorrect to call it simply a router because anymore the combinations of switches and routers have been combined. The real funny thing is, out of all of the units you listed, Cisco only calls one of them a (plain) router, the 7600. The others are refered to as either a switch-router or a multilayer switch. So, you'll notice the only router listed here can do 30 million PPS, while the two high end switches can do almost 6 times (170 mPPS) and then over 12 times (over an order of magnitude more) than the actual router... so thank you for proving my point. =) Having said all that, my whole point is multilayer switching integrates the best of routing and switching to provide better performance.. and I think my point has been proven. I wish I could log into CCO =( Mike W. "Chuck Larrieu" wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > So layer three switches are faster, 'eh? By orders of magnitude, 'eh? This > calls for a bit of research on CCO. > > Hhhmmm > > Catalyst 8500 = 24 million PPS > http://www.cisco.com/univercd/cc/td/doc/pcat/ca8500c.htm#CJAEJHDF > > Catalyst 6509 = 170 million PPS > http://www.cisco.com/univercd/cc/td/doc/pcat/ca6000.htm > > Cisco 12000 = 375 million PPS > http://www.cisco.com/univercd/cc/td/doc/pcat/12000.htm > > Cisco 7600 - 30 million PPS > http://www.cisco.com/univercd/cc/td/doc/pcat/7600.htm > > > so it would appear, based on Cisco's own product literature, that high end > router versus high end switch, the edge most definitely goes to the product > Cisco calls a router. and numbers are all over the place, to judge from the > example I have looked at. > > Look, my point remains that any trickery, hardware or otherwise, can be > applied to "routers" as well as "switches". > > It most definitely is NOT enough to say that there is a difference and it is > because of the hardware construction of a "switch" versus that of a "router" > > Chuck > > -Original Message- > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] On Behalf Of > Michael L. Williams > Sent: Wednesday, June 06, 2001 8:52 PM > To: [EMAIL PROTECTED] > Subject: Re: Layer3 switch vs Router [7:7406] > > "Sergei Gearasimtchouk" wrote in message > [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > > I am sorry, should have said some thing meaningful. :( > > hypothetically speaking, if the ACLs are in place, wire speed is gone. > > The concept route one switch many is no longer holds its value. > > That's what I thought you meant. I'm glad you clarified your position. > > But it's incorrect. Multilayer switching (& therefore wire speed "routing") > are out the door only when you have an ACL applied to the MLS-RP interface > as an incoming ACL. That's it. This is where flow masks come into play. > There are 4 situations that need to be considered when using ACLs and > Multilayer switching: > > 1) Where there is an incoming ACL on t
Re: Layer3 switch vs Router [7:7406]
I am testing MLS on a cat5500 and have not been able to demonstrate any throughput improvement using FTP as a test application. The cat5500 has SupIII (4.5.12), RSM (12.0.7T) with NFFCII and 3 24port 10/100 ethernet line cards. I have 7 Vlans configured and the mls settings on both the RSM and SupIII. When FTP is run inter VLAN the throughput is same whether I have MLS enabled or not on the SupIII card. When MLS is enabled I have verified functionality using the various show mls commands so I am sure its working I just don't see any throughput improvement. Is this a function of ftp client and server performance (using laptops with 10/100 ethernet cards on NT)? Should I use a different application or unix client / server to test throughput? If someone has any information I would appreciate your experience. ""Denton, Jason"" wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > Can anyone tell me what the REAL difference is between a layer3 switch and a > router? > > Jason Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=7603&t=7406 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Layer3 switch vs Router [7:7406]
I just wanted to get my $0.02 in, but the message had gotten so long I think the filters dropped my response. I apologize if this is a duplicate. Priscilla At 12:39 AM 6/7/01, Michael L. Williams wrote: >Chuck.. I talked to a good friend of mine that knows more of this than >I do.. and even HE wasn't clear on the line of switch -vs- router. >so my following comments are strickly my thinking out loud.. mostly to >get feedback . > >I don't think there is a difference in a layer 3 switch that does 100,000 >packets/sec -vs- a router that does 100,000 packets/sec. However, >respectfully submit that I don't know of any routers that can keep up with >Layer 3 switches because in multilayer switching the route processor only >has to route the first packet in a flow. Yes, but. Isn't that true for a router with fast switching, silicon switching, optimum switching, distributed switching, etc? And with NetFlow switching, a router can take into account access control lists and QoS features that need to be applied to a flow, much in the same way that these new MLS switches can do this with their flow masks. (Thanks for your earlier message that explained flow masks so well.) I agree that MLS has great potential. It sounds complicated to configure and hard to troubleshoot, though. I think I would keep a hub and a protocol analyzer handy when first implementing it, so I could check traffic between the MLS-RP and MLS-SE when things went wrong. Regarding packets-per-second, we need to remember that this is a marketing game. The enormous numbers come from the absolute maximum possible number of packets on a Gigabit Ethernet, taking into account the inter-frame gap and preamble. The test engineers pump frames of the smallest possible size into the switch to make the numbers really look big. (I wonder if they take into account the carrier extension with Gigabit Ethernet? That would make the numbers less.) The PPS is based on this max number of packets coming in one port and going out another Gigabit Ethernet port. They can increase the numbers even more by using multiple ingress and egress ports and no contention for an egress port. The numbers for both switches and some routers are so astronomically high these days that they stretch credibility. Do real-world traffic generators really send that much traffic? Regarding CPUs, the general-purpose CPU on the Cisco routers may not be very fast, but the high-end routers also have Versatile Interface Processors that help with high-speed switching. One last point is that routers have features that switches don't have today. We configure access lists on routers. (Although an MLS-SE can make use of these access control lists, we still configure them on the router). Routers run running protocols. Routers act as firewalls, policy servers, handle RSVP and other QoS requests, connect telephones, act as DHCP servers, connect modems both analog and cable, etc. Just a few thoughts before this interesting discussion undergoes a well-deserved retirement. Priscilla Priscilla Oppenheimer http://www.priscilla.com Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=7608&t=7406 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Layer3 switch vs Router [7:7406]
How 'bout $.03? If you look at the newest Cisco announcements, its clear that the GSR and 6500 technology will replace the legacy 75xx and other high-end router platforms. These systems, depending on firmware, will use hardware based CEF, which will negate the MLS flow establishment process. In addition, with the FlexWAN technology, Cisco is trying to steer a course that places the 6500 and 7600 (a 6500 on its side) in distribution and core layer WAN, with the GSR serving IP backbone/transit. = Robert Padjen __ Do You Yahoo!? Get personalized email addresses from Yahoo! Mail - only $35 a year! http://personal.mail.yahoo.com/ Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=7617&t=7406 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Layer3 switch vs Router [7:7406]
Unfortunately, you'd be hard pressed to even stress the router CPU with a single FTP going from a 10/100 NIC... Even 100Mbps won't push it With that "low" throughput, you really wouldn't see a difference in speed... Question: Are the 2 machines that the file is being transferred between on difference subnets? This would need to be true to test the router-vs-multilayer switch speeds anyway.. "Luke" wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > I am testing MLS on a cat5500 and have not been able to demonstrate any > throughput improvement using FTP as a test application. The cat5500 has > SupIII (4.5.12), RSM (12.0.7T) with NFFCII and 3 24port 10/100 ethernet line > cards. I have 7 Vlans configured and the mls settings on both the RSM and > SupIII. When FTP is run inter VLAN the throughput is same whether I have > MLS enabled or not on the SupIII card. When MLS is enabled I have verified > functionality using the various show mls commands so I am sure its working I > just don't see any throughput improvement. Is this a function of ftp client > and server performance (using laptops with 10/100 ethernet cards on NT)? > Should I use a different application or unix client / server to test > throughput? > > If someone has any information I would appreciate your experience. > > > > > > ""Denton, Jason"" wrote in message > [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > > Can anyone tell me what the REAL difference is between a layer3 switch and > a > > router? > > > > Jason Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=7650&t=7406 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Layer3 switch vs Router [7:7406]
Robert/Priscilla, That's a very good point about the CEF.. I knew that CEF was the "ultimate" as far as switching, etc. I'd like to learn much more about it's details Mike W. "Robert Padjen" wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > How 'bout $.03? > > If you look at the newest Cisco announcements, its > clear that the GSR and 6500 technology will replace > the legacy 75xx and other high-end router platforms. > These systems, depending on firmware, will use > hardware based CEF, which will negate the MLS flow > establishment process. In addition, with the FlexWAN > technology, Cisco is trying to steer a course that > places the 6500 and 7600 (a 6500 on its side) in > distribution and core layer WAN, with the GSR serving > IP backbone/transit. > > = > Robert Padjen > > __ > Do You Yahoo!? > Get personalized email addresses from Yahoo! Mail - only $35 > a year! http://personal.mail.yahoo.com/ Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=7643&t=7406 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Layer3 switch vs Router [7:7406]
switch vs. router question Response - it depends on what you want it to do. If you want something that makes no routing decisions - then a switch is the answer. Switches have basically one job at either level. On the other hand you have warts :) Really - routers will have a different load to handle, even in a multi layered approach. So, a router is likely to be slower in accomplishing mega packets per second. Make the decision based on what it will be used for in the network design. Remember use the right tool for the job and no one gets hurt. Darel R Graham Beer is proof that God loves us and wants us to be happy. -Benjamin Franklin -Original Message- From: Priscilla Oppenheimer [mailto:[EMAIL PROTECTED]] Sent: Thursday, June 07, 2001 3:52 PM To: [EMAIL PROTECTED] Subject: Re: Layer3 switch vs Router [7:7406] I just wanted to get my $0.02 in, but the message had gotten so long I think the filters dropped my response. I apologize if this is a duplicate. Priscilla At 12:39 AM 6/7/01, Michael L. Williams wrote: >Chuck.. I talked to a good friend of mine that knows more of this than >I do.. and even HE wasn't clear on the line of switch -vs- router. >so my following comments are strickly my thinking out loud.. mostly to >get feedback . > >I don't think there is a difference in a layer 3 switch that does 100,000 >packets/sec -vs- a router that does 100,000 packets/sec. However, >respectfully submit that I don't know of any routers that can keep up with >Layer 3 switches because in multilayer switching the route processor only >has to route the first packet in a flow. Yes, but. Isn't that true for a router with fast switching, silicon switching, optimum switching, distributed switching, etc? And with NetFlow switching, a router can take into account access control lists and QoS features that need to be applied to a flow, much in the same way that these new MLS switches can do this with their flow masks. (Thanks for your earlier message that explained flow masks so well.) I agree that MLS has great potential. It sounds complicated to configure and hard to troubleshoot, though. I think I would keep a hub and a protocol analyzer handy when first implementing it, so I could check traffic between the MLS-RP and MLS-SE when things went wrong. Regarding packets-per-second, we need to remember that this is a marketing game. The enormous numbers come from the absolute maximum possible number of packets on a Gigabit Ethernet, taking into account the inter-frame gap and preamble. The test engineers pump frames of the smallest possible size into the switch to make the numbers really look big. (I wonder if they take into account the carrier extension with Gigabit Ethernet? That would make the numbers less.) The PPS is based on this max number of packets coming in one port and going out another Gigabit Ethernet port. They can increase the numbers even more by using multiple ingress and egress ports and no contention for an egress port. The numbers for both switches and some routers are so astronomically high these days that they stretch credibility. Do real-world traffic generators really send that much traffic? Regarding CPUs, the general-purpose CPU on the Cisco routers may not be very fast, but the high-end routers also have Versatile Interface Processors that help with high-speed switching. One last point is that routers have features that switches don't have today. We configure access lists on routers. (Although an MLS-SE can make use of these access control lists, we still configure them on the router). Routers run running protocols. Routers act as firewalls, policy servers, handle RSVP and other QoS requests, connect telephones, act as DHCP servers, connect modems both analog and cable, etc. Just a few thoughts before this interesting discussion undergoes a well-deserved retirement. Priscilla Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=7632&t=7406 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Layer3 switch vs Router [7:7406]
At 04:55 PM 6/7/01, Graham, Darel R. wrote: >switch vs. router question > > Response - it depends on what you want it to do. > If you want something that makes no routing decisions - then a >switch is the answer. A switch makes a forwarding decision. A router that has cached the MAC-layer encapsulation for outgoing frames for a destination (and possibly source and port number) also makes a decision, and it can make that decision essentially as fast as a switch can make its decision. A router runs routing protocols. In an optimized architecture, running routing protocols does not affect the performance of forwarding packets. A switch runs Spanning Tree Algorithm and possibly VTP and other management (control?) protocols. In an optimized architecture, running these protocols does not affect the performance of forwarding packets. > Switches have basically one job at either level. > > On the other hand you have warts :) Thanks a lot!? ;-) > Really - routers will have a different load to handle, even in a >multi layered approach. > So, a router is likely to be slower in accomplishing mega packets >per second. You think this is slow? Cisco 12000 = 375 million PPS http://www.cisco.com/univercd/cc/td/doc/pcat/12000.htm Cisco 7600 - 30 million PPS http://www.cisco.com/univercd/cc/td/doc/pcat/7600.htm My conclusion: They're the same damn thing! Does anyone remember that Janis Joplin song where she sings about travelling by train with her group when they discovered that night and day are the same f***ing thing! ;-) Priscilla > Make the decision based on what it will be used for in the network >design. > Remember use the right tool for the job and no one gets hurt. > >Darel R Graham >Beer is proof that God loves us and wants us to be happy. >-Benjamin Franklin > > > >-Original Message- >From: Priscilla Oppenheimer [mailto:[EMAIL PROTECTED]] >Sent: Thursday, June 07, 2001 3:52 PM >To: [EMAIL PROTECTED] >Subject: Re: Layer3 switch vs Router [7:7406] > > >I just wanted to get my $0.02 in, but the message had gotten so long I >think the filters dropped my response. I apologize if this is a duplicate. > >Priscilla > >At 12:39 AM 6/7/01, Michael L. Williams wrote: > >Chuck.. I talked to a good friend of mine that knows more of this than > >I do.. and even HE wasn't clear on the line of switch -vs- router. > >so my following comments are strickly my thinking out loud.. mostly to > >get feedback . > > > >I don't think there is a difference in a layer 3 switch that does 100,000 > >packets/sec -vs- a router that does 100,000 packets/sec. However, > >respectfully submit that I don't know of any routers that can keep up with > >Layer 3 switches because in multilayer switching the route processor only > >has to route the first packet in a flow. > >Yes, but. Isn't that true for a router with fast switching, silicon >switching, optimum switching, distributed switching, etc? And with NetFlow >switching, a router can take into account access control lists and QoS >features that need to be applied to a flow, much in the same way that these >new MLS switches can do this with their flow masks. (Thanks for your >earlier message that explained flow masks so well.) > >I agree that MLS has great potential. It sounds complicated to configure >and hard to troubleshoot, though. I think I would keep a hub and a protocol >analyzer handy when first implementing it, so I could check traffic between >the MLS-RP and MLS-SE when things went wrong. > >Regarding packets-per-second, we need to remember that this is a marketing >game. The enormous numbers come from the absolute maximum possible number >of packets on a Gigabit Ethernet, taking into account the inter-frame gap >and preamble. The test engineers pump frames of the smallest possible size >into the switch to make the numbers really look big. (I wonder if they take >into account the carrier extension with Gigabit Ethernet? That would make >the numbers less.) The PPS is based on this max number of packets coming in >one port and going out another Gigabit Ethernet port. They can increase the >numbers even more by using multiple ingress and egress ports and no >contention for an egress port. > >The numbers for both switches and some routers are so astronomically high >these days that they stretch credibility. Do real-world traffic generators >really send that much traffic? > >Regarding CPUs, the general-purpose CPU on the Cisco routers may not be >very fast, but the high-end routers also have Versatile Interface >Processors that help with high-speed switchin
Re: Layer3 switch vs Router [7:7406]
che) in a single "cycle". I know know if that's the correct terminology, >but my point being that an ASIC is able to do this type of thing. A general >purpose CPU running IOS code, etc would take many clock cycles to perform >the same type operations and it's speed can't compare to an ASIC. > >I have to say though, that I'm not all that familiar with the top end >routers (switch-routers, whatever) like the 12000 GSRs (or the new 10Gig >SRs), etc. so perhaps they have some ASICs to perform their >routing.. dunno. > >My 2 cents.. > >Mike W. > >"Chuck Larrieu" wrote in message >[EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > > Very good, and thanks. > > > > But... to quote a sage, who made this point last time this topic came up, > > what exactly is the difference between a router that routes 100,000 >packets > > per second, and a layer three switch that switches 100,000 packets per > > second? > > > > Cisco can talk about ASIC's versus processors all they want. Both are >chips. > > High end routers also have ASIC's as well as other means to optimize >traffic > > flow. > > > > Truth be told, layer 3 switch is a marketing concept, plain and simple. > > > > Chuck > > > > -Original Message- > > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] On Behalf Of > > Michael L. Williams > > Sent: Wednesday, June 06, 2001 3:56 PM > > To: [EMAIL PROTECTED] > > Subject: Re: Layer3 switch vs Router [7:7406] > > > > For the record: Layer 3 switch = Multilayer switch (I say this because I > > like to use the term Multilayer switch rather than Layer 3 switch... dunno > > why... I guess because in the switch/routers, you actually use and >configure > > Multilayer switching) > > > > In reply to some of the other posts on this topic: > > > > >This is actually covered in under the switching portion of the CCNP.. > > >Here is a link from Cisco for you to reference: > > >http://www.cisco.com/warp/public/cc/so/neso/lnso/cpso/l3c85_wp.htm > > > > Layer 3 switching (Multilayer switching) *is* covered on the CCNP >Switching > > exam and I don't know how one could pass it without an understanding of >how > > it works. (although that link that was provided pointed to a page that > > didn't explain MLS very well at all) > > > > > One differance is that a layer 3 switch does wire-speed switching > > > > AFAIK, *all* switches perform wire-speed switching, as long as the >backplane > > isn't oversubscribed (even then what gets switched is done at wirespeed >and > > other stuff is dropped). Can someone make sure I'm not fibbing or >confused > > on this? > > > > >Okay, two things - > > > > > >One - abduct a Cisco marketing rep, tie them to a chair, shine a bright, > > hot > > >light in their face and ask *them* what the difference is. > > > > > >Two - while they're tied up, ask them what "wire-speed" is supposed to > > mean. > > > > Wire-speed simply means that the data is switched across the backplane to > > the destination port ASAP, as fast as the wires can carry the data thru >the > > ASICs and to the destination port. I.E. the speed of light (minus a small > > fraction because the wires do actually have a non-zero resistance =) > > > > >Someone may have a product based answer for you but literally a router is >a > > >layer 3 switch. Just think of all of the functionality that a switch > > offers > > >you and add on the route switch module to sweeten the pot. > > >A router either bridges or has separate subnets on each of its > > >interfaces.(simplistic answer of course). > > > > This is very misleading. Although a router has a switching process within > > it, and that switching process can take on many forms, a router is NOT > > simply a Layer 3 switch. Although a router can bridge (including bridging > > VLANS using Integrated Routing and Bridging), even then it is not the > > equivalent to a switch because of the way it performs the process (in > > software on a CPU instead of with an ASIC). The router doesn't keep a CAM > > table like a switch, etc. and without something like a NetFlow Feature >Card > > or MLS processor, a router can't bridge (switch) at wirespeed like a true > > Layer 2 switch.. Even on a switch/router with a NFFC or the like, > > without Multilayer switching enabled, it's like a router with a ton
Re: Layer3 switch vs Router [7:7406]
Mike, Thanks for the response. I have tried both inside and outside the same subnet (intra vs inter VLAN) on the one switch. Did not see any difference that is why I assume I am not stressing the equipment sufficiently to see the difference. Can you recommend a scenerio that would stress the configuration that does require anything more than a handfull of laptops (i.e. some software product), or should I setup some X number of FTP stations to one server and retest? Again, thanks, I have been able to see the benefit of channeling and trunking and . but have been unsuccessful with the MLS. Priscilla, I found that the configuration of MLS was somewhat cumbersome (not necessarily difficult) when using an RSM. I just followed the steps laid out in the CCIE Lan Switching book (dare I say bible) by Clark&Hamilton page 483 , the switch side MLS is enabled by default and no other config is necessary if your using an RSM in the switch. Although I did test the various settings (dest, dest-sourc and so on). Regards, ""Michael L. Williams"" wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > Unfortunately, you'd be hard pressed to even stress the router CPU with a > single FTP going from a 10/100 NIC... Even 100Mbps won't push it > With that "low" throughput, you really wouldn't see a difference in > speed... Question: Are the 2 machines that the file is being > transferred between on difference subnets? This would need to be true to > test the router-vs-multilayer switch speeds anyway.. > > "Luke" wrote in message > [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > > I am testing MLS on a cat5500 and have not been able to demonstrate any > > throughput improvement using FTP as a test application. The cat5500 has > > SupIII (4.5.12), RSM (12.0.7T) with NFFCII and 3 24port 10/100 ethernet > line > > cards. I have 7 Vlans configured and the mls settings on both the RSM and > > SupIII. When FTP is run inter VLAN the throughput is same whether I have > > MLS enabled or not on the SupIII card. When MLS is enabled I have > verified > > functionality using the various show mls commands so I am sure its working > I > > just don't see any throughput improvement. Is this a function of ftp > client > > and server performance (using laptops with 10/100 ethernet cards on NT)? > > Should I use a different application or unix client / server to test > > throughput? > > > > If someone has any information I would appreciate your experience. > > > > > > > > > > > > ""Denton, Jason"" wrote in message > > [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > > > Can anyone tell me what the REAL difference is between a layer3 switch > and > > a > > > router? > > > > > > Jason Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=7727&t=7406 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
