Re: L3 Switching & Swtich/Router Comparsion [7:62273]
Howard C. Berkowitz wrote: > > At 7:29 PM + 1/31/03, Chuck Church wrote: > >I got into this discussion kind of late, but here's my take: > > > >Functionally, you can configure either to do what you want. > But a 1 armed > >router has a couple major limitations that a layer 3 switch > doesn't. A > >layer 3 switch has ASICs (application specific integrated > chip/circuit) that > >can perform MAC re-writes, RIB/FIB lookups, rate-limiting, > QOS, and ACL at > >wire speed without bothering the CPU of the device. > > As you point out, a little indirectly with the footnote about > the VIP > in the table below, so do the 7500 and up. Even the 7000 can > have > separate routing and switching processors. > > Above the 7500, there's extensive use of ASICs and distributed > forwarding processors. > > MAC rewrites are normal functions in commercial L2 chips, so > that is an issue. > > The question really comes in the more sophisticated QoS and > routing > functions, which, after all, tend to be more needed in the WAN. > > > A 1 armed router needs > >to use the CPU for some of these functions, and will quickly > become a > >bottleneck after a certain level of traffic is passing through. > > Agreed, if it is a single CPU router. ASICs even appear on > some > lower-end devices for things like encryption. I think the real-world comparison that the original poster probably had in mind was a rather low-end, inexpensive one-armed router compared to a L3 switch. It sounds like we all agree that in general the L3 switch is going to have better performance in that case. > > >Also, a 1 > >armed router is limited by it's 1 arm :) That link will be > limited to 100 > >mb/sec (unless you move up to a 72xx or higher router, where > gig is > >possible). > > True. That is a good point. Another option, by the way, is a 2-armed router. Seriously, instead of doing inter-VLAN routing on one interface on the router, why not just add an Ethernet interface to the router? Duh. :-) This would be a solution somewhere in the middle with regards to cost and performance. Well, it's been a great discussion! Thanks everyone. Priscilla > > > So for instance if you're copying a large file between VLANs, > >it'd be pretty easy to use up all the bandwidth of that 100 > mbit full duplex > >link, even if the CPU wasn't working hard on the 1 armed > router. > > Looking at the broader picture, it isn't necessarily > route-versus-switch. A heavily used server can have multiple > NICs in > multiple VLANs, with full speed on each (including GE). A L2 > switch > can handle intra-VLAN switching. > > > Moving to > >a layer 3 switch typically bumps that layer 3 device to layer > 2 backplane a > >multi-gigabit speed connection. So if your traffic between > vlans will ever > >exceed 100 mbit, you can either shell out huge bucks for a > 72xx, or get a > >real QOS-friendly 3550 that is both faster and cheaper. Of > course if you > >need WAN modules in the device that's another story. I was > sent this chart > >a while ago listing speeds of various routers and switches: > > > >> Router Performance Specs > >> > >> Router Switching Performance - Performance based on 64 Byte > packets > > Obviously, there's a tremendous difference based on which > switching > path is used. It can be very feature-, release-, and > platform-dependent if enabling a given feature drops you out of > CEF, > fast switching, etc. > > It's been my experience this is more likely to happen in an > L3 > switch or low-end router. This isn't necessarily bad design. > Many > of these features are more critical in WANs than LANs, and > switches > are, reasonably enough, optimized for LANs. > > > > > >> PlatformProcess Fast Fast > >> SwitchingSwitching Switching > >> (PPS) (Mb/S) > > I suspect >>> is bps > > > > --- > >> 1400 6004,000 2,048,000 > >> 16006004,000 2,048,000 > >> 1700 1,5008,400 4,300,800 > >> 25008004,400 2,252,800 > >> 261X 1,500 15,000 7,680,000 > >> 262X 1,500 25,000 12,800,000 > >> 265X 2,000 37,000 18,944,000 > >> 3620 2,000 40,000 20,480,000 > >> 3640 4,000 80,000 40,960,000 > >> 3660 12,000 120,000 61,440,000 > >> MC38102,000 10,000 5,120,000 > >> 4000 1,800 14,000 7,168,000 > >> 4500 5,000 40,000 20,480,000 > >> 4700 7,000 50,000 25,600,000 > >> 7120 13,000 175,000 89,600,000 > > > 7140 20,000
Re: L3 Switching & Swtich/Router Comparsion [7:62273]
At 7:29 PM + 1/31/03, Chuck Church wrote: >I got into this discussion kind of late, but here's my take: > >Functionally, you can configure either to do what you want. But a 1 armed >router has a couple major limitations that a layer 3 switch doesn't. A >layer 3 switch has ASICs (application specific integrated chip/circuit) that >can perform MAC re-writes, RIB/FIB lookups, rate-limiting, QOS, and ACL at >wire speed without bothering the CPU of the device. As you point out, a little indirectly with the footnote about the VIP in the table below, so do the 7500 and up. Even the 7000 can have separate routing and switching processors. Above the 7500, there's extensive use of ASICs and distributed forwarding processors. MAC rewrites are normal functions in commercial L2 chips, so that is an issue. The question really comes in the more sophisticated QoS and routing functions, which, after all, tend to be more needed in the WAN. > A 1 armed router needs >to use the CPU for some of these functions, and will quickly become a >bottleneck after a certain level of traffic is passing through. Agreed, if it is a single CPU router. ASICs even appear on some lower-end devices for things like encryption. >Also, a 1 >armed router is limited by it's 1 arm :) That link will be limited to 100 >mb/sec (unless you move up to a 72xx or higher router, where gig is >possible). True. > So for instance if you're copying a large file between VLANs, >it'd be pretty easy to use up all the bandwidth of that 100 mbit full duplex >link, even if the CPU wasn't working hard on the 1 armed router. Looking at the broader picture, it isn't necessarily route-versus-switch. A heavily used server can have multiple NICs in multiple VLANs, with full speed on each (including GE). A L2 switch can handle intra-VLAN switching. > Moving to >a layer 3 switch typically bumps that layer 3 device to layer 2 backplane a >multi-gigabit speed connection. So if your traffic between vlans will ever >exceed 100 mbit, you can either shell out huge bucks for a 72xx, or get a >real QOS-friendly 3550 that is both faster and cheaper. Of course if you >need WAN modules in the device that's another story. I was sent this chart >a while ago listing speeds of various routers and switches: > >> Router Performance Specs >> >> Router Switching Performance - Performance based on 64 Byte packets Obviously, there's a tremendous difference based on which switching path is used. It can be very feature-, release-, and platform-dependent if enabling a given feature drops you out of CEF, fast switching, etc. It's been my experience this is more likely to happen in an L3 switch or low-end router. This isn't necessarily bad design. Many of these features are more critical in WANs than LANs, and switches are, reasonably enough, optimized for LANs. > > >> PlatformProcess Fast Fast >> SwitchingSwitching Switching >> (PPS) (Mb/S) I suspect >>> is bps > > --- >> 1400 6004,000 2,048,000 >> 16006004,000 2,048,000 >> 1700 1,5008,400 4,300,800 >> 25008004,400 2,252,800 >> 261X 1,500 15,000 7,680,000 >> 262X 1,500 25,000 12,800,000 >> 265X 2,000 37,000 18,944,000 >> 3620 2,000 40,000 20,480,000 >> 3640 4,000 80,000 40,960,000 >> 3660 12,000 120,000 61,440,000 >> MC38102,000 10,000 5,120,000 >> 4000 1,800 14,000 7,168,000 >> 4500 5,000 40,000 20,480,000 >> 4700 7,000 50,000 25,600,000 >> 7120 13,000 175,000 89,600,000 > > 7140 20,000 300,000153,600,000 >> 7200-NPE100 7,000 100,000 51,200,000 >> 7200-NPE150 10,000 150,000 76,800,000 >> 7200-NPE175 9,000 175,000 89,600,000 >> 7200-NPE200 13,000 200,000102,400,000 >> 7200-NPE225 13,000 225,000115,200,000 >> 7200-NPE300 20,000 300,000153,600,000 >> 7200-NPE400 20,000 400,000204,800,000 >> 7200-NSE-1 20,000 300,000153,600,000 >> uBR-NPE150 10,000 100,000 51,200,000 >> uBR-NPE200 13,000 150,000 76,800,000 >> 7000-RP 2,500 30,000 15,360,000 >> 7500-RSP2 5,000 220,000112,640,000 >> 7500-RSP4 8,000 345,000176,640,000 >> 7500-RSP822,000 470,000240,640,000 >> Cat 2948G-L3
Re: L3 Switching & Swtich/Router Comparsion [7:62273]
Chuck Church wrote: > > I got into this discussion kind of late, but here's my take: > > Functionally, you can configure either to do what you want. > But a 1 armed > router has a couple major limitations that a layer 3 switch > doesn't. A > layer 3 switch has ASICs (application specific integrated > chip/circuit) that > can perform MAC re-writes, RIB/FIB lookups, rate-limiting, QOS, > and ACL at > wire speed without bothering the CPU of the device. Chuck, Aren't there examples of switches with a one aremed router that can do MAC re-writes via MLS? I think all Cisco L3 switches have this capability and it is enabled by default. But I was under the impression that it could be done on a stick as well as in an integrated fashion. I think we've got a Cat 5500 in one of the labs. Maybe I should just try it out. Thanks for the list by the way. Regards, Scott > A 1 armed > router needs > to use the CPU for some of these functions, and will quickly > become a > bottleneck after a certain level of traffic is passing > through. Also, a 1 > armed router is limited by it's 1 arm :) That link will be > limited to 100 > mb/sec (unless you move up to a 72xx or higher router, where > gig is > possible). So for instance if you're copying a large file > between VLANs, > it'd be pretty easy to use up all the bandwidth of that 100 > mbit full duplex > link, even if the CPU wasn't working hard on the 1 armed > router. Moving to > a layer 3 switch typically bumps that layer 3 device to layer 2 > backplane a > multi-gigabit speed connection. So if your traffic between > vlans will ever > exceed 100 mbit, you can either shell out huge bucks for a > 72xx, or get a > real QOS-friendly 3550 that is both faster and cheaper. Of > course if you > need WAN modules in the device that's another story. I was > sent this chart > a while ago listing speeds of various routers and switches: > > > Router Performance Specs > > > > Router Switching Performance - Performance based on 64 Byte > packets > > > > PlatformProcess Fast Fast > >SwitchingSwitching Switching > > (PPS) (Mb/S) > > --- > > 1400 6004,000 2,048,000 > > 16006004,000 2,048,000 > > 1700 1,5008,400 4,300,800 > > 25008004,400 2,252,800 > > 261X 1,500 15,000 7,680,000 > > 262X 1,500 25,000 12,800,000 > > 265X 2,000 37,000 18,944,000 > > 3620 2,000 40,000 20,480,000 > > 3640 4,000 80,000 40,960,000 > > 3660 12,000 120,000 61,440,000 > > MC38102,000 10,000 5,120,000 > > 4000 1,800 14,000 7,168,000 > > 4500 5,000 40,000 20,480,000 > > 4700 7,000 50,000 25,600,000 > > 7120 13,000 175,000 89,600,000 > > 7140 20,000 300,000153,600,000 > > 7200-NPE100 7,000 100,000 51,200,000 > > 7200-NPE150 10,000 150,000 76,800,000 > > 7200-NPE175 9,000 175,000 89,600,000 > > 7200-NPE200 13,000 200,000102,400,000 > > 7200-NPE225 13,000 225,000115,200,000 > > 7200-NPE300 20,000 300,000153,600,000 > > 7200-NPE400 20,000 400,000204,800,000 > > 7200-NSE-1 20,000 300,000153,600,000 > > uBR-NPE150 10,000 100,000 51,200,000 > > uBR-NPE200 13,000 150,000 76,800,000 > > 7000-RP 2,500 30,000 15,360,000 > > 7500-RSP2 5,000 220,000112,640,000 > > 7500-RSP4 8,000 345,000176,640,000 > > 7500-RSP822,000 470,000240,640,000 > > Cat 2948G-L3N/A 10,000,000 5,120,000,000 > > Cat 4908G-L3N/A 12,000,000 6,144,000,000 > > Cat 4232-L3 N/A6,000,000 3,072,000,000 > > Cat -RSM 14,000 175,000 89,600,000 > > Catalyst-RSFC170,000 87,040,000 > > Catalyst-RSFC/NFFCII 2,000,000 1,024,000,000 > > Catalyst-MSFC (IP,IPX)15,000,000 7,680,000,000 > > Catalyst-MSFC (Other)170,000 87,040,000 > > Catalyst-MSFC2 (IP,IPX) 15,000,000 7,680,000,000 > > Catalyst-MSFC2 (Other) 680,000348,160,000 > > Catalyst-MSFC (X-bar) 30,000,000 15,360,000,000 > > > > NOTE: VIP2 Distributed Switching significantly increases > > the performance on RSP platforms. > > > Chuck Church > CCIE #8776, MCNE, MCSE > > > > Please advice if there are any difference in the > >>> > >>>functionalities etc. if I > >>> > use > > >
Re: L3 Switching & Swtich/Router Comparsion [7:62273]
I got into this discussion kind of late, but here's my take: Functionally, you can configure either to do what you want. But a 1 armed router has a couple major limitations that a layer 3 switch doesn't. A layer 3 switch has ASICs (application specific integrated chip/circuit) that can perform MAC re-writes, RIB/FIB lookups, rate-limiting, QOS, and ACL at wire speed without bothering the CPU of the device. A 1 armed router needs to use the CPU for some of these functions, and will quickly become a bottleneck after a certain level of traffic is passing through. Also, a 1 armed router is limited by it's 1 arm :) That link will be limited to 100 mb/sec (unless you move up to a 72xx or higher router, where gig is possible). So for instance if you're copying a large file between VLANs, it'd be pretty easy to use up all the bandwidth of that 100 mbit full duplex link, even if the CPU wasn't working hard on the 1 armed router. Moving to a layer 3 switch typically bumps that layer 3 device to layer 2 backplane a multi-gigabit speed connection. So if your traffic between vlans will ever exceed 100 mbit, you can either shell out huge bucks for a 72xx, or get a real QOS-friendly 3550 that is both faster and cheaper. Of course if you need WAN modules in the device that's another story. I was sent this chart a while ago listing speeds of various routers and switches: > Router Performance Specs > > Router Switching Performance - Performance based on 64 Byte packets > > PlatformProcess Fast Fast >SwitchingSwitching Switching > (PPS) (Mb/S) > --- > 1400 6004,000 2,048,000 > 16006004,000 2,048,000 > 1700 1,5008,400 4,300,800 > 25008004,400 2,252,800 > 261X 1,500 15,000 7,680,000 > 262X 1,500 25,000 12,800,000 > 265X 2,000 37,000 18,944,000 > 3620 2,000 40,000 20,480,000 > 3640 4,000 80,000 40,960,000 > 3660 12,000 120,000 61,440,000 > MC38102,000 10,000 5,120,000 > 4000 1,800 14,000 7,168,000 > 4500 5,000 40,000 20,480,000 > 4700 7,000 50,000 25,600,000 > 7120 13,000 175,000 89,600,000 > 7140 20,000 300,000153,600,000 > 7200-NPE100 7,000 100,000 51,200,000 > 7200-NPE150 10,000 150,000 76,800,000 > 7200-NPE175 9,000 175,000 89,600,000 > 7200-NPE200 13,000 200,000102,400,000 > 7200-NPE225 13,000 225,000115,200,000 > 7200-NPE300 20,000 300,000153,600,000 > 7200-NPE400 20,000 400,000204,800,000 > 7200-NSE-1 20,000 300,000153,600,000 > uBR-NPE150 10,000 100,000 51,200,000 > uBR-NPE200 13,000 150,000 76,800,000 > 7000-RP 2,500 30,000 15,360,000 > 7500-RSP2 5,000 220,000112,640,000 > 7500-RSP4 8,000 345,000176,640,000 > 7500-RSP822,000 470,000240,640,000 > Cat 2948G-L3N/A 10,000,000 5,120,000,000 > Cat 4908G-L3N/A 12,000,000 6,144,000,000 > Cat 4232-L3 N/A6,000,000 3,072,000,000 > Cat -RSM 14,000 175,000 89,600,000 > Catalyst-RSFC170,000 87,040,000 > Catalyst-RSFC/NFFCII 2,000,000 1,024,000,000 > Catalyst-MSFC (IP,IPX)15,000,000 7,680,000,000 > Catalyst-MSFC (Other)170,000 87,040,000 > Catalyst-MSFC2 (IP,IPX) 15,000,000 7,680,000,000 > Catalyst-MSFC2 (Other) 680,000348,160,000 > Catalyst-MSFC (X-bar) 30,000,000 15,360,000,000 > > NOTE: VIP2 Distributed Switching significantly increases > the performance on RSP platforms. Chuck Church CCIE #8776, MCNE, MCSE Please advice if there are any difference in the >>> >>>functionalities etc. if I >>> use 1) a L3 switch for routing between VLANs, 2) a L2 switch followed by a router for routing >>> > between VLANs. > >>>1) define "functionality" >>> >>>2) define "difference" Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=62273&t=62273 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
