interesting points, and well taken. if one takes VLANs to be synonymous with subnets then sure.
your 10.0.0.0/16 thought reminds me of the good old days when the Xylan marketing team was out hawking their "flatten the network" religion. In this respect I am a traditionalist - route where you can, and bridge where you must. yeah, I keep forgetting that Windows does some broadcasting, but recall that I come out of the brokerage industry, where broadcast was a necessity. How else would quote machines work? Upwards of 80-90% of our LAN traffic during market hours was broadcast. So how much broadcast traffic can a couple hundred windoze boxes really create, and just how badly does that really effect network performance? Particularly if you are running a fully switched environment, or even in a hubbed environment, assuming 12-24 port hubs? When I was young and foolish, I ran my network on daisy chained 48 port hubs, and I think I got up to around 125 stations and printers before I regretted my foolishness. This was in that self same brokerage firm, with the outrageous broadcast traffic. I know a Major Bank where they at one time ran segments of 700-100 end stations. And survived to a certain degree. ( although they were the masters of broadcast control :-> ) As I said, your points are well taken. the application drives most things, but the architecture surely drives others. thanks. Chuck -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Carroll Kong Sent: Wednesday, October 24, 2001 5:20 PM To: [EMAIL PROTECTED] Subject: RE: MAC address and VLANs [7:23950] I cut a large portion of this the previous message. My argument in that is that, we DO have broadcasting monsters. It is known as Windows based PCs. NetBIOS over TCP/IP, announcing wondrous information and trying to get information so they can perform their wonderful elections and create master browsers. Trying to resolve NetBIOS names so they can find their friendly PDC or BDC of the day. Or how about WINS and it's excellent method of doing discerning which names goes where. All automagic at the cost of the network. While what you speak is true, and in a network bereft of windows mongers, I would agree, I think that in a modern system you can still run into issues. According to your logic, it seems like you would be ok with forging a 10.0.0.0/16 network and chaining along switches instead of breaking them into subnets along with their accused VLANs. I suppose with enough good 10/100 Switches you are ok. This might be problematic on a 10BaseT network as the broadcast snowball into huge gobs of bandwidth draining gunk. (I guess this rolls into the non-modern network though) I have a client who used some 10 base hubs too, and just band aided it with a few switches here and there. NetBIOS over TCP/IP sends broadcasts quite frequently. I almost dare say within a minute. CPUs can vary, and there is always the aging 486 on the fringe. I guess ultimately on a solid 10/100Base Switched network you do pose a good point. However, do you think that a nasty 10.0.0.0/16 network might be going a bit too far even with the latest technology? In that case, we can argue, who really needs routing protocols internally? Just slap up the good old super flat network and have a default gateway and rarely call in the big dogs to make changes. Just throw a few statics to the few other "super" flat networks and we got an enterprise solution. :) Not trying to pick a bone with you. I agree with you, but I am curious where do you feel is the threshold? You say until it breaks, but I want to deploy a better solution before we get to that. At 07:52 PM 10/24/01 -0400, Chuck Larrieu wrote: >hooray for you, PO! you are absolutely correct. > >In military science, it is well known that military establishments enter any >war prepared to fight the previous one. In these days of DSL to the home >desktop, 100 megabit to the office desktop, ATM backbone WANS, and HTML >based applications, we networking students study various means of eking out >another packet or two on 56K links. Anyone here see the point of ISDN backup >for DS3 links? ;-> > >Your forward thinking is commendable. > >Chuck > >-----Original Message----- >From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of >Priscilla Oppenheimer >Sent: Wednesday, October 24, 2001 11:51 AM >To: [EMAIL PROTECTED] >Subject: Re: MAC address and VLANs [7:23950] > > >The multi-VLAN feature that Leigh Anne mentioned might solve your problem. >The Cisco switch port could be associated with two VLANs that way. You >didn't say which switch you have, and this feature may not be available on >all Cisco switches, though. > >Assuming that you don't want to upgrade the little switch to one that does >802.1Q or ISL, another somewhat radical fix to the problem might be to not >use VLANs. My philosophy is that once VLANs get to the point of causing >more problems then they fix, I eliminate them. ;-) > >One of the main things VLANs were supposed to fix was excessive broadcasts >causing too many CPU interruptions on numerous workstations in a large, >flat, switched network. > >Lately I have taken to making the controversial statement that this problem >doesn't exist on many modern networks. These days workstations have >amazingly fast CPUs. They are not bogged down by processing broadcasts. >Also, as we eliminate older "desktop" protocols such as AppleTalk and IPX, >what is still sending broadcasts? An ARP here or there is not a big >problem. And ARPs don't actually happen that often. A PC keeps the >data-link-layer address of its default gateway and other communication >partners for a long time. > >Also, a lot of PC NICs used to be stupid about multicasts and interrupt the >CPU for irrelevant multicasts for which the PC was not registered to >listen. I bet that bug has been fixed by now. > >VLANs have other benefits (security, dividing up management and >administrative domains, etc.) But if broadcasts are the issue, one should >ask: > >Which protocol send broadcasts and how often? >How fast are the CPUs? > >And that is my latest harangue against my least favorite LAN technology >(VLANs!) > >Priscilla > >_______________________ > >Priscilla Oppenheimer >http://www.priscilla.com -Carroll Kong Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=24079&t=23950 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
