[27628] in resnet
Re: SOHO WiFi routers and residential networking
daemon@ATHENA.MIT.EDU (Ryan Dorman)
Sat May 5 16:36:40 2012
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Date: Sat, 5 May 2012 16:34:53 -0400
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From: Ryan Dorman <Ryan.Dorman@blackboard.com>
To: RESNET-L@listserv.nd.edu
In-Reply-To: <20120504144324.GI16920@jadzia.mcc.ac.uk>
There are certainly cases where larger subnets are required and indeed on my own network I have some cases of that. The underlying issue is traffic containment and network segmentation. Private VLAN's, using controller based settings to inhibit P2P wireless traffic things like that... Every network is a living breathing organism and has different design needs and every engineer brings a bit of their own "style" to the table and it doesn't make it wrong.. that's a point I concede without question.
Most of my comments/suggestions are shots in the dark to be sure... packet captures at the time of "attack", debugs from when the flood control kicks in... examination of possible STP issues... this sounds like one that's going to take some time to nail down.
Sheila - Have they ever opened a TAC case with Cisco on this?
-rd
-----Original Message-----
From: Resnet Forum [mailto:RESNET-L@LISTSERV.ND.EDU] On Behalf Of Mike Richardson
Sent: Friday, May 04, 2012 7:43 AM
To: RESNET-L@LISTSERV.ND.EDU
Subject: Re: SOHO WiFi routers and residential networking
On Fri, May 04, 2012 at 11:25:55AM +0000, Osborne, Bruce W wrote:
> I slightly disagree. Ryan.
>
>
> Dealing with many /24s in a large wireless deployment can get unwieldy.
>
>
> Here at Liberty University,, we use /23 that are twice the size of /24.
> Our wireless broadcast traffic is still pretty low. At least, it is
> better than we used /20 subnets for wireless. We are doing multicast
> IPTV on the /23s. We blocked it when we were using /20.
I agree. Our (Aruba) system uses VLAN pooling to balance usage across a number of VLANs and we have one subnet per VLAN. The balancing is done by MAC hash but isn't perfect. In an ideal world one big subnet would be the most efficient way of doing it, from an address usage perspective. Small subnets means a need for lots of VLANs to ensure that particular subnets aren't statistically likely to fill. Currently we have 30 x /23 and it seems to work ok.
Mike
--
Mike Richardson
Networks (network@manchester.ac.uk)
IT Services, University of Manchester
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