From: Conte, Charles (Charles.Conte@nasdaq.com)
Date: Tue Feb 01 2005 - 12:25:02 GMT-3
Super Thanks! Roger do you have the link to the Networkers
slide show. I still agree with minimizing the spanning-tree, because of
the potential of L2 related issues.
I attached the two comparisons that got lost when I initially
attached, and I hope you can take a look at the topology and provide
more opinions based on the picture. Thanks so much for the reply!
Charles
-----Original Message-----
From: McNeace, Roger [mailto:RMcNeace@ciena.com]
Sent: Tuesday, February 01, 2005 9:54 AM
To: 'Scott Morris'; 'Brant I. Stevens'; 'asadovnikov'; Conte, Charles;
ccielab@groupstudy.com
Subject: RE: Simple Design Question
In my campus network I have pushed L3 to the access layer. Yes it limits
the use of VLAN's, but I only need a few localized VLAN's for users
anyway. In the datacenter I kept it L2 because I needed the flexability
to span VLAN's across multiple switches. Like Scott mentioned you can
tune IGP timers to give u sub-second convergence and I get load balance
my traffic across both links. Yes I could load balance at L2 but most of
my users are on one VLAN. For me I like to keep my STP domains as small
as possible. Also for your L2 network make sure u turn of any auto
negociation DTP, pagp, etc add to convergence. If you went to
networkers and have acces to the online presentations they have a good
slide show on L2 vs L3 in a campus network.
Roger McNeace CCIE#12777
Prinicipal Network Engineer
Ciena Corporation
410-694-5805
rmcneace@ciena.com
-----Original Message-----
From: Scott Morris [mailto:swm@emanon.com]
Sent: Tuesday, February 01, 2005 9:33 AM
To: 'Brant I. Stevens'; 'asadovnikov'; 'Conte, Charles';
ccielab@groupstudy.com
Subject: RE: Simple Design Question
On the flip side, you can do OSPF fast hellos and make things equal to
rapid spanning tree!
Scott Morris, MCSE, CCDP, CCIE4 (R&S/ISP-Dial/Security/Service Provider)
#4713, JNCIP, CCNA-WAN Switching, CCSP, Cable Communications Specialist,
IP Telephony Support Specialist, IP Telephony Design Specialist, CISSP
CCSI #21903 swm@emanon.com
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Brant I. Stevens
Sent: Tuesday, February 01, 2005 1:15 AM
To: asadovnikov; 'Conte, Charles'; ccielab@groupstudy.com
Subject: Re: Simple Design Question
I happen to disagree with this direction for the following reasons:
1. Using an IGP as opposed to L2 trunking for an access-to-distribution
link can actually INCREASE reconvergence time, especially when you
consider the performance of Rapid-PVST and 802.1w. The only exception
I've seen to this is using EIGRP stub areas @ each access switch, but
that means you have to run EIGRP, as opposed to OSPF.
2. You will no longer be able to have the same VLAN spread across
multiple switches (short of using software bridging, which defeats the
purpose of using switches.)
I agree that reducing reliance on STP (even if you could, NEVER disable
it... =)) is always a good idea, but I think L3 to the closet eliminates
some of the benefits that VLANs provide.
On 02/01/2005 12:57 AM, "asadovnikov" <asadovnikov@comcast.net> wrote:
> I like the approach. If access switches are L3 capable you should run
> them as routers not switches. Although there are always corner cases
> when L2 may be better option, I strongly agree that benefits of
> avoiding L2 generally greater then any potential downside.
>
> Best Regards,
> Alexei
>
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf
> Of Conte, Charles
> Sent: Monday, January 31, 2005 7:29 PM
> To: ccielab@groupstudy.com
> Subject: OT:Simple Design Question
>
> Hello,
>
>
>
> If MSFC's are available at the access-layer, can anybody
> tell me why we wouldn't run L3 to the access layer if the primary and
> secondary access switches are available in convenient locations? Also
> for the attached gifs can anybody provide any opinions on why one
> wouldn't extend L3 to the access instead of having L2 only Access
> switches [Example 1 L3] V.S. [Example 2 L2]? I like avoiding L2 in
> any situations that I can. I can understand if the requirement is to
> have the vlan available at every switch to go with example 2, but if
> not it wouldn't make sense to extend L2 everywhere. Any opinions
appreciated!
> Thanks!
>
>
>
> Charles
>
> [GroupStudy removed an attachment of type image/gif which had a name
> of example_gif_2.gif]
>
> [GroupStudy removed an attachment of type image/gif which had a name
> of example_gif_1.gif]
>
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