From: Larson, Chris (Contractor) (Chris.Larson@xxxxxx)
Date: Fri Dec 07 2001 - 12:19:14 GMT-3
Again, I suppose it depends on your network. Our distribution switches run
L3 services for several reasons, one of which is that much of our
distribution layer is comprised of WAN so of course we have to have layer 3
to our access routers in the various regions and states. We also have layer
3 distribution because our server farm hanging off layer 2 switches have
HSRP. There are many other factors and again it is what meets your needs.
If you look at the various campus giga network designs on Cisco you will see
they have many different "well designed" networks. Some with a L2 core and
L3 Distribution and access, some with L2 core, L2 distribution and L3
access.
Ours follows the one in Figure 8
http://www.cisco.com/warp/public/cc/so/neso/lnso/cpso/gcnd_wp.htm
<http://www.cisco.com/warp/public/cc/so/neso/lnso/cpso/gcnd_wp.htm> almost
exactly except with a larger number of devices and many more Vlans. 6 6509
in the core, several L3 WAN distrubution swiches that connect to other cores
and a few L3 for server farms and then all the access switches.
-----Original Message-----
From: Williams, Glenn [mailto:WILLIAMSG@PANASONIC.COM]
Sent: Friday, December 07, 2001 9:51 AM
To: 'Larson, Chris (Contractor)'; 'ccielab@groupstudy.com'
Subject: RE: Layer 2 Redundancy
Well, I guess, a little off the well designed network, (grin) I was thinking
a distribution layer designed layer 2 vs.. layer 3.
GW
-----Original Message-----
From: Larson, Chris (Contractor) [mailto:Chris.Larson@ed.gov]
Sent: Friday, December 07, 2001 8:38 AM
To: 'Williams, Glenn'; 'ccielab@groupstudy.com'
Subject: RE: Layer 2 Redundancy
Actually I have not heard that argument. It depends on what you are doing
and the requirements. We have a 6 switch layer 2 core that feeds our Layer 3
distribution switches and our L3 distribution swiches have layer 2
redundancy with our access switches but run HSRP to provide L3 redundancy to
the stations hanging of the layer 2 closet access switches.
I have never heard arguments against layer 2 redundancy. I believe in a well
designed high reliable network from end to end you would need a combination
of both layer 2 and layer 3 redundancy and they go hand in hand to produce a
healthy, available and efficient network.
-----Original Message-----
From: Williams, Glenn [ mailto:WILLIAMSG@PANASONIC.COM
<mailto:WILLIAMSG@PANASONIC.COM> ]
Sent: Friday, December 07, 2001 8:52 AM
To: 'ccielab@groupstudy.com'
Subject: Layer 2 Redundancy
Hi,
Is the major argument against layer 2 redundancy (vs. layer 3 & HSRP) the
potential for layer 2 loops and problems with spanning tree. So I take it
layer 3 is the best way to go in the industry.
Thanks
GW
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