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We have a couple of 6509's that are setup for load-balancing/failover...both have identical vlans with one being a standby and the primary. We're running IEGRP for routing.

My question is, we have a 3750 which all the workstations plug in it generally recommended to set up trunks from the 3750 to the 6509s and have the 6509s be the gateway, or is it better to set up layer 3 links, have the 3750 be the gateway and let EIGRP make all the routing decisions to the 6509s?

Correct Answer by lamav about 9 years 4 months ago

My pleasure...glad I can help.

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Overall Rating: 5 (2 ratings)
lamav Sat, 02/16/2008 - 18:51
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The trend these days is to deploy a routed access layer, if the application permits, of course. The reasons for doing so are primarily:

1. To decrease convergenece time in the event of an outage, since routing protocols do converge faster than STP.

2. Minimize the chance of suffering a layer 2 loop, since the switched environemnt will be greatly reduced in size. This is called L3 isolation

3. Traffic load banlancing across equal cost multiple paths -- what Cisco refers to as ECMP.

If you go with the routed access layer design, you must know that you cannot span the user VLANs across the distro/core layer. The VLAN will be confined to the local access switch. If all the users terminate their connections on the same switch, then this could be the way to go.

If you are deploying a collapsed core, i would definitely go with the routed access design.

A switched access layer with L2 trunks uplinked to a routed distro layer does provide more scalabiliaty, especially in the data Center (server farm). But I see your concern is with the campus/user environment.

Feel free to post more concerns/questions. Hope my ramblings helped.


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lamav Sat, 02/16/2008 - 19:55
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My pleasure...glad I can help.


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