core, dist , access

Unanswered Question
Mar 23rd, 2007

Hi all, when using the core to dist layer, is it best to use layer 3 here ?

I have this problem too.
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Amit Singh Fri, 03/23/2007 - 05:03


This is the best design practice that I always follow by making disti to core as layer. This will avoid unncessary broadcast traffic, extension of spanning-tree protocol and its traffic to core and unecceasry processing of rlayer 2 traffic at the core. This will improve the eprformace of the core and using the routing protocl you can use load-balancing and seemless traffic fail-over.

HTH,Please rate if it does.

-amit singh

carl_townshend Fri, 03/23/2007 - 05:13

so would I connect my switches to 2 core switches, and use eigrp for failover or hsrp at the cores ?

Amit Singh Fri, 03/23/2007 - 08:44

No HSRP at core for the L3 links. As every link is configured as a separate L3 subnet, just configure the EIGRP and have all the subnets advertised using EIGRP. If you are doing intervlan routing for some vlans on core switches, then run HSRP for those vlans on the core switches.

If you are getting only L3 uplinks then just use EIGRP for routing.

HTH,Please rate if it does.

-amit singh

carl_townshend Fri, 03/23/2007 - 08:47

so would I use hsrp on the dist switches, then have 2 layer 3 ports from each dist switch to say 2 core switches, 1 going to each for failover, then just advetise as usual on the dist and core switches ?

Amit Singh Fri, 03/23/2007 - 09:24

Yes Carl you are right about it.

If you have redundant distribution switches then run HSRP there and advertise all the routes via EIGRP to the whole domain.


-amit singh

walleyewiz Mon, 03/26/2007 - 14:39

I like to do Layer 3 everywhere. Simply route down to the access layer. There is no HSRP to configure--all layers are routed layers. It is nice for management too--with the exception of adding downlinks for switches, you never have to configure the core/dist switches.


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