VSS From core to Distribution

nataymenesa · ‎10-28-2014

Hello

i used to have native L3 connection from core to distribution and distribution to access was L2. The distribution was our demarcation point b/n L3 AND L2.

how do i introduce vss in this scenario, we still want the distribution to be our demarcation point for L2 & L3 Traffic.

i have two 6509 with sup720-10g as my core and two 4500x switches as my distribution.

Joseph W. Doherty · ‎10-28-2014

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How you might use VSS would be to have your pair of 4500s use VSS (if they're able). This would allow active L2 redundancy. E.g. uplink port-channel from edge switches with a link to each 4500.

Keep L3 between the 4500s and 6509s, don't VSS the 6509s. (You could also VSS pair the 6509s, but unless you believe there's a really good reason to do so, again, I suggest you don't. VSS is really more of a benefit for L2 than it is for L3.)

a12288 · ‎10-28-2014

You can do VSS on distribution layer and port channel down to access layer switches, this port channel will carry L2 VLAN(s) and will be terminated on distribution layer (C4500x).

Since now you have ONE distribution switch so you only need 2 x L3 links between your distribution switch to your core C6509 switches, while before VSS you would have 4 x L3 links between distribution and core.

What we did is to covert 4 x L3 /30 links between distribution and core switches into 2 x L3 /30 port channels. For example:

1) Core1.Port-Channel1 & Core2.Port-Channel1 <==> Dist.Port-Channel1

2) Core1.Port-Channel2 & Core2.Port-Channel2 <==> Dist.Port-Channel2

There is no benefits to introduce VSS into core.

Leo