This is sort of a continuation from a post from yesterday.
I have a switch that is configured with multiple vlans, but I want to focus on the data and voice vlans for now.
The data vlan is 341 and the voice vlan is 546.
I have a lot of L2 switchports configured to support MAVP interfaces for PCs and Avaya phones.
This switch has an L2 uplink (trunk) that carries this vlan traffic and others to a 6513 switch.
All pretty straightforward until this point...
What I dont understand is why this 4510 has routed, SVIs configured on it for these vlans -- and for the others, too, actually -- when the uplink to the 6513 is a L2 trunk?
I dont get it.
I will attach the config. It doesnt make sense to me.
The only thing I can think of is that the designer decided to have a L2 uplink as well as a routed connection to the 6513, and that the routed connection was created the old way (before the advent of IOS-based L3 switches with routed interface capability) using SVIs and placing an access or trunk port in that vlan(s) to create a simulated routed connection.
But why do it that way (perhaps he is th eonly one who could answer that) and why both L2 and L3 uplinks? This is an access layer switch going to a routed collapsed core for this site.
The L2 trunks allow you to share the L2 Vlans. If you don't do that, then each switch will have separate L2 domain.
If you go with L3 isolation, then you need to configure a different IP subnet on the 6500 and a separate IP subnet on the 4500.
Say, you have devices roaming and connecting in either the 6500 or 4500 but they need to be on X same subnet, then the L3 isolation design isn't the best.
Again, the current design isn't a rare design and actually is the most common design out there.
There are plenty of threads on this forum on the pros/cons on the L2 vs L3 switch design. A quick search should turn up some useful results.
No, you aren't being a pain :)