Vlan Routing Issue

[Mokhalil82]

Hi Guys

Please see attached simple diagram. I am in the process of replacing a 6500 switch with a 6800.I need to do this migration in stages so I have connected the new switch to the old via a trunk. Next I want to move some links across but not the svi's, so i moved the port-channel for one of the areas over which had data and voice vlans (Green switch), when connected to the new switch the devices could ping the voice and data svi's that currently sit on the old core but cannot get further than that. I cannot ping other vlans either. 

Is routing required between the old and new core? I was planning to have the new core as a L2 extension to the old during the migration but cannot turn off routing on the 6800.

Thanks

[Mokhalil82]

Hi

I couldnt connect to the 6500 as its a production switch so im onle able to connect ooh. But what i did was to get a 3750 to act as the production core and plugged my laptop into the 2960x and put the SVIs on the 3750 and i still could only ping my own gatteway and not others. So i just redone the vss and rebooted the 6800 and now it worked,  managed to ping the other SVIs from my laptop.

So not sure what was going on there, seems a bit weird. But Reza and Jon, thanks for the help, really appreciate it

[Reza Sharifi]

ok, so looking at the diagram, you are routing at the access layer, because you have a /30 from each access switch to the core.  This means, the SVIs are on the access switches and not on the 6500. How many user/phone vlans do you have? Can you post "sh run" and "sh vlan" from one of the access switches?

[Reza Sharifi]

No, as long as each access switch is uplinked to both 6800 switches, no traffic will go over the VSL link. So, think of both 6800 as one logical device.

I was reading the post from you and Jon and I am still not sure if you are routing at the access layer or the access switches are just layer-2 and all the SVIs are on the 6500. From your first post, I understood that SVIs are on the 6500 and during the migration you add a layer-2 trunk link between the 6500 and 6800, and than move over one access switch at a time. If you are routing at the access layer the migration path/design needs to be changed.

[Jon Marshall]

Hi Reza

It's confusing because the access layer has been setup as L3 with a vlan specifically for routing but then a trunk connection has been used which allows the vlan for routing but also allows the data and voice vlans.

Which basically means it is all L2 as far as I can tell from the access switch to the 6500.

If the data and voice vlans had local SVIs on the access switch then yes it would need a completely different migration path but as far as I can tell all L3 is done by the 6500.

Jon

[Reza Sharifi]

Hi Jon,

Thanks for the explanation and clarification!

In this case a default route on the 6800 pointing to the old 6500 should do the work as long as he is moving the access switches with the same management IP/subnet.  And as you noted, there would be no need for a static route from the 6500 to the 6800.

Reza