Same VLAN across multiple distribution switches

[hdza1915]

Hi,

I have a 3 tier topology in our campus, with a redundant Core layer in the DC, Bloc #1 has 2 dist switches and some access switches, Bloc # 2 has another 2 dist switches and access switches. connections between ACC & Dist are L2 and between Dist & CORE are L3 ( static routing) The network is segmented upon 4 VLANs (assuming : 10,20 in BLOC #1 and 30,40 in BLOC #2)

We added a new Bloc (#3) also with its 2 Dist switches + the access layer, in addition to new VLANs, we need to have on the access swiches of that new Bloc the same VLANs (10 & 20)

SVIs of the existing VLANs are currently on the DIST layer.

How can I do that with that topology ? (see attached image describing the desired goal)

Thanks

[Flavio Miranda]

Hi @hdza1915 

 Add the vlan to the new Infrastructure is simple, you can just create the vlan on dist and access. Vlan ID have local significance,  which means, you can have the same vlan all over the network.

 But, this vlans on the new Infrastructure needs to have a different network and you can add new static route on cores for this vlans.

 I am not sure if that was what you are asking for. If not, please let me know

[hdza1915]

thanks for the reply @Flavio Miranda 

different network means segmentation at L3 => separated at a L2 level also

so what's the purpose of creating the same VLAN if I will assign different networks ?

thanks

[Flavio Miranda]

Actually none. It could be the same vlan ID or anything else as the vlan ID has local significance.  The most important point here is that you are not able to extend vlans between block as you use Layer3 between dist and cores.

  Then you need to rely on different subnets in order to be able to route and the vlan ID does not matter

[Martin L]

i agree; different subnets is a must but i would also have or keep different vlan IDs so there is no confusion.

Regards, ML
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[paul driver]

Hello
In theory you have a L3 access layer meaning you cannot extended the vlans across that access layer, the only way possible in your topology would be to introduce a l2 interconnect between Bloc1-Bloc3