Hello,
Apologies in advance if this question has been asked before, I just have managed to get a mental block.
We will be connecting a new (network centric) ACI network into our existing catalyst core which is currently VSS but will be split in the not too distant future and I'm just looking for some recommendations on how to connect ACI to legacy for when we split. The plan is to extend the EPGs from ACI into the existing LAN so I thought just to run an ether channel trunk from each catalyst into a leaf and my question is where will spanning tree block ports.
thank you in advance
Accepted Solutions
Hi @Jonathan0410 ,
The answer depends on where the Root bridge is for each particular VLAN. My picture assumes that CAT 6800-1 is the root for VLAN 10 and CAT 6800-2 is the root for VLAN 20
But one more thing: IF YOU ARE USING 802.1 STANDARD MST, you must create a special EPG that captures untagged traffic (i.e the MST BPDUs) and place the ACI leaf ports facing the CAT switches in that EPG so that the BPDUs propagate through ACI.
IF YOU ARE USING CISCO PROPRIETARY PER VLAN SPANNING TREE (or RAPID PER VLAN SPANNING TREE) then you don't need to do this because the Cisco Proprietary BPDUs come with VLAN tags of 10 or 20 and will be automatically propagated.
Hi @Jonathan0410 ,
The answer depends on where the Root bridge is for each particular VLAN. My picture assumes that CAT 6800-1 is the root for VLAN 10 and CAT 6800-2 is the root for VLAN 20
But one more thing: IF YOU ARE USING 802.1 STANDARD MST, you must create a special EPG that captures untagged traffic (i.e the MST BPDUs) and place the ACI leaf ports facing the CAT switches in that EPG so that the BPDUs propagate through ACI.
IF YOU ARE USING CISCO PROPRIETARY PER VLAN SPANNING TREE (or RAPID PER VLAN SPANNING TREE) then you don't need to do this because the Cisco Proprietary BPDUs come with VLAN tags of 10 or 20 and will be automatically propagated.
