12-16-2012 05:09 PM - edited 03-07-2019 10:38 AM
Hello,
I have an old network composed of many Nortel switches. Now, we have built new core LAN infrastructure with Nexus 7000, Nexus 5548UP, and Nexus 2000. We would like to move all devices from Nortel to Cisco. Since it will take some time, we have to connect Nortel to Cisco untill all devices are migrated. Nortel uses STG. Cisco uses MST. Once we connect both switches, ports on Cisco get blocked with message:
Mst Instance Role Sts Cost Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
MST0000 Desg BKN*200 128.4098 (vPC) P2p Bound(PVST) *PVID_Inc
MST0001 Desg BLK 200 128.4098 (vPC) P2p Bound(PVST)
or
Mst Instance Role Sts Cost Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
MST0000 Desg BKN*200 128.4098 (vPC) P2p Bound(STP) *PVID, PVST_PEER_Inc
MST0001 Desg BKN*200 128.4098 (vPC) P2p Bound(STP) *PVST_PEER_Inc
depending on how we tried to configure uplink ports (spanning-tree mst simulate pvst)
Since Cisco uses MST, and will be the core, the root has to be there, so we setup low priority for Nexus switches and enabled rootguard on downstream ports.
Is there any recommendation for connecting Nortel STG with Cisco MST? Maybe the solution is to change STG to MST on Nortel, but noone is brave enough to do it in existing production network :-) Any advice will be appreciated.
Best regards,
Krzysztof
09-16-2016 09:32 AM
Hi there,
Please let me know if you were able to resolve this issue. We are experiencing similar symptoms connecting a nortel switch (5520) to a pair of Cisco 9372 switches allowing 2 VLANS.
09-16-2016 10:39 AM
Hello Krzysztof,
if you use Rapid-PVST on the Cisco core (whch is actually the default) instead of MST, you could even disable spanning tree alltogether on the Nortel switches.
Check out this document for details:
http://www.michaelfmcnamara.com/files/NN48500-588_1.1_Nortel_Cisco_Interoperability.pdf
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