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Connecting Nexus 5548UP to Nortel switch

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

2 REPLIES 2
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Beginner

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.  

Highlighted
VIP Expert

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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