Avaya ERS 8600 cluster to Cisco 2960 stack rstp

[Darius]

Hi,

We have ERS 8600 cluster connected to Cisco 2960 stack.
We have some VLAN's configured and it works till we use one cable in between sack and cluster. We have no VLAN 1 on this connection.
On ERS we have enabled rstp, on Cisco is PVST.

As soon as I connect second cable to Cisco I'm loosing connection at all(there probably some loop)
I'm not sure what I need to change in ERS configuration to get it .
I have read through NN48500-604 "PVST+ Technical Configuration Guide" but I can't find clear answer what I must to do.

Does some one use similar configuration and can share experience?

Regards,
Darius

[Telair]

Hi Darius.  Are you routing between the 8600's and the 2960's or just running VLAN's and switching between them?

[Darius]

I'm bit confused on English expressions.
We have two VLAN's
On Cisco stack side we have ip address assigned only to one VLAN, other VLAN is without IP address.
On ERS side we are running VRRP and routing VLAN's through ERS to other networks.

Hope this helps to help me .

Darius

[Telair]

If you are connecting together multiple links you have two good options on how to do it.

1) Use Avaya's MLT/SMLT and Cisco's Etherchannel.  Avaya's MLT/SMLT technology and Cisco's Etherchannel are compatible and can be used to connect the two without causing a loop.

2) LACP (802.3ad) can be used on both Cisco and Avaya to create a loop-free LAG group.

It sounds like you are just connecting two cables between the devices and hoping spanning-tree sorts out which one to use.  While that can work, it's slow and can cause delays as spanning-tree figures out who to block.

Does that help you?

[Darius]

For me It looks the simples way to use rstp. And according documentation it should work.

Previously we was used HP switches instead of Cisco and it was OK.