Cisco to Alcatel STP

[jasonshearer]

Have a Cisco 6513 (sup720 12.2(18)SXD2) and two Alcatel Omniswitches (v4.3.3) in a triangle topology connected with LX SM gige fiber.

Having issues with spanning tree. Running PVST on the Cisco and the Alcatels are running their version of per-vlan STP. I can carry my VLANs over dot1q trunks but the Alcatels don't recognize the Cisco as the root bridge for any VLAN except for VLAN1 (when the Cisco priority is set lower) and the Cisco doesn't recognize the Alcatels as the root bridge for any VLAN except for VLAN1 (when the Alcatel priority is set lower).

I have created dummy vlans on both the Cisco and the Alcatels (VLAN4000) which is set as the native VLAN on the trunk links (allowing VLAN1 to be tagged).

This only causes a problem when the link between the Alcatels is active.

Any one have any ideas? I have tried running MST on the Ciscos and this causes a plethora of other problems. Let me know if anyone needs more info.

[brianj]

I don't think you can use PVLAN because it is Cisco Proprietary. You should be able to use PVLAN+ with dot1q trunks on the cisco devices and cst on the Alcatel though.

[milan.kulik]

I agree.

Read BPDU Formats part of

http://www.cisco.com/warp/customer/473/103.html#stp

for details.

Regards,

Milan

[Darren Ramsey]

We saw similar issues between several Alcatel 5052 and 3550, 4506, 6509, etc. We tried combinations of PVST, PVRST, and MST. Ultimately we gave up and turned STP off on completely, and preyed we didn't get a loop, until we could get rid of the Alcatel switches.