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Cisco 2950G-24 does not do 802.1s with Omnicore Switch

A Cisco 2950G-24-EI switch is directly attached to an Alcatel Omnicore 5022 which is configured as the Root Bridge for spanning-tree. The 2950G and the Omnicore are configured to run 802.1s spanning-tree. However, the 2950G cannot see the Omnicore as the Root Bridge and so 802.1s is not running between the two and so layer 2 loops are an issue. Has anyone come across interoperability issues for 802.1s between Alcatel and Cisco?

  • Other Network Infrastructure Subjects
Cisco Employee

Re: Cisco 2950G-24 does not do 802.1s with Omnicore Switch

We have seen issues with 2950/3550 incompatibility issues with MSTP implementation of 3rd party switches. Cisco's MST implementation is a pre-standard implementation because the software

was created before the 802.1s standard was officially adopted. We plan to implement the 802.1s standard in a future software release. Currently there is no workaround. There is a bug filed and can be seen on CCO at

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