Catalyst 520 STP problem

[baxta2712]

Hello could anyone help me? I have got 2 catalist 520 series switch on my network and they have created its own autonomous RSTP and one of them is root bridge and they are not communicating with other cisco switches could anyone tell me what could be the problem?

[cadet alain]

Hi,

provide a topology diagram( not visio please) then we'll see which more infos we need to solve your problem.

Regards.

Alain.

[baxta2712]

Here is network diagram, I think the problem is that ESW520 does not understand pvst, and they did not accept BPDU- from CE500

[lgijssel]

Interesting scenario. You probably have a point; the ESW520 supports only the IEEE standard versions of STP:
802.1d STP

802.1w RSTP

802.1s MST

From the STP point of view, IEEE 802.1D is not VLAN-aware and IEEE 802.1Q is VLAN-aware, but it uses a single STP instance for all VLANs. That is, if the port is blocking then it is blocking for all VLANs on that port. The same is true for forwarding.
This list shows how PVST+ interoperates with IEEE 802.1Q or IEEE 802.1D, if the Native VLAN on an IEEE 802.1Q trunk is VLAN 1:
• VLAN 1 STP BPDUs are sent to the IEEE STP MAC address (0180.c200.0000), untagged.
• VLAN 1 STP BPDUs are also sent to the PVST+ MAC address, untagged.
• Non-VLAN 1 STP BPDUs are sent to the PVST+ MAC address (also called the Shared Spanning Tree Protocol [SSTP] MAC address, 0100.0ccc.cccd), tagged with a corresponding IEEE 802.1Q VLAN tag.

If the Native VLAN on an IEEE 802.1Q trunk is not VLAN 1:
• VLAN 1 STP BPDUs are sent to the PVST+ MAC address, tagged with a corresponding IEEE 802.1Q VLAN tag.
• VLAN 1 STP BPDUs are also sent to the IEEE STP MAC address on the Native VLAN of the IEEE 802.1Q trunk, untagged.
• Non-VLAN 1 STP BPDUs are sent to the PVST+ MAC address, tagged with a corresponding IEEE 802.1Q VLAN tag.
Note: Native VLAN STP BPDUs are sent untagged.

Link where I found this:

http://www.cisco.com/en/US/tech/tk389/tk621/technologies_tech_note09186a00801d11a0.shtml#topic1

My first guess: You may be blocking vlan1 on the trunk towards the ESW520 switches.

regards,

Leo