SSTP BPDU

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Sep 3rd, 2008
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Hi All,


I want to know what is SSTP BPDU. Is it Cisco's propreitary one or standard. What is the significance of SSTP BPDU?


I ve a switch and router connected as 802.1q trunk interface. Suddenly i received the below logs:


Aug 20 14:02:40.506 IST: %SPANTREE-2-RECV_PVID_ERR: Received BPDU with inconsistent peer vlan id 240 on FastEthernet0/20


VLAN943.

Aug 20 14:02:40.506 IST: %SPANTREE-2-BLOCK_PVID_PEER: Blocking FastEthernet0/20 on VLAN0240. Inconsistent peer vlan.

Aug 20 14:02:40.506 IST: %SPANTREE-2-BLOCK_PVID_LOCAL: Blocking FastEthernet0/20 on VLAN0943. Inconsistent local vlan.

Aug 20 15:35:03.411 IST: %SPANTREE-2-RECV_PVID_ERR: Received BPDU with inconsistent peer vlan id 240 on FastEthernet0/20


VLAN943.


Does it mean that the switch receives a SSTP BPDU with VLAN 240 but it does not match with VLAN 943 and hence putting the VLAN 943 in BLOCKING mode in STP.


Any help is appreciated..


Thanks in advance


regards,

Arun

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satish_zanjurne Wed, 09/03/2008 - 23:03
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Hi,


STP BPDU is IEEE 802.1d standard.


Spanning-Tree Protocol implements the 802.1D IEEE algorithm by exchanging BPDU messages with other switches to detect loops, and then removes the loop by shutting down selected bridge interfaces. This algorithm guarantees that there is one and only one active path between two network devices.


Hi, you receive this message because, either of the side of trunk has mismatched VLAN.


You would be able to resolve this if you verify & reconfigure the mismatched/inconsistent vlan.


HTH..rate if helpful..

Giuseppe Larosa Thu, 09/04/2008 - 00:27
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Hello Arun,

Cisco PVSTP+ BDPUs contain the associated vlan in a field.

This allows the peer switch to perform a sanity check by comparing the vlan-id field in the BPDU with the the vlan-id of the 802.1Q tag that was in the frame.

In this case you see BPDUs with vlan-id 240 received with an 802.1Q vlan tag of 943 and viceversa.

Verify if there is a mismatch of native vlan on the two sides.

Another possibility is that you have configured the router to bridge frames on both vlans 240 and 943 and so is sending back frames on the trunk port.


Hope to help

Giuseppe

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