[c-nsp] SPANTREE-SP-2-RECV_BAD_TLV

[Jean-Christophe Varaillon]

Hi,

6509_A----Ethernet_SW_Nortel_A-...-Ethernet_SW_Nortel_B----6509_B

>From the logs of 6509_A, I get the following message (I got 12 of them in 24
hours):
------
Feb  5 08:38:32 6509_A: %SPANTREE-SP-2-RECV_BAD_TLV:
Received SSTP BPDU with bad TLV on GigabitEthernet1/31 VLAN21.

Feb  5 08:38:32 6509_A: %SPANTREE-SP-2-RECV_BAD_TLV:
Received SSTP BPDU with bad TLV on GigabitEthernet1/31 VLAN60.
------

>From Cisco it means that:
"The specified interface has received a Shared Spanning Tree Protocol BPDU
that was missing the VLAN ID tag".

So the 6509_A received an untagged BPDU on its 802.1q trunk port and this
packet has been dropped.

Why did the 6509_A receive such an untagged BPDU?

My 0.002: BPDU about native vlan are never tagged. Since the 6509_B is
properly configured, it has to come from the Nortel switch_A. It is possible
that the Nortel switch_A port is configured as trunk with a different native
vlan id than the 6509_A.

--> Is there any other reasons?

Both 6509 are in PVST+ mode, both ports are configured as trunk with 802.1q,
with same native vlan (vlan 1, yes I know this is not a good idea...) and
only 3 specific vlans are allowed on this trunk.

--> Given the non redundant topology, would you safely ignore these
messages?

I will most certainly contact the administrator of the Nortel and check for
mis-configuration anyway.

Cheers.

Christophe