Introduction
The error message can read:
SPANTREE-2-RECV-BAD-TLV: Received SSTP BPDU with bad TLV on [chars] [chars].
Explanation
This message means that the listed interface received an SSTP BPDU that was missing the VLAN ID tag. The BPDU is discarded. [chars] is the interface that received the SSTP BPDU.
Each SSTP-addressed BPDU has a Tag-Length-Value (TLV) appended to it. This TLV contains the VLAN ID of the spanning tree to which the BPDU belongs and is used in order to check the Port VLAN ID (PVID).
All untagged frames are assigned to the LAN specified in the PVID parameter. When a tagged frame is received by a port, the tag is respected. If the frame is untagged, the value contained in the PVID is considered as a tag.
In some cases, these error messages occurs due to native vlan inconsistency on the interfaces on each end of the 802.1Q trunk connection.
Action
If the SSTP-addressed BPDU does not have an 802.1Q tag, that is, if it originates from the PVID of the sender 802.1Q port, it still contains a TLV. The TLV contains the PVID of the sender port, which the receiver compares with the PVID of the receiver port. If these two values do not match, the port is put into a Blocking state due to the PVID inconsistency.
Issue the show interfaces [interface-number] switchport command in order to verify that the configuration of the native VLAN ID is consistent or same on either side of the interfaces.
Show Interfaces Switchport command
To display the administrative and operational status of a switching (nonrouting) port, use the show interfaces switchport command.
show interfaces [interface-id] switchport [module mod]
Syntax Description
interface-id | (Optional) Interface ID for the physical port. |
| module mod | (Optional) Limits the display to interfaces on the specified module; valid values are from 1 to 6. |
Defaults
This command has no default settings.
Command Modes
Privileged EXEC mode
Examples
This example shows how to display switch-port information using the begin output modifier:
Switch# show interfaces switchport | include VLAN
Name: Fa5/6
Access Mode VLAN: 200 (VLAN0200)
Trunking Native Mode VLAN: 1 (default)
Trunking VLANs Enabled: ALL
Pruning VLANs Enabled: ALL
Switch#
This example shows how to display switch-port information for module 1:
Switch# show interfaces switchport module 1
Name:Gi1/1
Switchport:Enabled
Administrative Mode:dynamic auto
Operational Mode:down
Administrative Trunking Encapsulation:negotiate
Negotiation of Trunking:On
Access Mode VLAN:1 (default)
Trunking Native Mode VLAN:1 (default)
Administrative private-vlan host-association:none
Administrative private-vlan mapping:none
Operational private-vlan:none
Trunking VLANs Enabled:ALL
Pruning VLANs Enabled:2-1001
Name:Gi1/2
Switchport:Enabled
Administrative Mode:dynamic auto
Operational Mode:down
Administrative Trunking Encapsulation:negotiate
Negotiation of Trunking:On
Access Mode VLAN:1 (default)
Trunking Native Mode VLAN:1 (default)
Administrative private-vlan host-association:none
Administrative private-vlan mapping:none
Operational private-vlan:none
Trunking VLANs Enabled:ALL
Pruning VLANs Enabled:2-1001
Switch#
This example shows how to display the status of native VLAN tagging on the port:
Switch# show interfaces f3/1 switchport
show interface f3/1 switchport
Name: Fa3/1
Switchport: Enabled
Administrative Mode: private-vlan promiscuous
Operational Mode: private-vlan trunk secondary
Administrative Trunking Encapsulation: negotiate
Operational Trunking Encapsulation: dot1q
Negotiation of Trunking: On
Access Mode VLAN: 1 (default)
Trunking Native Mode VLAN: 1 (default)
Administrative Native VLAN tagging: enabled
Voice VLAN: none
Administrative private-vlan host-association: none
Administrative private-vlan mapping: none
Administrative private-vlan trunk native VLAN: 1
Administrative private-vlan trunk Native VLAN tagging: enabled
Administrative private-vlan trunk encapsulation: dot1q
Administrative private-vlan trunk normal VLANs: 1
Administrative private-vlan trunk associations: none
Administrative private-vlan trunk mappings:
10 (VLAN0010) 100 (VLAN0100)
Operational private-vlan:
10 (VLAN0010) 100 (VLAN0100)
Trunking VLANs Enabled: ALL
Pruning VLANs Enabled: 2-1001
Capture Mode Disabled
Capture VLANs Allowed: ALL
Unknown unicast blocked: disabled
Unknown multicast blocked: disabled
Appliance trust: none
Switch#
For further assistance and support, open a service request with the TAC Service Request Tool.
Reference
