# Layer2 Protocol Tunneling

## Navigation

Right-click a port and then select Configure > Layer2 Protocol Tunneling.

From this dialog box, you can specify Layer2 protocol tunneling settings for the ports on this device. Note that this dialog box is available only on:

> devices running Cisco IOS release 12.2(18)EW or later

> interfaces that support tunneling

Tunneling allows separate local networks, connected through an ISP, to be recognized as one VLAN. This is possible because packets are transported by the ISP from one network to another, giving the impression that the two networks are really one network. Tunneling is supported by the following Layer2 protocols: Cisco Discovery Protocol (CDP), VLAN Trunk Protocol (VTP), and Spanning Tree Protocol (STP).

The following information is displayed:

> CDP:

> CDP Tunneling (cltcTunneledProtocolType)

> CDP Drop Threshold (cltcTunnelDropThreshold)

> CDP Shutdown Threshold (cltcTunnelShutdownThreshold)

> VTP:

> VTP Tunneling (cltcTunneledProtocolType)

> VTP Drop Threshold (cltcTunnelDropThreshold)

> VTP Shutdown Threshold (cltcTunnelShutdownThreshold)

> STP:

> STP Tunneling (cltcTunneledProtocolType)

> STP Drop Threshold (cltcTunnelDropThreshold)

> STP Shutdown Threshold (cltcTunnelShutdownThreshold)

### CDP:

### CDP Tunneling (cltcTunneledProtocolType)

Indicates whether CDP PDU tunneling mode is enabled.

### CDP Drop Threshold (cltcTunnelDropThreshold)

Indicates the drop threshold for tunneled CDP PDUs on an interface. After reaching this value, the interface drops CDP PDUs. A value of zero indicates that no limit is set. This field is disabled when CDP tunneling mode is disabled.

### CDP Shutdown Threshold (cltcTunnelShutdownThreshold)

Indicates the shutdown threshold for tunneled CDP PDUs on an interface. After reaching this value, the interface shuts down. A value of zero indicates that no limit is set. This field is disabled when CDP tunneling mode is disabled.

### VTP:

### VTP Tunneling (cltcTunneledProtocolType)

Indicates whether VTP PDU tunneling mode is enabled.

### VTP Drop Threshold (cltcTunnelDropThreshold)

Indicates the drop threshold for tunneled VTP PDUs on an interface. After reaching this value, the interface drops VTP PDUs. A value of zero indicates that no limit is set. This field is disabled when VTP tunneling mode is disabled.

### VTP Shutdown Threshold (cltcTunnelShutdownThreshold)

Indicates the shutdown threshold for tunneled VTP PDUs on an interface. After reaching this value, the interface shuts down. A value of zero indicates that no limit is set. This field is disabled when VTP tunneling mode is disabled.

### STP:

### STP Tunneling (cltcTunneledProtocolType)

Indicates whether STP PDU tunneling mode is enabled.

### STP Drop Threshold (cltcTunnelDropThreshold)

Indicates the drop threshold for tunneled STP PDUs on an interface. After reaching this value, the interface drops STP PDUs. A value of zero indicates that no limit is set. This field is disabled when STP tunneling mode is disabled.

### STP Shutdown Threshold (cltcTunnelShutdownThreshold)

Indicates the shutdown threshold for tunneled STP PDUs on an interface. After reaching this value, the interface shuts down. A value of zero indicates that no limit is set. This field is disabled when STP tunneling mode is disabled.