# Monitoring GRE Tunnel Information

#### Purpose

Display information about GRE tunnels. The state keyword displays tunnels that are in a specific state: disabled, down, enabled, not-present, or up. The ip keyword to display tunnels associated with an IP address. To display information about a specific tunnel, include the name of the tunnel. To display information about tunnels on a specific virtual router, include the name of the virtual router.

#### Action

To display information about GRE Tunnel policy lists:

    host1#show gre tunnel detail tunnelGre50
    GRE tunnel tunnelGre50 is Down
    Tunnel operational configuration
      Tunnel mtu is '10240'
      Tunnel source address is '0.0.0.0'
      Tunnel destination address is '0.0.0.0'
      Tunnel transport virtual router is source
      Tunnel checksum option is disabled
      Tunnel sequence number option is disabled
      Tunnel up/down trap is enabled
      Tunnel-server location is 6/0
      Tunnel administrative state is Up
    Statistics    packets        octets       discards   errors
      Data rx     0              0            0          0
      Data tx     0              0            0          0
    GRE tunnel policy input routeGre25
      classifier-group gre6 entry 1
         0 packets, 0 bytes
         traffic-class best-effort
         mark 4 mask 255
    GRE tunnel policy output routeGre35
      classifier-group gre14 entry 1
         0 packets, 0 bytes
         traffic-class best-effort
         mark 4 mask 255

#### Meaning

Table 36 lists the show gre tunnel command output fields.

Table 36: show gre tunnel Output Fields

Field Name | Field Description
--- | ---
GRE tunnel policy input | Policy for outbound traffic
GRE tunnel policy output | Policy for inbound traffic
traffic-class | Name of traffic class
classifier-group | Name of classifier group
entry | Identifier for the entry in the classifier group
packets | Number of packets
bytes | Number of bytes
mark | ToS byte setting for the classifier control list
mask | Mask value corresponding to the ToS

#### Related Documentation

- show gre tunnel