Configuration Tasks

To configure an IP tunnel:

1. Create or select a physical or loopback interface.

   This interface acts as an anchor for the source of the tunnel.

2. Assign an IP address to the physical or loopback interface.
3. Create a tunnel interface.
4. Set the source address for the tunnel.
5. Set the destination address for the tunnel.
6. (Optional) Enable error checking across a GRE tunnel.
7. Set the maximum transmission unit (MTU) size for the tunnel.

   Note: On SM interfaces, issue only the commands listed below. Do not configure protocols such as Multilink PPP or Multilink Frame Relay on SM interfaces.

interface tunnel

• Use to create an IP tunnel interface.
• Specify the type and name of the tunnel you want to create.
• You can use the transport-virtual-router keyword to establish the tunnel on a virtual router other than the current virtual router.
• Example

  host1(config)#interface tunnel dvmrp:boston-tunnel-1 transport-virtual-router boston

• Use the no version to remove the tunnel.

  Note: When you delete a virtual router that has been configured as a transport virtual router for a DVMRP tunnel, the show configuration output displays No Router for the transport virtual router. To remove the DVMRP tunnel interface, simply omit any reference to the transport virtual router. For example, to delete interface tunnel dvmrp:boston-tunnel-1 transport-virtual-router No Router from the configuration, issue the command, no interface tunnel dvmrp:boston-tunnel-1. bws: added @ 8.2.0 per gneyens; no plan to fix Defect ID 44810

• See interface tunnel.

tunnel checksum

• Use to enable checksum computation across a GRE tunnel.
• Checksum computation is not supported for DVMRP tunnels.
• Selecting this feature causes the E-series router to drop corrupted packets it receives on the tunnel interface.
• Example

  host1(config)#interface tunnel gre:tunnel2

  host1(config-if)#tunnel checksum

• Use the no version to disable the checksum option.
• See tunnel checksum.

tunnel destination

• Use to configure the remote end of the tunnel.
• Specify either the IP address of an interface on the remote router or the hostname of the remote router.
  • The IP address is the address for the destination interface.
  • The hostname is the name of the destination interface.
• Example 1

  host1(config)#interface tunnel dvmrp:tunnel2

  host1(config-if)#tunnel destination 192.13.7.1

• Example 2

  host1(config)#interface tunnel dvmrp:tunnel2

  host1(config-if)#tunnel destination remoteHost

• Use the no version to remove the destination of a tunnel.
• See tunnel destination.

tunnel mtu

• Use to set the MTU for the tunnel.
• Specify a value in the range 1024–10240 bytes.
• Example

  host1(config-if)#tunnel mtu 7500

• Use the no version to restore the default, 10240 bytes.
• See tunnel mtu.

tunnel source

• Use to configure the source of the tunnel.
• Specify either the primary IP address or the type and specifier of an interface.
• Do not specify an unnumbered interface.
• Example 1—Primary IP address

  host1(config)#interface tunnel dvmrp:boston-tunnel-1

  host1(config-if)#tunnel source 192.10.2.1

• Example 2—ATM interface on an ERX-7xx model, ERX-14xx model, or the ERX-310 router that uses the slot/port format

  host1(config)#interface tunnel dvmrp:boston-tunnel-1

  host1(config-if)#tunnel source atm 5/0.12

• Example 3—ATM interface on an E320 router that uses the slot/adapter/port format

  host1(config)#interface tunnel dvmrp:boston-tunnel-1

  host1(config-if)#tunnel source atm 5/1/0.12

• Use the no version to remove the source of a tunnel.
• See tunnel source.

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