Configuration Example

In this example, two GRE tunnel interfaces are configured on different virtual routers of an E-series router. The source of the first tunnel interface matches the destination of the second tunnel interface and vice versa.

Note: This example contains an ATM interface configuration for an ERX-7xx model, ERX-14xx model, or ERX-310 router that uses the slot/port format.

1. Configure a virtual router called boston that supports one end of the tunnel.

   host1#virtual-router boston

2. Configure a physical or loopback interface for the end of the tunnel on virtual router boston.

   The IP address of this interface appears in the header of tunneled frames and is used for forwarding traffic.

   host1:boston#interface atm 12/0.5

   host1:boston(config-if)#ip address 10.5.5.5 255.255.255.0

3. Configure the tunnel interface on virtual router boston.
   1. Create the tunnel interface.

      host1:boston(config)#interface tunnel gre:ChicagoTunnel

   2. Configure the source and destination points of the tunnel interface.

      host1:boston(config-if)#tunnel source 10.5.5.5

      host1:boston(config-if)#tunnel destination 10.6.6.6

   3. Set the MTU for the tunnel.

      host1:boston(config-if)#tunnel mtu 8000

   4. Configure the IP address of the tunnel interface.

      host1:boston(config-if)#ip address 10.7.7.7 255.255.255.0

4. Configure a virtual router called chicago that supports the other end of the tunnel.

   host1(config)#virtual-router chicago

5. Configure a physical or loopback interface for the end of the tunnel on virtual router chicago.

   host1:chicago(config)#interface atm 12/1.5

   host1:chicago(config-if)#ip address 10.6.6.6 255.255.255.0

6. Configure the tunnel interface on virtual router chicago.
   1. Create the tunnel interface.

      The name of the tunnel interface can differ from the tunnel interface configured in Step 3.

      host1:chicago(config-if)#interface tunnel gre:BostonTunnel

   2. Configure the source and destination points of the tunnel interface.

      The destination of this tunnel interface matches the source of the tunnel interface configured in Step 3 and vice versa.

      host1:chicago(config-if)#tunnel source 10.6.6.6

      host1:chicago(config-if)#tunnel destination 10.5.5.5

   3. Set the MTU for the tunnel.

      The MTU must match the MTU configured in Step 3.

      host1:chicago(config-if)#tunnel mtu 8000

   4. Configure the IP address of the tunnel interface.

      host1:chicago(config-if)#ip address 10.9.9.9 255.255.255.0

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