# Remote Neighbors

You can create RIP remote neighbors to enable the router to establish neighbor adjacencies through unidirectional interfaces, such as MPLS tunnels, rather than the standard practice of using the same interface for receipt and transmission of RIP packets. The remote neighbor can be more than one hop away through intermediate routes that are not running RIP. RIP uses the interface associated with the best route to the remote neighbor to reach the neighbor. A best route to the neighbor must exist in the IP routing table.

You must explicitly configure remote neighbors on the RIP routers to specify the remote neighbor with which the router will form an adjacency and the source IP address the router will use for RIP packets destined to its peer remote neighbor.

To form an adjacency with its remote neighbor, the router sends all RIP packets to the remote neighbor as unicast packets with the destination IP address equal to the source IP address of the remote neighbor. The loopback interface associated with the source IP address for the remote neighbor acts as a logical RIP interface for the neighbor.

To prevent routing loops, you can disable split horizon and enable poison reverse routing updates.

The remote-neighbor command to specify the remote neighbors is mandatory. Configuration of all other remote-neighbor attributes is optional.

authentication-key

- Use to specify the password for text authentication and the key for MD5 authentication for RIP remote-neighbor interface.
- This command is supported only in RIPv2. Authentication is disabled by default.
- Example
  host1(config-router-rn)#authentication key 0 jun27ior
- Use the no version to clear the key for the remote-neighbor interface.
- See authentication-key

authentication mode

- Use to specify the authentication mode for the remote neighbor interface.
- Specify text to send a simple text password to remote neighbors. If a remote neighbor does not have the same password, requests and updates from this router are rejected.
- Specify md5 keyID to send an MD5 hash to remote neighbors. Remote neighbors must share the MD5 key to decrypt the message and encrypt the response.
- This command is supported only in RIPv2. Authentication is disabled by default.
- Example
  host1(config-router-rn)#authentication mode text
- Use the no version to remove authentication from the RIP remote-neighbor interface.
- See authentication mode

distribute-list

- Use to apply a specific access list to either incoming or outgoing RIP route updates on the RIP remote-neighbor interface.
- An IP access list acts as a filter. Refer to access-list in the JunosE Command Reference Guide for more information.
- Example
  host1(config)#distribute-list 5 in
- Use the no version to stop application of the distribute list.
- See distribute-list

exit-remote-neighbor

- Use to exit from the Remote Neighbor Configuration mode and return to Router Configuration mode.
- Example
  host1(config-router-rn)#exit-remote-neighbor
- There is no no version.
- See exit-remote-neighbor

receive version

- Use to restrict the RIP version that the router can receive on a RIP remote-neighbor interface. The default is to receive both RIPv1 and RIPv2.
- The off keyword overrides any other specified option; for example, configuring both 1 and off or both 2 and off has the same result as configuring only off.
- Example
  host1(config-router-rn)#receive version 1
- Use the no version to restore the default value, 1 2.
- See receive version

remote-neighbor

- Use to configure a RIP remote neighbor.
- Example
  host1(config-router)#remote-neighbor 10.25.100.14
- Use the no version to remove the remote neighbor and any attributes configured for the remote neighbor.
- See remote-neighbor

send version

- Use to restrict the RIP version that the router can send on an interface. The default is to send only RIPv1.
- Example
  host1(config-router-rn)#send version 1
- Use the no version to restore the default value, 1.
- See send version

split-horizon

- Use to configure the split horizon and poison reverse features for RIP remote neighbors.
- Split horizon is enabled by default; poison reverse routing updates are disabled by default.
- Poison reverse routing updates set the metric for routes originating on the interface to infinity, thus explicitly advertising that the network is not reachable. This helps to prevent routing loops.
- Example
  host1(config-router-rn)#no split-horizon
- Use the no version to disable the split horizon and enable poison reverse routing updates.
- See split-horizon

time-to-live

- Use to configure a hop count by setting the value of the time-to-live field used by packets sent to a RIP remote neighbor.
- Example
  host1(config-router-rn)#time-to-live 12
- Use the no version to restore the default value, 16.
- See time-to-live

update-source

- Use to specify the RIP interface whose local address is used as the source address for the RIP connection to a remote neighbor.
- The source address assigned to a remote neighbor must be unique. If you configure a RIP router to form neighbor adjacencies with two RIP remote neighbors, then the RIP router must have two unique local source IP addresses, one for each of its remote neighbors.
- Example
  host1(config-router-rn)#update-source atm 2/0.17
- Use the no version to delete the source address from the connection to the remote neighbor.
- See update-source