Title: DECbrouter90 configuration example of IP RFC 877/1356 over X.25

Product: DECbrouter90 V9.14 and V10.x

Keyword: 

Question: How do I configure the DECbrouter90 to route IP datagrams over X.25
          to another vendor's router?

Solution:

        The DBR90 supports both STATIC routes over X.25 (RFC 877/1356) and 
dynamic routing over X.25. Dynamic routing over X.25 is not defined in the RFCs
for RIP, BGP, EGP, or Int IS-IS. However, OSPF does contain instructions for 
implementing OSPF over non-broadcast multi-access networks, ie... X.25, Frame
Relay, or SMDS. The DECbrouter90 running Cisco IOS supports dynamic routing 
over these networks via a proprietary implementation which may not interoperate
with other vendor's implementations, including Digital's other router products.
Thus, static routes are typically utilized when running IP over X.25 between 
different vendor's routers.

        This is an example of configuring static routes (RFC 877/1356) for IP 
datagrams over X.25.


        IP subnet 15.135.3.0, mask 255.255.255.0
        ------------------------------------------------
                                |
                                | E0
        -------------------------------------------------               
        |interface Ethernet 0                           |
        |ip address 15.135.3.2 255.255.255.0            |
        |!                                              |
        |interface Serial 0                             |
        |ip address 15.135.2.2 255.255.255.0            |
        |!                                              |
        |!IP address of X.25 WAN, all routers connected |
        |!to must have the same subnet address and      |
        |!subnet mask.                                  |
        |!                                              |
        |encapsulation X25-DCE                          |
        |!                                              |
        |!If connected to another router via a leased   |
        |!line point-to-point, then one router must be  |
        |!a DTE and the other a DCE.                    |
        |!                                              |
        |x25 address 210987654321                       |
        |!                                              |
        |!A valid DTE address supplied by the PSDN or   |
        |!a made up address for point-to-point          |
        |!                                              |
        |x25 map IP 15.135.2.1 123456789012             |
        |!                                              |
        |!Map the IP address on the X.25 serial         |
        |!interface to the remote DTE address on that   |
        |!same interface. One map is required for every |
        |!remote router on the PSDN. By leaving the     |
        |!broadcast qualifier off of the map command, no|
        |!RIP routing information is exchanged.         |
        |!                                              |
        |router rip                                     |
        |network 15.0.0.0                               |
        |!                                              |
        |!Configure RIP for the Ethernet.               |
        |!                                              |
        |ip route 15.135.2.0 255.255.255.0 15.135.2.1   |
        |!                                              |
        |!Setup a static route between the IP address   |
        |!specified in the X25 MAP command and the IP   |
        |!networks/subnets available on the ethernet    |
        |!side of the remote router                     |
        |!                                              |       
        -------------------------------------------------
                             | S0
                             |
            Subnet 15.135.2.0, mask 255.255.255.0
                           CLOUD        
            Subnet 15.135.2.0, mask 255.255.255.0
                             |
                             | S0
        -------------------------------------------------               
        |interface Ethernet 0                           |
        |ip address 15.135.1.1 255.255.255.0            |
        |!                                              |
        |interface Serial 0                             |
        |ip address 15.135.2.1 255.255.255.0            |
        |!                                              |
        |!IP address of X.25 WAN, all routers connected |
        |!must have the same subnet address and         |
        |!subnet mask.                                  |
        |!                                              |
        |encapsulation X25                              |
        |!                                              |
        |!If connected to another router via a leased   |
        |!line point-to-point, then one router must be  |
        |!a DTE and the other a DCE.                    |
        |!                                              |
        |x25 address 123456789012                       |
        |!                                              |
        |!A valid DTE address supplied by the PSDN or   |
        |!a made up address for point-to-point          |
        |!                                              |
        |x25 map IP 15.135.2.2 210987654321             |
        |!                                              |
        |!Map the IP address on the X.25 serial         |
        |!interface to the remote DTE address on that   |
        |!same interface. One map is required for every |
        |!remote router on the PSDN. By leaving the     |
        |!broadcast qualifier off of the map command, no|
        |!RIP routing information is exchanged.         |
        |!                                              |
        |router rip                                     |
        |network 15.0.0.0                               |
        |!                                              |
        |!Configure RIP for the Ethernet.               |
        |!                                              |
        |ip route 15.135.3.0 255.255.255.0 15.135.2.2   |
        |!                                              |
        |!Setup a static route between the IP address   |
        |!specified in the X25 MAP command and the IP   |
        |!networks/subnets available on the ethernet    |
        |!side of the remote router                     |
        |!                                              |       
        -------------------------------------------------
                                | E0
                                |
        -------------------------------------------------
        IP subnet 15.135.1.0, mask 255.255.255.0