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3.7 Router-ID Anchoring Example OSPF Pseudonode

3.7. Router-ID Anchoring Example: OSPF Pseudonode​

Encoding of a broadcast LAN in OSPF provides a good example of how

Router-IDs and local Interface IPs are encoded. Consider Figure 32.

This represents a Broadcast LAN between a pair of routers. The

"real" (non-pseudonode) routers have both an IPv4 Router-ID and an

Area Identifier. The pseudonode does have an IPv4 Router-ID, an IPv4

Interface Address (for disambiguation), and an OSPF Area. Node1 is

the DR for the LAN; hence, its local IP address 10.1.1.1 is used as

both the Router-ID and Interface IP for the pseudonode keys. Two

unidirectional links, (Node1, Pseudonode1) and (Pseudonode1, Node2),

are being generated.

The Link NLRI of (Node1, Pseudonode1) is encoded as follows:

  • Local Node Descriptor

  • Remote Node Descriptor

The Link NLRI of (Pseudonode1, Node2) is encoded as follows:

  • Local Node Descriptor

  • Remote Node Descriptor

     +-----------------+    +-----------------+    +-----------------+
     |      Node1      |    |   Pseudonode1   |    |      Node2      |
     |   11.11.11.11   |--->|   11.11.11.11   |--->|  33.33.33.34    |
     |                 |    |     10.1.1.1    |    |                 |
     |      Area 0     |    |      Area 0     |    |      Area 0     |
     +-----------------+    +-----------------+    +-----------------+

                        Figure 32: OSPF Pseudonodes
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