Border Nodes

A border node is a network node that resides on the border of two Advanced Peer-to-Peer Networking subnetworks. Border nodes enable Advanced Peer-to-Peer Networking subnetworks to connect and yet remain distinct at the same time. Border nodes support session establishment and directory services across the boundaries of the subnetwork, but do not exchange topology information across the border. Session endpoints can be located in adjacent subnetworks having peripheral border nodes or nonadjacent subnetworks having extended border nodes. Figure 1 shows a peripheral border node.

In Figure 1, peripheral border node BN1 portrays itself as a network node to other network nodes within subnetwork A (its native network); however, to NN15 within subnetwork B, BN1 is viewed as an end node. The border node receives topology database update messages only from network nodes within its native subnetwork, although the border node is capable of establishing a session between the two subnetworks. When connecting to a node in a non-native subnetwork, the border node must either connect to an NN or another border node.

The extended border node is similar in function to the peripheral border node, but extends the session routing capability across nonadjacent subnetworks. The extended border node also provides the capability to partition a subnetwork into clusters; each cluster has its own network topology database, yet all have the same network identifier.