4.3 Unregistering a Name

When a PNRP ID is unregistered, a Revoke CPA is sent to two entries from the Leaf Set of the ID being unregistered. One entry is the numerically closest ID greater than the local ID and the other entry is the numerically closest ID less than the local ID. Each recipient checks its cache to see if an entry exists for the PNRP ID. If one is found, the recipient removes it from its cache. If the entry was in a Leaf Set of a locally registered ID, the node FLOODs the Revoke CPA on to other members of its Leaf Set.

PNRP name revocation process

Figure 6: PNRP name revocation process

  1. The unregistering node (Node 6) creates a Revoke CPA for the Peer Name. The R field of the CPA is set to indicate that this is a Revoke CPA. It puts the Revoke CPA in a FLOOD message and sends it to the node in its Leaf Set with the numerically closest registered PNRP ID lower than its own (for example, Node 5). Upon receiving the FLOOD message, Node 5 removes the PNRP ID of the unregistering node from its local cache. If Node 5 has the PNRP ID of the unregistering node in its Leaf Set, it forwards the Revoke CPA to the node in its Leaf Set with the closest registered PNRP ID lower than its own (for example, Node 4), where it is processed exactly as described here. This continues until the Revoke CPA reaches a node that does not have the PNRP ID of the unregistering node in either its cache or its Leaf Set, at which point possessing (and forwarding) of the Revoke CPA ceases.

  2. Node 6 sends an identical FLOOD message to the node in its Leaf Set with the closest registered PNRP ID greater than its own (for example, Node 7). Node 7 processes the Revoke CPA exactly as described in step 1, except that all Revoke CPA forwards will be made to nodes with numerically greater PNRP IDs.

  3. The unregistration of Node 6 produces gaps in the Leaf Sets of its nearby nodes. Node 6 therefore sends a FLOOD message to the node in its Leaf Set with the smallest PNRP ID (for example, Node 1). The FLOOD message informs the recipient of the node with the next greater PNRP ID than the unregistering node (for example, Node 7). Node 1 will place the Node 7 PNRP ID in its Leaf Set where the Node 6 PNRP ID used to reside.

  4. Node 6 repeats step 3, notifying the node in its Leaf Set with the greatest PNRP ID (for example, Node 11) of the node with the next lower PNRP ID than the unregistering node (for example, Node 5), allowing Node 11 to repair its Leaf Set as well.

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