On a P2P IS-IS network, after a neighbor relationship is established between R1 and R2,...

Explanation of IS-IS Packet Types and Synchronization Process:

In the given scenario, R2 requests LSPs from R1 to synchronize its Link State Database (LSDB). The following IS-IS packet types are involved in this synchronization process:

1. P2P IIH (Point-to-Point IS-IS Hello):

Purpose: Establishes and maintains IS-IS neighbor relationships.

Step: This packet is exchanged initially to detect and maintain the adjacency between R1 and R2.

2. PSNP (Partial Sequence Number PDU):

Purpose: Requests missing or outdated LSPs (Link State PDUs) from a neighbor to synchronize the LSDB.

Step: In this case, R2 sends a PSNP to R1 to request the missing or outdated LSP.

3. LSP (Link State PDU):

Purpose: Contains routing information and is used to update the LSDB.

Step: R1 sends the requested LSPs to R2 for synchronization.

4. CSNP (Complete Sequence Number PDU):

Purpose: Lists all LSPs in the sender ' s LSDB to help neighbors verify and request missing LSPs.

Step: R1 sends a CSNP during retransmission timeout to notify R2 of its LSPs.