ISIS does not send CSNP packets under the P2P network type during the neighbor establishment process.

On point-to-point (P2P) IS-IS links, each router transmits a Complete Sequence Numbers PDU (CSNP) once, immediately after the adjacency reaches the UP state, to ensure database synchronization. Hence CSNP packets are indeed sent during neighbor establishment, making the statement false. Why Incorrect Option is Wrong: The only alternative to “False” is “True”. Because CSNPs are sent on P2P links at adjacency bring-up, the statement cannot be true.

1. Huawei, “S-Series Switches Configuration Guide – IS-IS,” V200R019C00, section “CSNP Transmission Rules”, p. 95 (“On point-to-point links, after an adjacency is established, each end sends one CSNP to start database synchronization.”).

2. ISO/IEC 10589:2002, clause 7.3.15 (“On point-to-point circuits, a CSNP shall be transmitted at adjacency establishment.”).