ISIS-SPB control packets
ISIS-SPB control packets include hello, LSP, and SNP. All SPBM control packets are encapsulated in 802.1q.
Hello
SPBM neighbors send IS-IS hello (IIH) PDUs to establish and maintain adjacencies.
LSP
Adjacent SPBM neighbors send link state PDUs (LSPs) to advertise topology data.
SNP
Adjacent SPBM neighbors exchange sequence number PDUs (SNPs) for LSDB synchronization.
SNPs include complete SNP (CSNP) and partial SNP (PSNP).
CSNP—Contains the digest of each LSP in the LSDB. Adjacent routers exchange CSNPs to maintain LSDB synchronization.
PSNP—Contains the sequence numbers of recently received LSPs. An SPBM node uses a PSNP to acknowledge LSPs or to request needed LSPs from a neighbor.