H3C LS-3100-52P-OVS-H3 Operation Manual page 620

PDU Length: Total length of the PDU in bytes.
Remaining Lifetime: LSP remaining lifetime in seconds.
LSP ID: Consists of the system ID, the pseudonode ID (one byte) and the LSP fragment number
(one byte).
Sequence Number: LSP sequence number.
Checksum: LSP checksum.
P (Partition Repair): Only for L2 LSPs. It indicates whether the router supports partition repair.
ATT (Attachment): Generated by a L1/L1 router for L1 LSPs only. It indicates that the router
generating the LSP is connected to multiple areas.
OL (LSDB Overload): Indicates that the LSDB is not complete because the router runs out of
memory. In this case, other routers will not send packets to the overloaded router, except packets
destined to the networks directly connected to the router. For example, in
forwards packets to Router C through Router B. Once other routers know the OL field of LSPs from
Router B is set to 1, Router A will send packets to Router C via Router D and Router E, but still
send to Router B packets destined to the network directly connected to Router B.
Figure 1-10 LSDB overload
IS Type: Type of the router generating the LSP.
SNP format
A sequence number PDU (SNP) acknowledges the latest received LSPs. It is similar to an
Acknowledge packet, but more efficient.
SNP involves Complete SNP (CSNP) and Partial SNP (PSNP), which are further divided into Level-1
CSNP, Level-2 CSNP, Level-1 PSNP and Level-2 PSNP.
CSNP covers the summary of all LSPs in the LSDB to synchronize the LSDB between neighboring
routers. On broadcast networks, CSNP is sent by the DIS periodically (10s by default). On point-to-point
networks, CSNP is only sent during the first adjacency establishment.
The CSNP packet format is shown in Figure 1-11.
1-10
Figure 1-10, Router A