3Com S7906E Configuration Manual page 721

Figure 1-9 L1/L2 LSP format
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.
1-10
Figure 1-10, Router A