HP VPN Firewall Appliances Appendix Protocol Reference

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Figure 18 L1/L2 LSP format
Major fields of the L1/L2 LSP are as follows:
• 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)—Partition bit that is only for L2 LSPs. This field indicates whether the router supports
partition repair.
• ATT (Attach)—Attach bit that is generated by a L1/L1 router for L1 LSPs only. This field indicates that
the router generating the LSP is connected to multiple areas.
• OL (Overload)—Indicates that the LSDB is not complete because the router has run out of memory.
Other routers will not send packets to the overloaded router, except packets destined to the
networks directly connected to the router. For example, in Figure 19,
Router A forwards packets to
Router C through Ro
uter 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.
• IS type—Type of the router generating the LSP.