![]() If a swap-label is not configured, the default value is 3.Ī route-table entry is required for a FEC with a pop operation to be advertised. Permitted operations are swap to originate a FEC for which the LSR is not egress or pop to originate a FEC for which the LSR is egress.įor a swap operation, an incoming label can be swapped with a label in the range of 16 to 1048575. This command adds a FEC to the LDP prefix database with a specific label operation on the node. LDP then only performs an exact prefix match for FEC elements. The no form of this command disables the use of the aggregate prefix match function. It also updates the NHLFE entry for the FEC elements. If the next hop for a routing prefix changes, LDP updates the LDP FIB entry for the FEC elements that matched this prefix. If another match does not exist, the LSR removes the FEC binding and sends a label withdraw message to its LDP neighbors. This may mean that the LSR used as the next hop will change if so, the NHLFE entry for that FEC must be changed. If another match exists, LDP must use it. When a prefix is removed from the RIB, LDP checks the LDP FIB for all FEC elements that matched this prefix to determine if another match exists in the routing table. If a closer match is found, this may mean that the LSR used as the next hop will change if so, the NHLFE entry for that FEC must be changed. When a new prefix appears in the RIB, LDP checks the LDP FIB to determine if this prefix is a closer match for any of the installed FEC elements. ![]() LDP also advertises a new FEC-label binding for FEC1 to all its LDP neighbors. When the FEC-label binding has been installed in the LDP FIB, LDP programs an NHLFE entry in the egress data path to forward packets to FEC1. The advertising LDP neighbor is the next hop to reach FEC1
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