Generic Commands
Page 274 7210 SAS M, T, X, R6, Mxp MPLS Configuration
Guide
aggregate-prefix-match
Syntax [no] aggregate-prefix-match
Context config>router>ldp
Description The command enables the use by LDP of the aggregate prefix match procedures.
When this option is enabled, LDP performs the following procedures for all prefixes. When an LSR
receives a FEC-label binding from an LDP neighbor for a given specific FEC1 element, it will install
the binding in the LDP FIB if:
• It is able to perform a successful longest IP match of the FEC prefix with an entry in the
routing table, and
• The advertising LDP neighbor is the next-hop to reach the FEC prefix.
When such a FEC-label binding has been installed in the LDP FIB, then LDP programs an NHLFE
entry in the egress data path to forward packets to FEC1. It also advertises a new FEC-label binding
for FEC1 to all its LDP neighbors.
When a new prefix appears in the routing table, LDP inspects the LDP FIB to determine if this prefix
is a better match (a more specific match) for any of the installed FEC elements. For any FEC for
which this is true, LDP may have to update the NHLFE entry for this FEC.
When a prefix is removed from the routing table, LDP inspects the LDP FIB for all FEC elements
which matched this prefix to determine if another match exists in the routing table. If so, it updates
the NHLFE entry accordingly. If not, it sends a label withdraw message to its LDP neighbors to
remove the binding.
When the next hop for a routing prefix changes, LDP updates the LDP FIB entry for the FEC
elements which matched this prefix. It also updates the NHLFE entry for these FEC elements
accordingly.
The no form of this command disables the use by LDP of the aggregate prefix procedures and deletes
the configuration. LDP resumes performing exact prefix match for FEC elements.
Default no aggregate-prefix-match
prefix-exclude
Syntax prefix-exclude policy-name [policy-name...(up to 5 max)]
no prefix-exclude
Context config>router>ldp>aggregate-prefix-match
Description This command specifies the policy name containing the prefixes to be excluded from the aggregate
prefix match procedures. In this case, LDP will perform an exact match of a specific FEC element
prefix as opposed to a longest match of one or more LDP FEC element prefixes, against this prefix
when it receives a FEC-label binding or when a change to this prefix occurs in the routing table.
The no form of this command removes all policies from the configuration.
Default no prefix-exclude.
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