Global LDP Filters
Page 528 7450 ESS MPLS Guide
Inbound filtering is performed by way of the configuration of an import policy to control the label
bindings an LSR accepts from its peers. Label bindings can be filtered based on:
• Prefix-list: Match on bindings with the specified prefix/prefixes.
The default import policy is to accept all FECs received from peers.
Outbound filtering is performed by way of the configuration of an export policy. The Global LDP
export policy can be used to explicitly originate label bindings for local interfaces. The Global
LDP export policy does not filter out or stop propagation of any FEC received from neighbors.
Use the LDP peer export prefix policy for this purpose. It must also be noted that the system IP
address AND static FECs cannot be blocked using an export policy.
Export policy enables configuration of a policy to advertise label bindings based on:
• Direct: All local subnets.
• Prefix-list: Match on bindings with the specified prefix or prefixes.
The default export policy is to originate label bindings for system address only and to propagate all
FECs received from other LDP peers.
Finally, it must be noted that the 'neighbor' statement inside a global import or export policy is not
considered by LDP. Use the LDP peer import or export prefix policy for this purpose.
Per LDP Peer FEC Import and Export Policies
The FEC prefix export policy provides a way to control which FEC prefixes received from
prefixes received from other LDP and T-LDP peers are re-distributed to this LDP peer.
The user configures the FEC prefix export policy using the following command:
config>router>ldp>session-parameters>peer>export-prefixes policy-name
By default, all FEC prefixes are exported to this peer.
The FEC prefix import policy provides a mean of controlling which FEC prefixes received from
this LDP peer are imported and installed by LDP on this node. If resolved these FEC prefixes are
then re-distributed to other LDP and T-LDP peers.
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