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Configuring FEC Deaggregation

When an LDP egress router or switch advertises multiple prefixes, the prefixes are bound to a single label and aggregated into a single forwarding equivalence class (FEC). By default, LDP maintains this aggregation as the advertisement traverses the network.

Normally, because an LSP is not split across multiple next hops and the prefixes are bound into a single LSP, load-balancing across equal-cost paths does not occur. You can, however, load-balance across equal-cost paths if you configure a load-balancing policy and deaggregate the FECs.

Deaggregating the FECs causes each prefix to be bound to a separate label and become a separate LSP.

To configure deaggregated FECs, include the deaggregate statement:

For a list of hierarchy levels at which you can include this statement, see the statement summary section for this statement.

For all LDP sessions, you can configure deaggregated FECs only globally.

Deaggregating a FEC allows the resulting multiple LSPs to be distributed across multiple equal-cost paths and distributes LSPs across the multiple next hops on the egress segments but installs only one next hop per LSP.

To aggregate FECs, include the no-deaggregate statement:

For a list of hierarchy levels at which you can include this statement, see the statement summary section for this statement.

For all LDP sessions, you can configure aggregated FECs only globally.

Published: 2013-04-03