Configuring FEC Deaggregation
When an LDP egress router 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.
By default, because an LSP cannot be split across multiple next hops and all the prefixes are bound into a single LSP, you cannot load-balance across equal-cost paths.
To change the default to load-balance across equal-cost paths, you need to 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.
