Service Manual

Route Map Continue
The BGP route map continue feature, continue [sequence-number], (in ROUTE-MAP mode) allows movement from one
route-map entry to a specific route-map entry (the sequence number).
If you do not specify a sequence number, the continue feature moves to the next sequence number (also known as an “implied
continue”). If a match clause exists, the continue feature executes only after a successful match occurs. If there are no
successful matches, continue is ignored.
Match a Clause with a Continue Clause
The continue feature can exist without a match clause.
Without a match clause, the continue clause executes and jumps to the specified route-map entry. With a match clause and a
continue clause, the match clause executes first and the continue clause next in a specified route map entry. The continue
clause launches only after a successful match. The behavior is:
● A successful match with a continue clause—the route map executes the set clauses and then goes to the specified route
map entry after execution of the continue clause.
● If the next route map entry contains a continue clause, the route map executes the continue clause if a successful match
occurs.
● If the next route map entry does not contain a continue clause, the route map evaluates normally. If a match does not occur,
the route map does not continue and falls-through to the next sequence number, if one exists
Set a Clause with a Continue Clause
If the route-map entry contains sets with the continue clause, the set actions operation is performed first followed by the
continue clause jump to the specified route map entry.
● If a set actions operation occurs in the first route map entry and then the same set action occurs with a different value in a
subsequent route map entry, the last set of actions overrides the previous set of actions with the same set command.
● If the set community additive and set as-path prepend commands are configured, the communities and AS
numbers are prepended.
Configuring BGP Confederations
Another way to organize routers within an AS and reduce the mesh for IBGP peers is to configure BGP confederations.
As with route reflectors, BGP confederations are recommended only for IBGP peering involving many IBGP peering sessions per
router. Basically, when you configure BGP confederations, you break the AS into smaller sub-AS, and to those outside your
network, the confederations appear as one AS. Within the confederation sub-AS, the IBGP neighbors are fully meshed and the
MED, NEXT_HOP, and LOCAL_PREF attributes are maintained between confederations.
To configure BGP confederations, use the following commands.
● Specifies the confederation ID.
CONFIG-ROUTER-BGP mode
bgp confederation identifier as-number
○ as-number: from 0 to 65535 (2 Byte) or from 1 to 4294967295 (4 Byte).
● Specifies which confederation sub-AS are peers.
CONFIG-ROUTER-BGP mode
bgp confederation peers as-number [... as-number]
○ as-number: from 0 to 65535 (2 Byte) or from 1 to 4294967295 (4 Byte).
All Confederation routers must be either 4 Byte or 2 Byte. You cannot have a mix of router ASN support.
To view the configuration, use the show config command in CONFIGURATION ROUTER BGP mode.
Border Gateway Protocol (BGP)
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