• IGP metric to BGP next hop
Route maps
Route maps must be applied to IPv6 unicast address prexes in IPv6 address family conguration mode.
By default, route maps that are applied under IPv4 address family conguration mode using the neighbor route-map command are
applied to only IPv4 unicast address prexes. To apply route maps to IPv6 unicast address prexes, the neighbor route-map command
must be used in IPv6 address family conguration mode. The route maps are applied as the inbound or outbound routing policy for
neighbors under the specied address family. Conguring separate route maps under each address family type simplies managing
complicated or dierent policies for each address family.
BGP4+ outbound route
ltering
The BGP4+ Outbound Route Filtering Capability (ORF) feature is used to minimize the number of BGP updates sent between BGP
peers.
When the ORF feature is enabled, unwanted routing updates are ltered out, reducing the amount of system resources required for
generating and processing routing updates. The ORF feature is enabled through the advertisement of ORF capabilities to peer routers.
The locally
congured BGP4+ inbound prex lters are sent to the remote peer so that the remote peer applies the lter as an outbound
lter for the neighbor.
The ORF feature can be congured with send and receive ORF capabilities. The local peer advertises the ORF capability in send mode,
indicating that it will accept a prex list from a neighbor and apply the prex list to locally congured ORFs. The local peer exchanges the
ORF capability in send mode with a remote peer for a prex list that is congured as an inbound lter for that peer locally. The remote
peer only sends the rst update once it receives a ROUTEREFRESH request or BGP ORF with IMMEDIATE from the peer. The local
and remote peers exchange updates to maintain the ORF on each router.
BGP4+ confederations
A large autonomous system (AS) can be divided into multiple subautonomous systems and grouped into a single BGP4+ confederation.
Each subautonomous system must be uniquely identied within the confederation AS by a subautonomous system number. Within each
subautonomous system, all the rules of internal BGP (IBGP) apply. For example, all BGP routers inside the subautonomous system must
be fully meshed. Although EBGP is used between subautonomous systems, the subautonomous systems within the confederation
exchange routing information like IBGP peers. Next hop, Multi Exit Discriminator (MED), and local preference information is preserved
when crossing subautonomous system boundaries. To the outside world, a confederation looks like a single AS.
The AS path list is a loop-avoidance mechanism used to detect routing updates leaving one subautonomous system and attempting to
re-enter the same subautonomous system. A routing update attempting to re-enter a subautonomous system it originated from is
detected because the subautonomous system sees its own subautonomous system number listed in the update's AS path.
Route maps
FastIron Ethernet Switch Layer 3 Routing
482 53-1003627-04
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