ECS4660-28F_Management Guide-R03

C HAPTER 51 | IP Routing Commands
Border Gateway Protocol (BGPv4)
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COMMAND USAGE
◆ Using this command without any keywords will create an aggregate
entry in the routing table if any more specific routes are available in the
specified range. The aggregate route does not include any individual
route attributes (e.g., AS-Path or Community). It is advertised as
coming from this autonomous system and has the atomic aggregate
attribute set to indicate that some information may be missing.
◆ Using the as-set keyword creates an aggregate route where the
advertised path is an AS-Set that consists of all elements contained in
all of paths being summarized. AS-Set information can be used to avoid
routing loops because it records where the route has been. If a router
notes its own AS number in the AS-Set of the aggregate update, it will
drop the aggregate to prevents loop. However, when aggregating tens
or hundreds of routes, avoid advertising routing information in this
manner, since this route may be frequently withdrawn and updated as
AS path reachability information for the summarized routes changes.
◆ Using the summary-only keyword creates the aggregate route, while
at the same time suppressing advertisements of more specific routes to
all neighbors.
EXAMPLE
Console(config-router)#aggregate-address 100.1.0.0 255.255.0.0 summary-only
Console(config-router)#aggregate-address 100.2.0.0 255.255.0.0 summary-only
as-set
Console(config-router)#aggregate-address 100.3.0.0 255.255.0.0 as-set
Console(config-router)#end
Console#show ip bgp
BGP table version is 0, local router ID is 192.168.0.4
Status codes: s suppressed, d damped, h history, * valid, > best, i -
internal,
r RIB-failure, S Stale, R Removed
Origin codes: i - IGP, e - EGP, ? - incomplete
Network Next Hop Metric LocPrf Weight Path
*>i192.168.0.0/24 0.0.0.0 0 32768 i
bgp client-to-client
reflection
This command restores route reflection via this router. Use the no form to
disable route reflection.
SYNTAX
[no] bgp client-to-client reflection
COMMAND MODE
Router Configuration
DEFAULT SETTING
Enabled