Administrator Guide

Layer 3 Routing Commands 1248
• summary-only – When specified, the more-specific routes within the
aggregate address are not advertised to neighbors.
Default Configuration
No aggregate addresses are configured by default. Unless the options are
specified, the aggregate is advertised with the ATOMIC_AGGREGATE
attribute and an empty AS path, and the more specific routes are advertised
along with the aggregate.
Command Mode
• BGP Router Configuration mode
• IPv6 Address Family Configuration mode
User Guidelines
To be considered a match for an aggregate address, a prefix must be more
specific (i.e., have a longer prefix length) than the aggregate address. A prefix
whose prefix length equals the length of the aggregate address is not
considered a match.
When BGP originates a summary address, it installs a reject route in the
common routing table for the summary prefix. Any received packets that
match the summary prefix but not a more specific route match the reject
route and are dropped.
BGP accepts up to 128 summary addresses for each address family.
Command History
Introduced in version 6.2.0.1 firmware.
Example
console(config-router)#aggregate-address 10.27.21.0 255.255.255.0
bgp aggregate-different-meds (BGP Router
Configuration)
Use the bgp aggregate-different-meds command to control the aggregation of
routes with different multi-exit discriminator (MED) attributes. By default,
BGP only aggregates routes that have the same MED value.