430
Appendix C
Route Summarization
CIDR Block. This does mean that all those network numbers must be well
planned, and they must reside only out Serial 0 on RouterA in Figure C.1.
F I G U R E C . 1
Summarizing Routes EIGRP
Let's take a look at an example of using the ip summary-address eigrp
command:
Cisco3640(config)#interface serial 0
Cisco3640(config-if)#ip address 172.16.16.254
255.255.255.0
Cisco3640(config-if)#ip summary-address eigrp 10
172.16.0.0 255.255.240.0
Cisco3640(config-if)#bandwidth 64
Cisco3640(config-if)#no shut
Route Summarization for BGP
W
e employ route summarization with BGP to limit the number of
routes in the routing table by using the aggregate-address command in
the BGP router configuration mode. This command creates an atomic aggre-
gate, or summarized, entry in the BGP table. The syntax summary-only tells
BGP to advertise only the summary and not the specific routes to each des-
tination. You can use the as-set syntax to include a list of all of the AS numbers
172.16.5.0/22
172.16.16.0/30
S0
S0
172.16.24.0/30
172.16.20.0/30
RouterC
RouterD
RouterB
RouterA
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