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Summarization is configurable on a per-interface basis in any router within a network.
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When summarization is configured on an interface, the router immediately creates a route pointing to null0.
–Loop-prevention mechanism
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When the last specific route of the summary goes away, the summary is deleted.
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The minimum metric of the specific routes is used as the metric of the summary route.
Configuring Manual Route Summarization
(config-if)#
ip summary-address eigrp as-number address mask [admin-distance]
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Creates a summary address that this interface will generate
基本网络配置
R1# interface Loopback0 ip address 172.16.1.1 255.255.255.0 interface FastEthernet0/0 ip address 10.1.1.1 255.255.255.0 router eigrp 100 network 10.1.1.1 0.0.0.0 network 172.16.1.1 0.0.0.0
R2# interface Loopback0 ip address 172.16.2.1 255.255.255.0 interface FastEthernet0/0 ip address 10.1.1.2 255.255.255.0 router eigrp 100 network 10.1.1.2 0.0.0.0 network 172.16.2.1 0.0.0.0
R3# interface Loopback0 ip address 172.16.3.1 255.255.255.0 interface FastEthernet0/0 ip address 202.100.1.3 255.255.255.0 interface FastEthernet1/0 ip address 10.1.1.3 255.255.255.0 router eigrp 100 network 10.1.1.3 0.0.0.0 network 172.16.3.1 0.0.0.0 network 202.100.1.3 0.0.0.0
#R4# interface FastEthernet0/0 ip address 202.100.1.4 255.255.255.0 router eigrp 100 network 202.100.1.4 0.0.0.0
Configuring Manual Route Summarization配置
R3# interface FastEthernet0/0 ip address 202.100.1.3 255.255.255.0ip summary-address eigrp 100 172.16.0.0 255.255.0.0
验证
R3#show ip route
Codes: L - local, C - connected, S - static, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2
i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
ia - IS-IS inter area, * - candidate default, U - per-user static route
o - ODR, P - periodic downloaded static route, H - NHRP, l - LISP
+ - replicated route, % - next hop override
Gateway of last resort is not set
10.0.0.0/8 is variably subnetted, 2 subnets, 2 masks
C 10.1.1.0/24 is directly connected, FastEthernet1/0
L 10.1.1.3/32 is directly connected, FastEthernet1/0
172.16.0.0/16 is variably subnetted, 5 subnets, 3 masks
D 172.16.0.0/16 is a summary, 00:00:11, Null0
D 172.16.1.0/24 [90/156160] via 10.1.1.1, 00:08:59, FastEthernet1/0
D 172.16.2.0/24 [90/156160] via 10.1.1.2, 00:08:59, FastEthernet1/0
C 172.16.3.0/24 is directly connected, Loopback0
L 172.16.3.1/32 is directly connected, Loopback0
202.100.1.0/24 is variably subnetted, 2 subnets, 2 masks
C 202.100.1.0/24 is directly connected, FastEthernet0/0
L 202.100.1.3/32 is directly connected, FastEthernet0/0
R4#show ip route
Codes: L - local, C - connected, S - static, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2
i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
ia - IS-IS inter area, * - candidate default, U - per-user static route
o - ODR, P - periodic downloaded static route, H - NHRP, l - LISP
+ - replicated route, % - next hop override
Gateway of last resort is not set
10.0.0.0/24 is subnetted, 1 subnets
D 10.1.1.0 [90/30720] via 202.100.1.3, 00:09:41, FastEthernet0/0
D 172.16.0.0/16 [90/156160] via 202.100.1.3, 00:02:03, FastEthernet0/0
202.100.1.0/24 is variably subnetted, 2 subnets, 2 masks C 202.100.1.0/24 is directly connected, FastEthernet0/0 L 202.100.1.4/32 is directly connected, FastEthernet0/0