Default Routing with EIGRP
A default route can be injected into EIGRP in two primary ways:
• Redistribute a default static route into EIGRP so that EIGRP recognizes the route of 0.0.0.0 to be the default route. A default static route is created with the global router entry ip route 0.0.0.0 0.0.0.0 next_hop_IP_address. This route then must be redistributed into EiGrp with the redistribute static command. If the network 0.0.0.0 is not used, you can still mark the route as a default route by using the ip default-network a.b.c.d command.
• Summarize a default route of 0.0.0.0 with the interface command ip summary-address eigrp as_number 0.0.0.0 0.0.0.0. The example in the previous section demonstrated how to propagate a default route with this command.
With both ways, the router needs the ip classless global command enabled. With IP classless, the router forwards any packets toward the default route that it does not have a more specific route toward. ip classless is enabled by default in Cisco IOS Software Release 12.0 and later.
In Figure 11-11, the canada_1 router advertises a default route to usa_1 and mexico_1. canada_1 does this by creating a static route pointing at a next-hop address of 172.16.3.3 or the canada_2 router.
Figure 11-11. EIGRP Default Routing
Figure 11-11. EIGRP Default Routing
Example 11-27 lists the configuration of the canada_1 router advertising a default static route. Example 11-27 Advertising a Default Static Route with EIGRP on canada_1
router eigrp 2001
redistribute static network 172.16.0.0
redistribute the static routes default-metric 16000 630 254 1 1500
Don't forget the default-metric no auto-summary
ip classless ip route 0.0.0.0 0.0.0.0 172.16.3.3 " |he default route points at Canada_l router
IP classless must be enabled for default routing
Example 11-28 lists the route table of the mexico_1 router demonstrating how the default route is received. Notice that when the route is advertised, it is an external router because it is redistributed, and it has the * denoting it is the default route. The gateway of last resort also is set.
Example 11-28 Route Table of the mexico_1 Router mexico 1#show ip route
Codes: C - connected, S - static, I - IGRP, 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, E - EGP i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, * - candidate default U - per-user static route, o - ODR T - traffic engineered route
Gateway of last resort is 172.16.1.1 to network 0.0.0.0
172.16.0.0/24 is subnetted, 5 subnets C 172.16.5.0 is directly connected, Ethernet0
D 172.16.6.0 [90/2707456] via 172.16.1.1, 00:04:15, Serial0.1
C 172.16.1.0 is directly connected, Serial0.1
D 172.16.2.0 [90/2681856] via 172.16.1.1, 00:04:51, Serial0.1
D 172.16.3.0 [90/2185984] via 172.16.1.1, 00:04:51, Serial0.1
D 192.168.4.0/24 [90/2835456] via 172.16.1.1, 00:04:15, Serial0.1
10.0.0.0/8 is variably subnetted, 2 subnets, 2 masks D 10.1.2.0/30 [90/2313984] via 172.16.1.1, 00:04:51, Serial0.1
D 10.1.1.0/24 [90/2313984] via 172.16.1.1, 00:04:52, Serial0.1
182.16.0.0/24 is subnetted, 2 subnets D 182.16.4.0 [90/2313984] via 172.16.1.1, 00:04:52, Serial0.1
D 182.16.3.0 [90/2313984] via 172.16.1.1, 00:04:52, Serial0.1
D 192.168.3.0/24 [90/2835456] via 172.16.1.1, 00:04:15, Serial0.1
D*EX 0.0.0.0/0 [170/2331136] via 172.16.1.1, 00:00:53, Serial0.1 mexico 1#
Continue reading here: EIGRP Stub Routing
Was this article helpful?