Three methods of injecting default route into eigrp area
The first method:
redistribution
Steps: Write a default route on the border router R0 and apply the redistribute command.
R0#
interface Serial1/0
ipaddress 13.1.1.1 255.255.255.0
interface Serial1/3
ipaddress 12.1.1.2 255.255.255.0
router eigrp 90
redistribute static
network 13.1.1.0 0.0.0.255
noauto-summary
iproute 0.0.0.0 0.0.0.0 Serial1/3
R3#
interface Serial1/3
ipaddress 12.1.1.1 255.255.255.0
R1#
interface Serial1/0
ipaddress 13.1.1.2 255.255.255.0
interface Serial1/2
ipaddress 35.1.1.1 255.255.255.0
router eigrp 90
network 13.1.1.0 0.0.0.255
network 35.1.1.0 0.0.0.255
noauto-summary
R2#
interface Serial1/2
ipaddress 35.1.1.2 255.255.255.0
router eigrp 90
network 35.1.1.0 0.0.0.255
noauto-summary
R0 routing table has "S* 0.0.0.0/0 is directly connected, Serial1/3 " and learned "35 segments" and "directly connected 12 segments".
Thus, after republishing, other routers such as R1 and R2 have routing tables containing "D*EX 0.0.0.0/0 [170/3193856]via 35.1.1.1, 00:00:15, Serial1/2" and learned "13" and "35 segments."
C 12.1.1.0 is directly connected,Serial1/3
Note:R3 must have a backhaul ip route 0.0.0.0 0.0.0 s1/3, so that R2 can ping R3 .
The second method:
Network
Step: Border router R0 writes a default route, and then uses network to announce this default route to eigrp.
Only the R0 configuration differs from the previous method.
network0.0.0.0
iproute 0.0.0.0 0.0.0.0 Serial1/3
All other routers, including R0, R1 and R2, will learn the 12, 13 and 35 networks, as well as the internal eigrp default route. D* 0.0.0.0/0 [90/2681856] via 13.1.1.1, 00:01:56,Serial1/0
Note:R3 must have a backhaul ip route 0.0.0.0 0.0.0 s1/3, so that R2 can ping R3 .
The third method:
Ipdefault-network
Step: R0 configure ip default-network12.0.0.0(classful), network 12.0.0.0, ip route12.0.0.0 255.0.0.0 null 0. The third rule is to ensure that the local route has the route entry (12.0.0.0) just announced.
The routing table is as follows
R0 S* 12.0.0.0/8 is directly connected, Null0
R1 and R2 have similar routing tables.
Test on R0, open debug ip packet, ping ping 12.2.2.2
You'll see ping 12.2.2.2 exits s1/0.
*Apr 23 23:54:50.451: IP: tableid=0,s=12.1.1.2 (local), d=12.2.2.2 (Serial1/3), routed via RIB
Or ping 12.7.7.7 on R5 will find NNNNN instead of...。
If you don't add ip route 12.0.0.0255.0.0.0 null 0, then R5ping12.4.4.4 is...
