debugs and verification
show run | section router eigrp
debug ip eigrp
router eigrp 1
network 192.168.3.0
network 10.0.0.0
distribute-list 1 out !
access-list 1 permit 192.168.3.160 0.0.0.15
Solution: Ensure that the distribute list allows the rang of network that needed to be advertised.
2. EIGRP Is Not Advertising Routes to Its Neighbors—Cause: Discontiguous Networks
another issue with EIGRP not advertising the network could be manual summarization configured on the interface or auto-summarization across a major network boundary
debugs and verification:
show run | section router eigrp
debug ip eirgrp
a. One is to configure the command no auto-summary under router eigrp. This command tells EIGRP not to autosummarize to major network boundaries.
b. to change the IP address of the serial interfaces on each side of the link and use different IP that is different with existing.
3. EIGRP Is Not Advertising Routes to Neighbors—Cause: Split-Horizon Issues
EIGRP has its own split-horizon command. This command, configured under the inter-face,
debugs and verification:
show run | section router eigrp
debug ip eirgrp
Solution:
a. disabling Split horizon
interface serial 0
ip address 172.16.2.1 255.255.255.0
no IP split-horizon EIGRP 1 b. Another fix for the split-horizon problem is to configure subinterfaces on the hub router and assign different IP address subnets for each subinterface.
4. EIGRP advertises unexpected routes to its neighbors.
Router B# interface ethernet 0
ip address 192.168.130.1 255.255.255.0
interface serial 0
ip address 10.1.1.2 255.255.255.0
router eigrp 1 network 192 .168.130.0
network 10.0.0.0
ip route 192.168.1.0 255.255.255.0 ethernet 0
ip route 192.168 2.0 255.255.255.0 ethernet 0
ip route 192.168 3.0 255.255.255.0 ethernet 0
ip route 192.168 4.0 255.255.255.0 ethernet 0
.
.
.
ip route 192.168.127.0 255.255.255.0 ethernet 0
without inserting the redistribute static command under the router eigrp command in Router B, Router B automatically redistributes all the 127 static routes configured to Router A. This can cause unnecessary routes being advertised inadvertently throughout the entire network. The cause of the problem is that the static routes are configured with the outbound interface. In this case, the router thinks that all the static routes are directly connected to the Ethernet 0 interface. These Ethernet interfaces also are covered under the router EIGRP process by the network 192.168.130.0 command. Because Ethernet 0 is considered to run EIGRP, all the networks connected to it by a static route also are considered to belong to the EIGRP process. The router then advertises all these static routes even though redistribute static is not configured.
solution:
a. to configure a distribute list that prevents the router from advertising all those static routes
router eigrp 1
network 192.168.130.0
network 10.0.0.0
distribute-list 1 out
!
access-list 1 deny 192.168.0.0 0.0.127.255
access-list 1 permit any
b. or to change the static routes to reference the next-hop IP addresses instead of an interface. This way, the router will not advertise all these static routes and flood the entire network with unnecessary routes.
ip route 192.168.1.0 255.255.255.0 192.168.130.2
ip route 192.168.2.0 255.255.255.0 192.168.130.2
ip route 192.168.3.0 255.255.255.0 192.168.130.2
ip route 192.168.4.0 255.255.255.0 192.168.130.2
.
.
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ip route 192.168.127.0 255.255.255.0 192.168.130.2 5. EIGRP Is Advertising Routes with Unexpected Metric
advertise an unexpected metric to its neighbors. The EIGRP metric is the basis of route selection done by EIGRP, which selects the route with the lowest EIGRP metric to the destination network. An unexpected EIGRP metric being sent or received on the router might alter route selection to the destination network. The end result might be suboptimal routing.
debugs and verification:
show ip route x.x.x.x
show eigrp topology x.x.x.x y.y.y.y
Solution: Ensure there are no off-set list configured that changes the metrics of the outgoing interface.
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