EIGRP neighbor establishment problem

[Roger Base]

HI. 

I have two switches that where I want to create eigrp neighbor establisment between them. But for some reason nothing happens when I try. No eigrp neighbor establishment is up. What is the reason ?

(EIGRP IS OK between R1 and SW1. But not between SW1 and SW5) VLAN24 Layer 3 interface is on R1. Both the SW1 and SW5 needs to have VLAN24 route to R1 trough the EIGRP. 

Toplogy:

R1<-VLAN19->SW1<- VLAN24-->SW5

SW1 config:

router eigrp 111
 network 136.1.0.0
 network 150.1.9.0 0.0.0.255
 network 172.16.3.0 0.0.0.255

SW1#show ip int bri
Interface              IP-Address      OK? Method Status                Protocol
Vlan1                  unassigned      YES manual administratively down down    
Vlan17                 136.1.17.9      YES manual up                    up      
Vlan19                 136.1.19.9      YES manual up                    up      
Vlan24                 136.16.3.200    YES manual up                    up      
Vlan27                 136.1.27.9      YES manual up                    up      
Vlan29                 136.1.29.9      YES manual up                    up      
Vlan47                 136.1.47.9      YES manual up                    up      

SW1#show ip route

     136.1.0.0/24 is subnetted, 6 subnets
C       136.1.27.0 is directly connected, Vlan27
C       136.1.29.0 is directly connected, Vlan29
C       136.1.17.0 is directly connected, Vlan17
C       136.1.19.0 is directly connected, Vlan19
C       136.1.47.0 is directly connected, Vlan47
D       136.1.37.0 [90/3072] via 136.1.17.17, 05:25:28, Vlan17
     136.16.0.0/24 is subnetted, 1 subnets
C       136.16.3.0 is directly connected, Vlan24
     172.16.0.0/24 is subnetted, 3 subnets
D       172.16.10.0 [90/26112] via 136.1.19.1, 05:25:28, Vlan19
D       172.16.1.0 [90/26112] via 136.1.19.1, 05:25:28, Vlan19
D       172.16.3.0 [90/26112] via 136.1.19.1, 00:52:15, Vlan19 -- **R1
     150.1.0.0/32 is subnetted, 4 subnets
C       150.1.9.9 is directly connected, Loopback0
D       150.1.3.3 [90/131072] via 136.1.17.17, 05:24:59, Vlan17
D       150.1.2.2 [90/130816] via 136.1.29.2, 05:25:29, Vlan29
D       150.1.1.1 [90/130816] via 136.1.19.1, 05:25:29, Vlan19

SW5 config:

interface FastEthernet1/0/23

To SW1
 switchport access vlan 24
 switchport mode access
 logging event spanning-tree
 spanning-tree portfast

router eigrp 111
 network 172.16.3.0 0.0.0.255
 passive-interface Loopback0

SW5#show ip int bri
Interface              IP-Address      OK? Method Status                Protocol
Vlan1                  unassigned      YES unset  up                    up      
Vlan24                 172.16.3.201    YES manual up                    up      
Vlan25                 unassigned      YES unset  down                  down  

SW5#show ip route

Gateway of last resort is not set

     5.0.0.0/24 is subnetted, 1 subnets
C       5.5.5.0 is directly connected, Loopback0
     172.16.0.0/24 is subnetted, 1 subnets
C       172.16.3.0 is directly connected, Vlan24

interface FastEthernet1/0/20
*TO SW1 

 switchport access vlan 24
 switchport mode access
 spanning-tree portfast
end 

[Jon Marshall · Accepted solution]

The IP subnet 172.16.3.0/24 is reachable via R1 so you can't use that IP subnet on SW5.

You need to use a common IP subnet between SW1 and SW5 for EIGRP to work.

Jon

[gfogleman1 · Accepted solution]

"

If the ping is not successful, as shown in Example 3-10, you should use the technologies discussed in Chapter 2, “Troubleshooting Basic Connectivity.” First, check the cabling and verify that the interfaces on connected devices are on a common subnet.

If you notice a log message such as the following that states that EIGRP neighbors are “not on common subnet,” this indicates that there is an improper IP address on one of the two EIGRP neighbor interfaces:

*Mar  28 04:04:53.778: IP-EIGRP(Default-IP-Routing-Table:100): Neighbor
192.168.100.1 not on common subnet for Serial0/0/0

If this message was received on the Branch router, you can see that the reported IP address of the neighbor does not match what you expected. However, you can still have an IP address mismatch and not see this message.

Next, check that the AS numbers are the same between neighbors. The command that starts the EIGRP process is followed by the AS number, router eigrp as_number. This AS number is significant to the entire network, as it must match between all the routers within the same routing domain. In other routing protocols, the numbering used to start the process may have only local significance (for instance, the OSPF routing protocol is started with a process-id and does not use an AS number)."

You should read this whole page it should help you understand EIGRP a little better

 http://www.ciscopress.com/articles/article.asp?p=2137516&seqNum=3