Solved: EIGRP neighbor UP, routes showing but ping working only on one direction!

mazzz · ‎10-10-2018

Hi guys,

I have my two Cisco L3 switches connected via a L2 link on which I activated EIGRP 10 and the neighborship is up.

vlan 50 : 172.17.192.128/25 --------[L3_SW_2] Fa0/24====L2====Fa1/0/48 [L3_SW_1] -------- vlan 50 : 172.17.192.0/25

The interco subnet of the L2 link is : 192.168.1.200/30

From L3_SW_2, I am able to ping an IP of the vlan 50 behind L3_SW_L1 : 172.17.192.24.

But the reverse doesn't work (I tried to ping from L3_SW_2 an IP behind SW_1 : 172.17.192.130 which desn't work).

L3_SW_2#sh ip route eigr
.... output omitted ....
Gateway of last resort is 172.17.192.210 to network 0.0.0.0

      172.17.0.0/16 is variably subnetted, 3 subnets, 2 masks
D        172.17.192.0/25
           [90/28416] via 192.168.1.201, 02:00:21, FastEthernet0/24
L3_SW_2#

L3_SW_1#sh ip eigrp neighbors
EIGRP-IPv4 Neighbors for AS(10)
H   Address                 Interface              Hold Uptime   SRTT   RTO Q Seq
                                                   (sec)         (ms)       Cnt Num
0   192.168.1.202           Fa1/0/48                 14 01:57:25    7   100 0 29
L3_SW_2#

L3_SW_2#sh ip eigrp neighbors
EIGRP-IPv4 Neighbors for AS(10)
H   Address                 Interface       Hold Uptime   SRTT   RTO Q Seq
                                            (sec)         (ms)       Cnt Num
0   192.168.1.201           Fa0/24            14 01:58:10    1   200 0 34
L3_SW_2#

L3_SW_2#sh ip arp
Protocol Address          Age (min) Hardware Addr   Type   Interface
Internet 172.17.192.130          1   000c.297e.8f75 ARPA   Vlan50
Internet 172.17.192.140          9   c81f.66d7.c878 ARPA   Vlan50
Internet 172.17.192.200          -   9caf.cad2.c0c4 ARPA   Vlan50
Internet 172.17.192.210        200   4c4e.3539.77c1 ARPA   Vlan50
Internet 192.168.1.201         121   b8be.bf9e.3b44 ARPA   FastEthernet0/24
Internet 192.168.1.202           -   9caf.cad2.c0c1 ARPA   FastEthernet0/24

L3_SW_1#sh ip arp
Protocol Address          Age (min) Hardware Addr   Type   Interface
Internet 10.170.124.121          -   b8be.bf9e.3b42 ARPA   Vlan30
Internet 10.170.124.122         22   0025.90ca.1f62 ARPA   Vlan30
Internet 172.17.192.8          160   0026.b981.a277 ARPA   Vlan50
Internet 172.17.192.9            0   0026.b981.a26f ARPA   Vlan50

L3_SW_1#sh run | s eigrp
router eigrp 10
network 172.17.192.0 0.0.0.127
network 192.168.1.200 0.0.0.3
passive-interface default
no passive-interface FastEthernet1/0/48
no passive-interface Vlan50

L3_SW_2#sh run | s eigrp
router eigrp 10
network 172.17.192.128 0.0.0.127
network 192.168.1.200 0.0.0.3
passive-interface default
no passive-interface FastEthernet0/24
no passive-interface Vlan50

I need your help on this. Please ask me if you need other command outputs.

Thank you,

Richard Burts · ‎10-12-2018

Please post the details of the configuration of the devices at 172.17.192.130 and 140. I am especially interested in what is their default gateway.

HTH

Rick

HTH

Rick

View solution in original post

mljevakovic · ‎10-10-2018

Hi,

let's check to disable auto-summary under router eigrp process.

mljevakovic · ‎10-10-2018

and post sh ip route eigrp from L3_SW_1

mazzz · ‎10-10-2018

L3_SW_1#sh ip route eigrp

Gateway of last resort is 172.17.243.171 to network 0.0.0.0

      172.17.0.0/16 is variably subnetted, 5 subnets, 3 masks
D        172.17.192.128/25
           [90/28416] via 192.168.1.202, 02:19:18, FastEthernet1/0/48

And I've already applied "no auto-summary" on EIGRP 10 process on both of the switches.

Thanks

Daniele Giordano · ‎10-10-2018

Hi, can you add the output of show ip route eigrp form SW_1?

Regards.

mazzz · ‎10-10-2018

L3_SW_1#sh ip route eigrp

Gateway of last resort is 172.17.243.171 to network 0.0.0.0

      172.17.0.0/16 is variably subnetted, 5 subnets, 3 masks
D        172.17.192.128/25
           [90/28416] via 192.168.1.202, 02:19:18, FastEthernet1/0/48

And I've already applied "no auto-summary" on EIGRP 10 process on both of the switches.

The strange thing is I am able to ping from an IP of SW_1 from SW_2 but the inverse is not possible.

L3_SW_2#ping 172.17.192.8
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 172.17.192.8, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 1/2/8 ms

L3_SW_1#ping 172.17.192.130
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 172.17.192.130, timeout is 2 seconds:
.....
Success rate is 0 percent (0/5)

Daniele Giordano · ‎10-10-2018

Can you post the results of a tracert command?

Regards.

Richard Burts · ‎10-10-2018

I am somewhat confused by the explanation of the problem

From L3_SW_2, I am able to ping an IP of the vlan 50 behind L3_SW_L1 : 172.17.192.24.

But the reverse doesn't work (I tried to ping from L3_SW_2 an IP behind SW_1 : 172.17.192.130 which desn't work).

You show us routing information from one switch but not from the other switch

L3_SW_2#sh ip route eigr
.... output omitted ....
Gateway of last resort is 172.17.192.210 to network 0.0.0.0

      172.17.0.0/16 is variably subnetted, 3 subnets, 2 masks
D        172.17.192.0/25
           [90/28416] via 192.168.1.201, 02:00:21, FastEthernet0/24
L3_SW_2#

Can you post the routing information from SW1? I suspect that it may show that SW1 is not learning the subnet from SW2.

HTH

Rick

HTH

Rick

mazzz · ‎10-10-2018

Rick,

It is learnt properly:

L3_SW_1#sh ip route eigrp

Gateway of last resort is 172.17.243.171 to network 0.0.0.0

172.17.0.0/16 is variably subnetted, 5 subnets, 3 masks
D 172.17.192.128/25
[90/28416] via 192.168.1.202, 02:19:18, FastEthernet1/0/48

And I've already applied "no auto-summary" on EIGRP 10 process on both of the switches.

The strange thing is I am able to ping from an IP of SW_1 from SW_2 but the inverse is not possible.

L3_SW_2#ping 172.17.192.8
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 172.17.192.8, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 1/2/8 ms

L3_SW_1#ping 172.17.192.130
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 172.17.192.130, timeout is 2 seconds:
.....
Success rate is 0 percent (0/5)

Richard Burts · ‎10-10-2018

Thank you for the information confirming that the subnet route is learned. So that is one theory of the problem that was not correct. Next theory is the possibility is that the device at 172.17.192.130 has a firewall operating that does not allow ping. ping from SW1 is failing, so can you try ping to that IP from SW2 and see if it works?

HTH

Rick

HTH

Rick

mazzz · ‎10-10-2018

Ping from SW_2 to the local VLAN 50 (172.17.192.130) IP in quesiton is ok.

L3_SW_2#ping 172.17.192.130

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 172.17.192.130, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 1/3/8 ms

mazzz · ‎10-10-2018

See also the topology tables :

L3_SW_2#sh ip eigrp topology
EIGRP-IPv4 Topology Table for AS(10)/ID(192.168.1.202)
Codes: P - Passive, A - Active, U - Update, Q - Query, R - Reply,
r - reply Status, s - sia Status

P 172.17.192.128/25, 1 successors, FD is 2816
via Connected, Vlan50
P 192.168.1.200/30, 1 successors, FD is 28160
via Connected, FastEthernet0/24
P 172.17.192.0/25, 1 successors, FD is 28416
via 192.168.1.201 (28416/2816), FastEthernet0/24

L3_SW_1#sh ip eigrp topology
EIGRP-IPv4 Topology Table for AS(10)/ID(192.168.1.201)
Codes: P - Passive, A - Active, U - Update, Q - Query, R - Reply,
r - reply Status, s - sia Status

P 172.17.192.128/25, 1 successors, FD is 28416
via 192.168.1.202 (28416/2816), FastEthernet1/0/48
P 192.168.1.200/30, 1 successors, FD is 28160
via Connected, FastEthernet1/0/48
P 172.17.192.0/25, 1 successors, FD is 2816
via Connected, Vlan50

Daniele Giordano · ‎10-10-2018

Do you have access lists configured on the switch?

mazzz · ‎10-10-2018

No active ACL on any of the Switches!

Daniele Giordano · ‎10-10-2018

L3_SW_1#sh ip arp
Protocol Address          Age (min) Hardware Addr   Type   Interface
Internet 10.170.124.121          -   b8be.bf9e.3b42 ARPA   Vlan30
Internet 10.170.124.122         22   0025.90ca.1f62 ARPA   Vlan30
Internet 172.17.192.8          160   0026.b981.a277 ARPA   Vlan50
Internet 172.17.192.9            0   0026.b981.a26f ARPA   Vlan50

Can the SW_1 ping the connected IP 172.17.192.8? And the 172.17.192.9?
As suggested in prevoius post, the '.8' could be firewalled.

What is the '.8' device? What is the gateway? Based to the mac address is a DELL PC. Can you check for firewall or wrong/missing gateay config?

Regards