Can anyone help me to understand the issue what is happening here for below traceroute issue ? I am getting same hop IP address in hop 2 and 4. As from the trace report it seems 2 routers are showing each other as next hop for same destination but if it happened then a routing loop would occur but no routing loops there. Would be obliged if anyone can clarify the issue here and if possible share a sample topology with configuration / lab.
Type escape sequence to abort.
Tracing the route to 10.8.4.15
VRF info: (vrf in name/id, vrf out name/id)
1 22.214.171.124 0 msec 0 msec 0 msec
2 172.18.17.15 12 msec 12 msec 8 msec
3 172.18.17.16 16 msec 8 msec 12 msec
4 172.18.17.15 12 msec 12 msec 8 msec
5 172.18.8.9 16 msec 8 msec 16 msec
6 10.87.25.78 8 msec 12 msec 12 msec
[**] 172.18.17.15 & 172.18.17.16 are point-to-point link between two routers. where 172.18.17.16 is under my administration but 172.18.17.15 is not under my administration. So if you ask for configuration of 172.18.17.15 then I could not provide you.
It could be a loop or misconfiguration on the other end.
Is this router Test-RT under your management? This router 172.18.17.16 is sending back the packet, do you have any default route on this router, you could verify it through:
show ip cef
show ip cef exact-route <source> <destination>
Thanks for your reply. Your required information is given below inline.
Is this router Test-RT under your management?
do you have any default route on this router, you could verify it through:
MP_FW#show ip cef vrf V90 10.8.4.15
nexthop 172.18.17.15 Vlan90
MP_FW#show ip cef vrf V90 exact-route 126.96.36.199 10.8.4.
188.8.131.52 -> 10.8.4.15 => IP adj out of Vlan90, addr 172.18.17.15
Thanks for your response.
"3 172.18.17.16 16 msec 8 msec 12 msec
is having destination nat configured"
No, NAT is not configured.
can you share your routing configuration from all routers?
I would suggest to run traceroute from an end host and fire up wireshark for packet analysis. This could be a software error. If next hop router was configured to send the packets back to you then packet would never reach destination unless there is a redudant path, but with traceroute results that doesn't seem to be the case.