Configuring source address of TTL expired

[rasmus.elmholt]

Hi all,

I have configured a small test setup, with core routers and two routers towards a site, where the site routers are configured as router on a stick for all user VLANs.

I am using Link-Local address for all routing protocol peering, and do only have GUA addresses on loopback0 and user facing LANs

And whenever I traceroute Core-DK-R1 to the loopback address of RAN-R2 i get reply from RAN-R1 as expected, but I get it from the LAN interface G3, and not the loopback address of RAN-R1.

How do I change this behavior?

[MHM Cisco World]

you must receive reply from G2-G2 link make sure this link is UP/UP and have IP

MHM

[rasmus.elmholt]

I want to receive the reply from the Loopback interface of RAN-R1, the G2-G2 link is up, but have Link-Local addresses configured.

[MHM Cisco World]

this lab
you only need NAT to LO to make router reply with LO IP instead of interface receive the trace route
for IPv6 sorry I dont have alot info about NAT in IPv6 

MHM

[rasmus.elmholt]

INE has done a write up the the specific issue I have but for IPv4. But with no clear solution.

https://ine.com/blog/2013-09-06-modifying-traceroute-replies

For some reason the IOS takes the GUA IPv6 address of G3 as the source for the TTL expired and I cannot find a way to change that priority. Why it uses G3 as the source and not Lo0 I do not know, as none of them are in the traffic path and one is not any "closer" than the other.

[rasmus.elmholt]

Found a possible solution here for IPv4: https://community.cisco.com/t5/other-network-architecture-subjects/traceroute-replies-from-the-specified-ip-address/td-p/372742

But I have to try to migrate it for IPv6.