Traceroute replies from the specified IP address

[vadim]

I'm wondering if it's possible to configure a router to respond to all ICMP traceroute packets from the specified IP address, i.e. from its loopback interface.

The idea is to simplify network management and troubleshooting. A router should reply from the specified IP address, no matter what what interface ICMP traceroute packet is in or out.

[Georg Pauwen]

Hello,

yes this is possible. Configure the following on your routers, this will cause the router to respond with the IP address of the Loopback 0 interface to traceroutes (obviously the addresses chosen are arbitrary):

interface Loopback0

ip address 160.12.1.1 255.255.255.0

ip nat outside

!

interface Loopback1

ip address 1.1.1.1 255.255.255.255

ip nat inside

ip policy route-map TRACEROUTE

!

route-map TRACE permit 10

match ip address 100

set interface Loopback1

!

route-map TRACEROUTE permit 10

set interface Loopback0

!

access-list 100 permit icmp any any time-exceeded

access-list 100 permit icmp any any port-unreachable

!

ip nat inside source list 100 interface Loopback0 overload

!

ip local policy route-map TRACE

So basically you need to create an additional Loopback interface on your routers to serve as an inside NAT interface, the address of that Loopback interface is arbitrary.

HTH,

GP

[vadim]

Georg,

Thank you for the reply.

Are there any ways to accoplish this w/o using policy routing?