Cisco Support Community
cancel
Showing results for 
Search instead for 
Did you mean: 
Announcements

Welcome to Cisco Support Community. We would love to have your feedback.

For an introduction to the new site, click here. And see here for current known issues.

New Member

tracerouting through a tunnel question

Hi, there's something I don't understand.... when you have a tunnel interface, and traceroute to the tunnel destination - why don't you get the hops inbetween the tunnel - the real hops that the tunnel is being formed over?

Thanks, LisaG

2 ACCEPTED SOLUTIONS

Accepted Solutions

Re: tracerouting through a tunnel question

Becuase the ICMP packets are encapsulated (or enveloped) inside GRE packets and are never seen by the intermediate routers. Only when the tunnel destination is reached is the packet de-encapsulated.

If you want to trace the tunnel's path trace to the tunnel destination and not the tunnel's interface IP.

Hall of Fame Super Silver

Re: tracerouting through a tunnel question

Lisa

If you want to put in a static route that will carry traffic through a GRE tunnel then the next hop in the static route should be the tunnel interface address of the remote router.

HTH

Rick

4 REPLIES

Re: tracerouting through a tunnel question

Becuase the ICMP packets are encapsulated (or enveloped) inside GRE packets and are never seen by the intermediate routers. Only when the tunnel destination is reached is the packet de-encapsulated.

If you want to trace the tunnel's path trace to the tunnel destination and not the tunnel's interface IP.

New Member

Re: tracerouting through a tunnel question

THANKS!

New Member

Re: tracerouting through a tunnel question

By the same token, if you want to put in a static route to through an IPSEC/GRE tunnel, is the next hop supposed to be the tunnel destination, the ipsec peer or the next hop in the physical path?

THanks, Lisa G

Hall of Fame Super Silver

Re: tracerouting through a tunnel question

Lisa

If you want to put in a static route that will carry traffic through a GRE tunnel then the next hop in the static route should be the tunnel interface address of the remote router.

HTH

Rick

145
Views
0
Helpful
4
Replies
CreatePlease to create content