Re: [mpls-linux-general] Cisco traceroute issues
Status: Beta
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jleu
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From: James R. L. <jl...@mi...> - 2003-03-10 17:30:34
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This is good info. When you do not set 'mpls ip propagate-ttl' the LDP lsp from PE1-PE2 is being treated as one hop, therefore mpls-linux is not seeing a MPLS packet with a TTL of 1, so it is not really participating the trace route (you'll never see it in the hop list). By setting 'mpls ip propagate-ttl' the P router will 'participate in the traceroute' and will see a MPLS packet with TTL 1. In this case what do you expect to happen? If you are tracing from CE1-CE2, P does not know about the IP space associated with the CE routers, so it cannot generate a ICMP message. One option (which I think Cisco implements) is to generate a ICMP message, and forward it to the end of the LSP and let the egress (PE2 in this case) handle forwarding it back to CE1. Either way, mpls-linux should not crash when faced with this situation I'll fix that. If you wouldn't mind. Could you submit a bug report at http://sf.net/projects/mpls-linux/? Thank you On Mon, Mar 10, 2003 at 11:07:35AM -0600, Ben Groff wrote: > > > I have a test network setup using two Cisco 2610 routers running IOS > version 12.2(8)T5. These routers are configured as PE routers with a CE > router attached to each 2610. The PE routers have a MPLS-VPN configured > with MP-BGP and can successfully pass traffic from the CE to the other CE. > I have verified that the label stacks are functioning correctly. I have a > linux box running the latest public release version of mpls-linux, ldp, > and zebra 0.93a. The linux box is acting as a P router. > > The lab setup looks something like this: > > CE1 -- PE1 -- P -- PE2 -- CE2 > > > Everything works fine in this setup until I run a traceroute on the CE > towards the other CE. When I do this, the linux box will lock hard. > There are no crash messages, no kernel panics, just completely frozen. I > managed to trace the issue to the following command on the cisco routers: > mpls ip propagate-ttl. When I disable that command, the traceroute works > fine. I can reproduce this problem at will. Is there any further > information you all would like to see in regards to this issue? > > Thanks, > -Ben > > > > ------------------------------------------------------- > This sf.net email is sponsored by:ThinkGeek > Welcome to geek heaven. > http://thinkgeek.com/sf > _______________________________________________ > mpls-linux-general mailing list > mpl...@li... > https://lists.sourceforge.net/lists/listinfo/mpls-linux-general -- James R. Leu |