:o That's a bit convoluted but I get the idea. There's got to be a more elegant solution.
Thanks B From: kelle...@gmail.com Date: Wed, 17 Apr 2013 23:26:15 -0400 Subject: Re: [OSL | CCIE_RS] BGP TTL Expiration To: baldeepbi...@hotmail.com CC: ccie_rs@onlinestudylist.com (config-router) neighbor 1.2.3.4 ttl-security 1 Now do a "debug ip packet <acl> detail" with a BGP-only ACL on your far-end router (1.2.3.4) and see what the TTL is when the packet arrives. 255 - TTL of the packet = number of hops in between you. This works because TTL-Security sets the TTL to 255 before transmitting, and only allows packets that have a TTL of 255 - <setting>. In this way, the packets will still arrive for your capture, but the neighborship won't establish until you enter a more sane TTL setting than "1". Hope this helps, -Keller Keller Giacomarro kelle...@gmail.com On Wed, Apr 17, 2013 at 10:48 PM, Baldeep Birdy <baldeepbi...@hotmail.com> wrote: Guys, Haven't posted for a while as I've been immersing myself in labs. The fun of IPv6, Multicast and MPLS :) but I'm getting there. Back to point, I was doing a lab where I had some eBGP peers that were multiple hops apart. When I configured everything up I forgot to add the eBGP multihop command. After some troubleshooting I figured out my school boy error but it sparked a question. Scenario is that you have peers multi hops away, but you have no visibility of the internetwork connecting them. So you dont know how many hops there are i.e. traceroute doesnt work. When you use the show ip bgp neighbours command it tells you that the peer is multi hops away, but doesnt give more info. Is there a debug that gives you info on what to set the TTL to? I know the lazy answer is just to use 255 in the multihop command, but what if we want to be very specific. TTL Boundary esque !? If the peer is 5 hops away but I set my multihop command to 4 my peering wont come up!? so again, is there a debug to give me a helpful hint? Cheers Bal _______________________________________________ For more information regarding industry leading CCIE Lab training, please visit www.ipexpert.com Are you a CCNP or CCIE and looking for a job? Check out www.PlatinumPlacement.com http://onlinestudylist.com/mailman/listinfo/ccie_rs _______________________________________________ For more information regarding industry leading CCIE Lab training, please visit www.ipexpert.com Are you a CCNP or CCIE and looking for a job? Check out www.PlatinumPlacement.com http://onlinestudylist.com/mailman/listinfo/ccie_rs
