I don't believe TTL is necessarily reflected in a ping reply. Most devices set the TTL of their response based on their own IP stack's configuration, not based on the TTL if the incoming request.
Ping a few things around the Internet. I get wildly different incoming TTLs from each target. Bob -- Sent from my iPhone, please excuse any typos. On Apr 18, 2013, at 12:49 AM, Keller Giacomarro <[email protected]> wrote: > You could, of course, just ping the remote site with a set TTL and see what > it is when it arrives. But I thought a pure BGP solution was more fun. =) > > Keller Giacomarro > [email protected] > > > On Wed, Apr 17, 2013 at 11:55 PM, Baldeep Birdy > <[email protected]>wrote: > >> :o >> >> That's a bit convoluted but I get the idea. There's got to be a more >> elegant solution. >> >> Thanks >> B >> >> ------------------------------ >> From: [email protected] >> Date: Wed, 17 Apr 2013 23:26:15 -0400 >> Subject: Re: [OSL | CCIE_RS] BGP TTL Expiration >> To: [email protected] >> CC: [email protected] >> >> >> (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 >> [email protected] >> >> >> On Wed, Apr 17, 2013 at 10:48 PM, Baldeep Birdy >> <[email protected]>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 _______________________________________________ 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
