Cisco Nuts wrote: > > Hello, > Is the ebgp-multihop default value = 255 ?? > From all the examples that I have seen and done, it has always > been set to a > number ex. 2 or 200 or 255 etc. but doing an example from CCO, > is just uses > the cmd. # neighbor a.b.c.d ebgp-multihop - with no value and > it works!! > Thus, I am assuming that the ebgp-multihop default value = 255?? > Anyone?? > Thank you. > Sincerely, > CN
Notice if you configure ebgp-multihop with no parameter, that the "show ip bgp neighbors" output for that neighbor says: External BGP neighbor may be up to 255 hops away. If you specify a number, such as 2, you'll see: External BGP neighbor may be up to 2 hops away. Not putting a parameter on the command makes life easier, but then again, BGP network operators don't care about easiness. :-) However, if you are going to put a parameter, you need to know the number of hops, which can be a little confusing because just going to a loopback on another router instead of a directly-connected interface counts as a hop. I checked with a sniffer by the way. On the 3-way handshakes, the routers use 255 for the IP TTL regardless, at least on my routers which are running IOS 11.0. That surprised me. But after the 3-way handshake, they start setting the TTL to 1 (if no ebgp-multihop), 255 (if ebgp-multihop is configured with no parameter), and the correct number (if ebgp-multihop is configured with an exact number). That seems like a misbehavior to me (i.e. setting the TTL to 255 for the three-way handshake). You could establish a connection with a router even though you couldn't do anything. You could establish so many that you could cause a DOS. I'll have to do some more testing of this. Priscilla > > > > > > > > _________________________________________________________________ > STOP MORE SPAM with the new MSN 8 and get 2 months FREE* > http://join.msn.com/?page=features/junkmail > > Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=66172&t=66157 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
