In message <[EMAIL PROTECTED]>, Abhishek Verma writes: > >Hi, > >Is the order of AS numbers (except for perhaps the first one which >denotes the AS the route was originated from) in the AS_PATH in BGP >important? In fact, does anybody even care for the first AS number >that appears in the Path? > >AFAIK, AS numbers in the BGP serves two purposes. It helps in loop >detection and it helps us count the AS Path length. > >If this is the case then the order should not really matter much. > >My question is that whether the operators care if the order, for some >reason changes? > >Eg. > >Legend: {} denotes the sequence, while [] denotes the set > >Path {1 2} [3 4] {5} > >Would somebody mind if this was represented as {1 2 5} [3 4] ? >
Any of the proposed BGP security schemes would have trouble with reordering. --Steven M. Bellovin, http://www.cs.columbia.edu/~smb