On Thu, Oct 08, 1998 at 04:19:08AM +1200, Donald Neal wrote:

Problems in getting small allocations advertised have been foreseen for years. Are we actually at the stage where we're seeing international carriers refuse to advertise anything, say, below a /18?

Stating the obvious - lots of small non-aggregated routes mean backbone and gateway routers have to use more memory and work much harder... well, actually only a little bit harder, memory utilization is usually O(N), and search time O(log n) or worse. Requiring people don't advertise lots of small piddly routes (by refusing to accept them) with the outside world is a good way to deal with this. Right now. the distribution of routing prefix sizes (from skewed my view of the world) is roughly as follows: 30126 24 6028 16 4122 23 2948 22 2921 19 2236 21 1759 20 1006 18 491 17 239 15 140 14 45 13 26 12 21 8 10 11 4 10 LHS is frequency, RHS is prefix size. So there are 30126 /24 routes, 6026 /16 routes, etc. This comes from `bgpdump | sed "s:\([^/]\+\)/\([0-9]\+\).*:\2:" | | sort | uniq -c | sort -nur' for those who are curious. Getting back to your question; I believe most of the US will accept down to /24 but other parts of the world often insist upon no smaller than /20 or /19. (Joe - can you clarify that?) It would be interesting to know just how much of a difference it would make if people were not able to advertise anything smaller than, say, /21. -Chris --------- To unsubscribe from nznog, send email to majordomo(a)list.waikato.ac.nz where the body of your message reads: unsubscribe nznog