11 Sep
1996
11 Sep
'96
4:39 p.m.
That prohibits IP src spoofing (and asymmetrical paths). ... In most networks asymmetrical routing is an indication of a bug in an IGP configuration, so early detection of the configuration problems would be an additional benefit.
In my Internet end-to-end routing study I found that fully 50% of the pairs of paths through the Internet had a major asymmetry at the end of 1995. "Major" meaning: visited at least one different city in the two directions. (30% visited at least one different AS.) This was a significant increase over the same figure for the end of 1994, 30%. So it may be quite hard to make and keep Internet routing symmetric. The paper's available from: ftp://ftp.ee.lbl.gov/papers/routing.SIGCOMM.ps.Z - Vern