In your previous mail you wrote: > => d(bidir tunnel) = 2 * d(MN,HA) + 2 * d(HA,CN) > d(triangular) = d(MN,HA) + d(HA,CN) + d(MN,CN) > d(optimization) = 2 * d(MN,CN) > and we always have d(MN,CN) <= d(MN,HA) + d(HA,CN) > so d(optimization) <= d(triangular) <= d(bidir tunnel) > and even stronger 2 * d(triangular) = d(optimization) + d(bidir tunnel) > i.e. in my poor English the cost/performance of triangular routing > is at the middle of bidirectional tunneling and routing optimization. In theory, yes. But the question is, does it really make that much of a difference as long as at least one way is "unoptimized"? => the same difference than when both ways are unoptimized or optimized. Difference in distance is the same, difference in byte overhead too. This is true for all points with one exception: protocol complexity because triangular routing has roughly the same complexity than bidirectional tunneling.
Practice? I don't think there's much difference in bidir tunnel/triangular routing; I doubt e.g. TCP would be able to get much better performance from triangular than from bi-dir (and there are goals like hiding your origins that triangular cannot solve). => I can't see how TCP is involved. I believe your argument is different: if the traffic is very asymmetrical (more on one way than on the other), you prefer to have it on the optimized way... I am afraid the real argument against the triangular routing is this discussion itself because the main triangular routing advantage comes from the (future) fact that HAO is supported by every IPv6 nodes. With enough FUD this shall never become true and the advantage shall vanish... I'd like to get the opinion of IPv6 implementors (if they don't filter out this boring discussion) about HAO (for it, against it, will/won't implement it, will/won't enable it by default, etc). Regards [EMAIL PROTECTED] -------------------------------------------------------------------- IETF IPng Working Group Mailing List IPng Home Page: http://playground.sun.com/ipng FTP archive: ftp://playground.sun.com/pub/ipng Direct all administrative requests to [EMAIL PROTECTED] --------------------------------------------------------------------
