In message <E1829B60731D1740BB7A0626B4FAF0A65D374A86CB@XCH-NW-01V.nw.nos.boeing .com>, "Templin, Fred L" writes:
A quick comment on probes. Making the tunnel ingress probe is tempting but fraught with difficulties; believe me, I have tried. So, having the tunnel ingress fragment when necessary in conjunction with the original source probing is the way forward, and we should advocate both approaches.
RFC4821 specifies how the original source can probe with or without tunnels in the path. It does not have any RTT delays, because it starts small and then tries for larger sizes in parallel with getting the valuable data through without loss.
It's useful for TCP but it is not a general solution. PTB should not be being blocked and for some applications one should just force minimum mtu use.
Thanks - Fred fred.l.templin@boeing.com -- Mark Andrews, ISC 1 Seymour St., Dundas Valley, NSW 2117, Australia PHONE: +61 2 9871 4742 INTERNET: marka@isc.org