I'm once again considering trying to improve on the test-ipv6.com PMTUD failure detection. Due to limitations on the client side I can't use raw sockets to generate test packets. The client is JavaScript and runs in a browser; all I can do is try fetching urls from multiple locations, each with a different MTU.
I know that the various operating systems tend to cache any PMTUD issues that they can detect; future connections to that destination will use smaller packets accordingly. What I can not see to find is an adequate description of what granularity this gets cached with. /128? /64? Also, I the absence of Packet Too Big messages, what does each OS do? If anyone has pointers, please share. It will affect what and how I can improve the site, given the restrictions I have with the client side. -- Jason Fesler, email/jabber <jfes...@gigo.com> resume: http://jfesler.com "Give a man fire, and he'll be warm for a day; set a man on fire, and he'll be warm for the rest of his life."