> yes, it definitely needs to be a fixed number. in other words, IPv6 > link MTU should not be computed based on IPv4 PMTU (which is dynamic). > PMTUD assumes that link MTUs are stable enough.
I know of no such assumption. In fact PMTUD is designed deal with routing using different paths with different MTU over time (and even at the same time) by taking the minimum of the reported MTUs. Dealing with an interface which changes MTU falls out of that design for free. > by using IPv4 PMTU > as basis for IPv6 link MTU, IPv6 link MTU will be affected by IPv4 > routing changes. it will have negative impact to IPv6 PMTUD. What exactly is the negative impact? Using a dyanmic MTU for the tunnels has the positive impact of being able to send larger, thereby fewer, packets when the path supports the larger MTU. Erik -------------------------------------------------------------------- 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] --------------------------------------------------------------------
