> Looking at the first few bytes in each dir of the initial TCP > handshake (with tcpdump) I see: > > 0x0000: 4500 0030 24da 0000 <= from plan9 to freebsd > > 0x0000: 4500 0030 d249 4000 <= from freebsd to plan9 > > Looks like FreeBSD always sets the DF (don't fragment) bit > (0x40 in byte 6), while plan9 doesn't (byte 6 is 0x00). > > May be plan9 should set the DF (don't fragment) bit in the IP > header and try to do path MTU discovery? Either by default or > under some ctl option.
easy enough until one encounters devices that don't send icmp responses because it's not implemented, or somehow considered "secure" that way. - erik
