3 ms·
And ipv6? Fragmentation and mss are handled somewhat differently, iirc
by peterwwillis 7y ago
And ipv6? Fragmentation and mss are handled somewhat differently, iirc
- LinuxBender 7y agoGood point. I don't have a place to test ipv6. You would also have to create ip6tables rules to test that. If you have a test server on ipv6, please apply the rule and link it here. Well, test first, then link here. :-)
- topranks 7y agoIP fragmentation is different in IPv6 true. MSS is a TCP parameter, however, and operates at layer 4. Won’t matter if the protocol underneath is IPv4 or IPv6 in this case.
- peterwwillis 7y agoActually, it does behave differently. Never underestimate the weirdness of IPv6 ;-) From https://en.m.wikipedia.org/wiki/Maximum_segment_size https://en.m.wikipedia.org/wiki/Maximum_segment_size : "To avoid fragmentation in the IP layer, a host must specify the maximum segment size as equal to the largest IP datagram that the host can handle minus the IP and TCP header sizes.[2] Therefore, IPv4 hosts are required to be able to handle an MSS of 536 octets (= 576[3] - 20 - 20) and IPv6 hosts are required to be able to handle an MSS of 1220 octets (= 1280[4] - 40 - 20)." So it seems like one needs to clamp tcpv4 to at least 536, and tcpv6 to at least 1220. (tcpv6 is common shorthand for TCP over IPv6, similar to udpv6 and icmpv6)