I think I have found a problem with TCP when run over IPv6. I set my MSS for TCP to 1460 to allow a full 1500 byte MTU to be utilized on my systems. (Yes, I see that this does break some things like communicating via links where PMTUD is blocked and one or more links restrict MTU to some size less than 1500 bytes.
What I am specifically seeing is a packet being sent out with a TCP length of 1460. While this is fine for IPv4, it's too back for IPv6 and, as you might expect, the far end never receives this packet. There is a sysctl for net.inet.tcp.v6mssdflt which is set to 1024. This should be fine, but it appears that it is not being honored and the V4 value is always used. Am I mis-analyzing things or is TCP at least a bit broken when running over V6? (Or am I at fault for setting the large MSS because ti is honored with v6 even though there is a separate sysctl for IPv6? -- R. Kevin Oberman, Network Engineer Energy Sciences Network (ESnet) Ernest O. Lawrence Berkeley National Laboratory (Berkeley Lab) E-mail: [EMAIL PROTECTED] Phone: +1 510 486-8634 _______________________________________________ freebsd-net@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-net To unsubscribe, send any mail to "[EMAIL PROTECTED]"
