Raymond LI - Sun Microsystems - Beijing China writes: > Andrew Gallatin å·²åå ¥: > > > > >Is the limit of 8192 tweakable in some global way? > > > > > > > > > > > You can check your system for following parameters and tune them: > > > > > > ndd /dev/tcp tcp_mss_def_ipv4 > > > ndd /dev/tcp tcp_mss_max_ipv4 > > > > > > On my system with ixgb, the MSS is 8960 and works fine. > > > > > > 1 0.00000 11.0.1.166 -> 11.0.1.212 TCP D=5001 S=52833 Syn Seq=79745287 > > > Len=0 Win=53760 Options=<mss 8960,nop,wscale 0,nop,nop,sackOK> > > > >Strange. I've got 10GA on one end, and nv21 on the other. > >Would those older versions of the OS have anything to do with it? > > > > > Maybe not, but I am not sure. Did you try to ping remote side with a > large ICMP payload, like "ping -s <remote> 12000"? And snoop to see if > the MTU you set is the same as real working MTU.
Yes, it is really sending 9000 bytes (I've appended a snoop snippet). If I remember right, the Intel nic can have a really big mtu (>12kb). What is its mtu set to? Is it set to 9000? Thanks, Drew ETHER: ----- Ether Header ----- ETHER: ETHER: Packet 10 arrived at 0:16:14.21050 ETHER: Packet size = 9014 bytes ETHER: Destination = 0:60:dd:48:b:d5, ETHER: Source = 0:60:dd:48:b:f7, ETHER: Ethertype = 0800 (IP) ETHER: IP: ----- IP Header ----- IP: IP: Version = 4 IP: Header length = 20 bytes IP: Type of service = 0x00 IP: xxx. .... = 0 (precedence) IP: ...0 .... = normal delay IP: .... 0... = normal throughput IP: .... .0.. = normal reliability IP: .... ..0. = not ECN capable transport IP: .... ...0 = no ECN congestion experienced IP: Total length = 9000 bytes IP: Identification = 9 IP: Flags = 0x4 IP: .1.. .... = do not fragment IP: ..0. .... = last fragment IP: Fragment offset = 0 bytes IP: Time to live = 64 seconds/hops IP: Protocol = 1 (ICMP) IP: Header checksum = 945c IP: Source address = 192.168.1.16, rome-my IP: Destination address = 192.168.1.15, venice-my IP: No options IP: ICMP: ----- ICMP Header ----- ICMP: ICMP: Type = 8 (Echo request) ICMP: Code = 0 (ID: 39436 Sequence number: 9) ICMP: Checksum = d5d8 ICMP: _______________________________________________ networking-discuss mailing list [email protected]
