Re: connection startup issues with recent DragonFly.

[Matthew Dillon <dillon@xxxxxxxxxxxxxxxxxxxx>]

:On Sat, Jan 22, 2005 at 11:01:00AM -0800, Matthew Dillon wrote:
:>     Ahhh... sounds like an ARP issue!
:> 
:>     And indeed, if I arp -d the ARP entry to leaf on my workstation, then
:>     ssh again, the 3 seconds delay occurs again.  And after that, no delay.
:> 
:>     Jeff, I think the arp code is dropping the packet(s) triggering the
:>     ARP event or otherwise doing something with it so it does not reach the
:>     target machine.  Could you take a look?
:
:OK, sounds very familiar. With my rl(4) cardbus card I get pretty repeatable
:network problems. Can you run a tcpdump on the originating machine?
:In my case, I can see the incoming ARP packages with tcpdump, but they are
:not processed.
:
:Joerg

    I don't think it's related to the IF driver.  My boxes are using the
    SK driver.

    I'm not sure what the 'IP0 truncated-ip' thing is, but my guess is that
    it's the ARP code trying to push out the original packet that 
    triggered the ARP action and mangling it terribly.  The TCP retry takes
    care of it later but it's this mangled packet that's causing the delay.

    Here's the packet trace.  MAKE YOUR WINDOW WIDE! :-)

					-Matt
					Matthew Dillon 
					<dillon@xxxxxxxxxxxxx>

ORIGINATING MACHINE (ssh to target machine, after arp entry to target removed):

    11:39:50.711220 IP 216.240.41.44.1126 > 216.240.41.2.53:  30702+ A? leaf.backplane.com. (36)
    11:39:50.711716 IP 216.240.41.2.53 > 216.240.41.44.1126:  30702* 2/3/3 CNAME[|domain]
    11:39:52.367360 IP 216.240.41.44.1127 > 216.240.41.2.53:  45645+ AAAA? leaf.dragonflybsd.org. (39)
    11:39:52.367673 IP 216.240.41.2.53 > 216.240.41.44.1127:  45645* 0/1/0 (100)
    11:39:52.367925 IP 216.240.41.44.1128 > 216.240.41.2.53:  45646+ A? leaf.dragonflybsd.org. (39)
    11:39:52.368223 IP 216.240.41.2.53 > 216.240.41.44.1128:  45646* 1/3/3 A[|domain]
    11:39:52.368463 arp who-has 216.240.41.26 tell 216.240.41.44
    11:39:52.368637 arp reply 216.240.41.26 is-at 00:0c:6e:bd:e9:78
    11:39:52.368660 IP0 truncated-ip - 434 bytes missing! 0.0.69.0 > 0.64.162.247: icmp
    11:39:55.360667 IP 216.240.41.44.1087 > 216.240.41.26.22: S 1504170666:1504170666(0) win 57344 <mss 1460,nop,wscale 0,nop,nop,sackOK,nop,nop,timestamp 8232266 0>
    11:39:55.360918 IP 216.240.41.26.22 > 216.240.41.44.1087: S 217395811:217395811(0) ack 1504170667 win 57344 <mss 1460,nop,wscale 0,nop,nop,timestamp 280072492 8232266,nop,nop,sackOK>
    11:39:55.360971 IP 216.240.41.44.1087 > 216.240.41.26.22: . ack 1 win 57920 <nop,nop,timestamp 8232266 280072492>
    11:39:55.368665 IP 216.240.41.26.22 > 216.240.41.44.1087: P 1:42(41) ack 1 win 57920 <nop,nop,timestamp 280072493 8232266>
    11:39:55.368939 IP 216.240.41.44.1087 > 216.240.41.26.22: P 1:42(41) ack 42 win 57920 <nop,nop,timestamp 8232266 280072493>
    11:39:55.370458 IP 216.240.41.26.22 > 216.240.41.44.1087: P 42:674(632) ack 42 win 57920 <nop,nop,timestamp 280072493 8232266>

TARGET MACHINE (steady state):

    11:38:43.431067 arp who-has 216.240.41.26 tell 216.240.41.44
    11:38:43.431094 arp reply 216.240.41.26 is-at 00:0c:6e:bd:e9:78
    11:38:43.431342 IP0 truncated-ip - 434 bytes missing! 0.0.69.0 > 0.64.162.247: icmp
    11:38:46.423275 IP 216.240.41.44.1087 > 216.240.41.26.22: S 1504170666:1504170666(0) win 57344 <mss 1460,nop,wscale 0,nop,nop,sackOK,nop,nop,timestamp 8232266 0>
    11:38:46.423308 IP 216.240.41.26.22 > 216.240.41.44.1087: S 217395811:217395811(0) ack 1504170667 win 57344 <mss 1460,nop,wscale 0,nop,nop,timestamp 280072492 8232266,nop,nop,sackOK>
    11:38:46.423550 IP 216.240.41.44.1087 > 216.240.41.26.22: . ack 1 win 57920 <nop,nop,timestamp 8232266 280072492>
    11:38:46.431137 IP 216.240.41.26.22 > 216.240.41.44.1087: P 1:42(41) ack 1 win 57920 <nop,nop,timestamp 280072493 8232266>
    11:38:46.431570 IP 216.240.41.44.1087 > 216.240.41.26.22: P 1:42(41) ack 42 win 57920 <nop,nop,timestamp 8232266 280072493>
    11:38:46.432831 IP 216.240.41.26.22 > 216.240.41.44.1087: P 42:674(632) ack 42 win 57920 <nop,nop,timestamp 280072493 8232266>
    11:38:46.433091 IP 216.240.41.44.1087 > 216.240.41.26.22: P 42:682(640) ack 674 win 57288 <nop,nop,timestamp 8232266 280072493>
    11:38:46.529379 IP 216.240.41.26.22 > 216.240.41.44.1087: . ack 682 win 57920 <nop,nop,timestamp 280072503 8232266>