8-STABLE outgoing scp stalling frequently.

[Jonathan Chen]

Hi,

I've noticed that on a recent 8-STABLE/amd64, scp(1) appears to be
stalling very frequently. This is the output from a "scp -v -v"
of a 300Mb file from a local to a remote within an internal network:

    [.. authentication negotiation ...]
    debug2: channel 0: open confirm rwindow 0 rmax 32768
    debug2: channel 0: rcvd adjust 131072
    debug2: channel_input_status_confirm: type 99 id 0
    debug2: exec request accepted on channel 0
    Sending file modes: C0700 367085370 file1
    file1        0%  192KB 140.0KB/s   42:39 ETAdebug2: channel 0: rcvd adjust 65593
    file1        0%  256KB  78.2KB/s - stalled -debug2: channel 0: rcvd adjust 81920
    file1        0%  336KB  41.6KB/s - stalled -debug2: channel 0: rcvd adjust 81920
    file1        0%  416KB  26.9KB/s - stalled -debug2: channel 0: rcvd adjust 81920
    file1        0%  496KB  17.1KB/s - stalled -debug2: channel 0: rcvd adjust 81920
    file1        0%  576KB  12.4KB/s - stalled -debug2: channel 0: rcvd adjust 81920
    file1        0%  656KB  11.3KB/s - stalled -debug2: channel 0: rcvd adjust 81920
    file1        0%  736KB   9.7KB/s - stalled -debug2: channel 0: rcvd adjust 81920
    file1        0%  816KB   9.9KB/s - stalled -debug2: channel 0: rcvd adjust 81920
    file1        0%  896KB   9.0KB/s - stalled -debug2: channel 0: rcvd adjust 81920
    file1        0%  976KB   9.5KB/s - stalled -debug2: channel 0: rcvd adjust 81920

/etc/ssh/ssh_config is untouched. Oddly enough a scp of a remote file
to the local machine is blindingly fast.

Does anyone know what's happening here? Any tips on how to track down
what the problem is? The network config appears to be fine - fetch(1) will
have downloads speeds of up to 300KB/s.

Cheers.
-- 
Jonathan Chen <jonc at chen.org.nz>
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