Assymetric results from iperf across gigabit link (long)

[Mike Hunter]

On Jan 30, "Eli Dart" wrote:

> In reply to Mike Hunter <mhunter at ack.Berkeley.EDU> :

> > I switched the two pieces of hardware, and the photons still prefer going
> > uphill, so maybe there's a problem with the fiber after all.  I'd still
> > appreciate any hints on what to ask freebsd to help me figure it out.
> > (Yes, we have real fiber test gear, this is more of an experiment.)
> 
> Have you looked at interface error counts?  (netstat -inbd)  If you 
> have dirty fiber, you could just be missing/corrupting the odd packet 
> here and there, which would be enough to impact a high-bandwidth TCP 
> flow.

% netstat -inbd bge0
Name    Mtu Network       Address              Ipkts Ierrs     Ibytes    Opkts Oerrs     Obytes  Coll Drop
bge0   1500 <Link#2>      00:30:1b:b1:08:b6  1321030     0  153151700  1971658     0 2929764081     0   0
bge0   1500 fe80:2::230:1 fe80:2::230:1bff:        0     -          0        3     -        216     -   -
bge0   1500 169.229.254.1 169.229.254.140    1320970     -  134650330  1971653     - 2902160837     -   -
[snip]

> the other thing to check is if a UDP cannon has the same bandwidth 
> asymmetry, since the UDP iperf tests don't have TCP's timidity (if 
> memory serves me)....

I'll give that a shot...thanks.  Although my flood pings should have served the
same purpose (given that I fixed the icmplimit problem), right?

Thanks,

Mike