[c-nsp] Weird throughput issue

Andrew Miehs andrew at 2sheds.de
Mon Jul 25 01:50:51 EDT 2016

How did you go with the tcpdump? Did it show anything?

On Sun, Jul 24, 2016 at 11:13 PM, Curtis Piehler <cpiehler2 at gmail.com> wrote:
> Oh right.   I temporarily move the wan to an svi on the cat4900
> On Jul 24, 2016 6:09 PM, "Andrew Miehs" <andrew at 2sheds.de> wrote:
>> On Sun, Jul 24, 2016 at 7:11 PM, Curtis Piehler <cpiehler2 at gmail.com>
>> > The only difference in the setup between both sites is 1) the carrier(s)
>> > that is used and 2) the site with the problem trunks through a Cat4948
>> > initially before hitting the 6504.  We have other customers off of the
>> > Cat4948 who report no issues.  I have looked over the Cat4948 config and
>> > there is nothing apparent that would hinder TCP taffic.
>> So based on this description, you believe you only have one
>> difference, which is the link from the carrier itself.
>> I would recommend confirming with them whether they have incorrectly
>> provisioned your link, and set policers/ qos settings incorrectly. I
>> would also confirm with them that they haven't oversubscribed part of
>> their backbone.
>> Have you run tcpdump on your iperf instance to see what is happening?
>> This will show you pretty quickly whether you are experiencing
>> retransmits, or if one side has not enabled window scaling.

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