Comcast Enterprise Fiber Slow Connection Problem from TW Telecom

Fri Oct 31 19:27:28 UTC 2014

With a max bandwidth of 25 Mbps and a 40ms RTT, the max is more like 14MB/s
or 1.75 Mbps.

https://www.switch.ch/network/tools/tcp_throughput/index.html?mss=1460&rtt=80&loss=1e-06&bw=25&rtt2=35&win=64&Calculate=Calculate

But that's only if either endpoint is stuck at a 64 KB receive window. A
quick packet capture would be able to see what was happening.  Check the
TCP setup and make sure that both ends are doing TCP window scaling
properly.

John

On Fri, Oct 31, 2014 at 1:02 PM, Pedro Cavaca <pmsac.nanog at gmail.com> wrote:

> On 31 October 2014 18:32, Zachary Frederick <zcfrederick at gmail.com> wrote:
>
> > We have been having a problem receiving software releases from our
> > developer. The releases are typically around 1G in size. The developer’s
> > connection is a 100m metro fiber with TW Telecom,  our connection is a
> 25m
> > Comcast Enterprise Fiber.
> >
> > Our traffic graphs show very little utilization of our connection.
> > Typically on average we are at about 7 meg utilization of our 25.
> >
> > Every other partner that shares in our software development that receives
> > the software releases can receive the updates 3-4 times faster than we
> can.
> >
> > Typically we receive the releases at about 3mbps.
> >
>
> Are you using an application that uses TCP transport for the transfer?
>
>
> https://www.switch.ch/network/tools/tcp_throughput/index.html?mss=1460&rtt=38&loss=1e-06&Calculate=Calculate&bw=100&rtt2=80&win=64
>
> 3Mbps looks about right. Time for a tune up
>
>
> > I have tried contacting Comcast Enterprise Tech support, however I’ve
> been
> > told that if I run a speed test from my connection and the test runs at
> the
> > speed we are paying for, there is very little they are willing to look
> into.
> >
> > Can anyone check on the Comcast Routers on the Tracert below, or is there
> > anything that can be throttling this connection between the two
> connections?
> >
> > Also, our firewall and connection is able to run at the full 25. We have
> > no throttling or QOS set to prevent a good connection to our developer.
> For
> > example, we can run a multi-threaded upload, in the middle of the night,
> to
> > Amazon Glacier storage and completely saturate our connection when doing
> > so. The firewall and connection is able to handle our full bandwidth
> > capacity during that backup.
> >
> > If there is any other information I can provide to help track this
> problem
> > down, please let me know.
> >
> > Thanks in advance, everyone!
> >
> >
> > Trace Route below:
> >
> >
> >
> >
> > 1  (172.16.150.1)  1.143 ms  1.132 ms  1.122 ms
> >
> >
> > 2  (173.227.204.1)  1.585 ms  1.583 ms  1.574 ms
> >
> >
> > 3  chi2-pr1-xe-0-3-0-0.us.twtelecom.net (66.192.245.166)  10.477 ms
> > 10.485 ms 10.478 ms
> >
> >
> > 4  x-eth-0-0-4-pe05.350ecermak.il.ibone.comcast.net (75.149.230.141)
> > 10.470 ms 10.465 ms  10.457 ms
> >
> >
> > 5  he-2-1-0-0-cr01.350ecermak.il.ibone.comcast.net (68.86.86.37)  10.733
> > ms  10.731 ms he-2-0-0-0-cr01.350ecermak.il.ibone.comcast.net
> > (68.86.86.33)  12.146 ms
> >
> >
> > 6  be-10206-cr01.newyork.ny.ibone.comcast.net (68.86.86.225)  33.202 ms
> > 32.144 ms  32.127 ms
> >
> >
> > 7  68.86.91.30 (68.86.91.30)  41.508 ms  41.322 ms  41.599 ms
> >
> >
> > 8  te-0-0-0-1-sur01.greensburg.pa.pitt.comcast.net (69.139.168.26)
> > 38.196 ms te-0-0-0-3-sur01.greensburg.pa.pitt.comcast.net
> > (162.151.21.82)  44.644 ms
> te-0-0-0-0-sur01.greensburg.pa.pitt.comcast.net
> > (69.139.195.18)  38.266 ms
> >
> >
> > 9  (107.1.72.98)  39.781 ms  39.785 ms  39.912 ms
>