Bandwidth issues in the Sprint network
gonnason at gmail.com
Wed Apr 9 14:04:32 UTC 2008
On Tue, Apr 8, 2008 at 9:19 AM, Brian Raaen <braaen at zcorum.com> wrote:
> I have been using the Java based versions of the speed test. At this point I
> have had some Sprint people get in contact with me so I will see what they
> find. Thank you for all your help to everyone.
> Brian Raaen
> Network Engineer
> braaen at zcorum.com
> > On Monday 07 April 2008, you wrote:
> > I am currently having problems get upload bandwidth on a Sprint circuit. I
> am using a full OC3 circuit. I am doing fine on downloading data, but
> uploading data I can only get about 5Mbps with ftp or a speedtest. I have
> tested against multiple networks and this has stayed the same. Monitoring
> Cacti graphs and the router I do get about 30Mbps total traffic outbound, but
> individual (flows/ip?) test always seem limited. I would like to know if
> anyone else sees anything similar, or where I can get help. The assistance I
> have gotten from Sprint up to this point is that they find no problems. Due
> to the consistency of 5Mbps I am suspecting rate limiting, but wanted to
> > know if I was overlooking something else.
> > --
> > Brian Raaen
> > Network Engineer
> > braaen at zcorum.com
Most of the speed test sites on the Internet basically issue a HTTP
GET request to a server and time the download. For upload they utilize
a HTTP POST via a CGI script and time that. The main issue I have with
these speed tests is that they only use a single TCP session for data
transfer, which is fine if you have a large or self adjusting TCP
window size and a relatively low latency link.
However for high capacity links, it is unlikely (but possible) that
you are planning to use a single TCP session and consume all the
available capacity. Realistically you will have a few dozen
server/applications/users and produce hundreds/thousands of TCP
sessions which will fully utilize the link.
For our PtP customers that have concerns regarding capacity, I
generally they suggest setup iperf at both ends and run a few tests
with multiple TCP sessions so they can independently verify. Hopefully
Sprint will take your concerns to heart and assist you with testing.
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