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Ping times on a router during File Transfer (text version)

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Anonymous
February 28, 2005 6:20:25 PM

Archived from groups: alt.comp.networking.connectivity,alt.comp.networking.firewalls,alt.comp.networking.routers (More info?)

I am trying to troubleshoot a network issue with one of my clients and I'm
finding a very strange occurrence.

The customer is complaining of slow performance and application timeouts
using a .NET application my company provides. During one function of the
application, there is a lot of data transfer to the local workstation,
cached on the local workstation, to fill in WinForms that user uses to
change or save information to the remote database.

During the initial data transfer, the customer reports that the application
seems to stop responding. The WinForm is on the screen, but the mouse
hourglasses and appears to be hung.

When we try to do the same function on the same database from another
location, it works, completing in more time than we would like it to
complete, but it does finish. My developers are aware of this problem, but
that does not stop us from looking at the apparent timeout issue.

I've narrowed the problem to the ISP or the router. When we connect
directly to the router, circumventing the enterprise firewall, the
application acts the same way.

To test the Internet issue, I remoted into a workstation and initiated an
FTP session. I downloaded a 53MB file to the workstation and the ISP
remoted into the router to monitor CPU usage, memory usage, and other
parameters. The file downloaded in about 4 minutes with no interruptions
that I could see. The ISP tech reported no unusual problems.

I began the transfer again and pinged the router. My ping times were
250-400ms. This is not a good amount of time to me, so I stopped the FTP
and pinged the router again. This time, my ping times were 40-60ms.

I did this back and forth, and I consistently got bad results during FTP and
good results without the FTP.

I had the ISP tech repeat my tests as I started and stopped the FTP. He
pinged other locations and got similar results.

The router is a Cisco 2600 series router. It services about 30 users in
this customer's office.

What can cause a router to delay a ping request for such a long period of
time during a file transfer? I've repeated this experiment on other
customers and did not receive these results; ping times remained the same
during and outside of the FTP session.

Please email me at rtocci@amsworld.com as well as responding to this post.
Thank you for your help.

--
Richard Tocci
College Station, TX

All inbound and outbound e-mails are scanned for viruses. I probably did
not send you a virus, but if you receive an e-mail with a virus from me, let
me know.


--
Richard Tocci
College Station, TX

All inbound and outbound e-mails are scanned for viruses. I probably did
not send you a virus, but if you receive an e-mail with a virus from me, let
me know.
Anonymous
March 1, 2005 7:49:12 PM

Archived from groups: alt.comp.networking.connectivity,alt.comp.networking.firewalls,alt.comp.networking.routers (More info?)

In article <11272oq6j1hqm07@corp.supernews.com>, Richard Tocci wrote:

>During the initial data transfer, the customer reports that the application
>seems to stop responding. The WinForm is on the screen, but the mouse
>hourglasses and appears to be hung.

Run a network sniffer such as ethereal and see what is being blocked. Look
at the TCP window sizes, and packet ACK numbers.

>To test the Internet issue, I remoted into a workstation and initiated an
>FTP session. I downloaded a 53MB file to the workstation

>The file downloaded in about 4 minutes with no interruptions
>that I could see. The ISP tech reported no unusual problems.

about 221 KB/second. OK

>I began the transfer again and pinged the router. My ping times were
>250-400ms. This is not a good amount of time to me, so I stopped the FTP
>and pinged the router again. This time, my ping times were 40-60ms.

How big is the "pipe" you are trying to stuff this through. How much other
traffic is going over that link at the same time? What kind of routers
between you, and what priority do they give ICMP compared to TCP?
IN THEORY, you can reduce the size of the packets, which increases the
overhead of the connection, but does allow more spaces between the packets
to slip in your ping and it's reply. However, I suspect you have some
other problem.

>I've repeated this experiment on other customers and did not receive these
>results; ping times remained the same during and outside of the FTP session.

Do they have the same sized pipe? Are they trying to stuff the same amount
of stuff over the link at the same time? Does one have a bunch of clueless
fools who are mailing PowerPoint presentations back and forth, or running
HTML instead of plain text?

>Please email me at rtocci@amsworld.com as well as responding to this post.

Post here - get your answer here.

Old guy
!