Wireshark · Wireshark-users: Re: [Wireshark-users] FTP - TCP Previous segment lost, TCP Dup ACK, TCP Retransmission

[Sake Blok <sake@xxxxxxxxxx>]

On Thu, Dec 06, 2007 at 10:18:47PM -0500, Hansang Bae wrote:
> Reynolds, Tom wrote:[snip: moving datacenter.  using ftp to test the 
> throughput]
> > 
> > Downloads and uploads (from a DSL line) to Philadelphia.  Everything is 
> > great.  We get a solid 3 Mb/s download and a solid 750k upload. 
> > 
> > Downloads from Valley Forge to the DSL line are very poor, with almost 
> > double the time to download the same 10 MB file.  There are frequent 
> > drops from the 3Mb/s range to about 500k.   I have actually seen worse 
> > than this.
> > 
> > After looking at the sniffer logs, here is what I see:   (middle 10 
> > packets 8950-8959, right about the time of the bandwidth drops). 
> > Note that I am getting a ton of: 
> > TCP Previous segment lost
> > TCP Dup ACK
> > TCP Retransmission

Have you checked the physical port settings for the servers and switches
in Valley Forge? It could just be the server on fixed (100Mb/Full duplex?)
and the switch on auto (or vice versa).

Do you have multiple servers at Valley Forge? Do they have good network
performance between them?

Cheers,


Sake