Sloooow FTP download

danc_101

I have a 2008 R2 server which runs various FTP downloads from an FTP server on the web. Suddenly the 'FTP get' has got very very slow (0.5 kbps). I've checked all network devices in between the 2008 server and as far as I can the FTP server on the internet. I've tried the FTP from another server in the same VLAN and its fine.

I've updated the NIC drivers, checked speed / dulpex settings / AV etc . A network capture shows many 'DUP ACK' and 'TCP Retransmissions'

Anyone seen this issue before ?

Thanks

instant000

danc_101 wrote: »

I have a 2008 R2 server which runs various FTP downloads from an FTP server on the web. Suddenly the 'FTP get' has got very very slow (0.5 kbps). I've checked all network devices in between the 2008 server and as far as I can the FTP server on the internet. I've tried the FTP from another server in the same VLAN and its fine.

I've updated the NIC drivers, checked speed / dulpex settings / AV etc . A network capture shows many 'DUP ACK' and 'TCP Retransmissions'

Anyone seen this issue before ?

Thanks

Based on what you say so far, you have a crappy connection.

Duplicate acks and retransmissions are what TCP does to try to combat a suck connection. (That is, if it's repeating the acks like that, it's trying to let you know that it's not getting it.) The TCP then throttles down, and basically tries to send less and less at a time, until it is totally throttled down.

See this link: http://www.ietf.org/rfc/rfc2581.txt

If the servers are indeed on the same VLAN, switch around the network cables (be mindful of port security), and see if the problem follows the switch port/cable or not.

Just to be clear:

You're saying you get vastly different download from two different servers in the same server room, on the same VLAN, correct?

And another thing ... there is adequate disk space/CPU/memory and everything on this server, right?

danc_101

instant000 wrote: »

Based on what you say so far, you have a crappy connection.

Duplicate acks and retransmissions are what TCP does to try to combat a suck connection.

If the servers are indeed on the same VLAN, switch around the network cables (be mindful of port security), and see if the problem follows the switch port/cable or not.

Thanks but I forgot to mention that I can FTP and copy files from / to this server internally fine, thus ruling out cabling..