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New Member

Download speed over site to site VPN-tunnel is very slow?

Hi All,

could you please find me an answer for the below issue.

we have two datacentres say LA and Mia, where we have a site to site VPN between them, each of the datacentre has broadband  of 10Mbps line.

the issue with tthe client is when he is trying to copy a file of 864MB from LA to MIa the speed which he getss to download is 74Kbps. could you please say me how to answer this question. as the VPN tunnel between two datacentres are UP and connectivity is fine.

CLIENT:

while copinfg a filr  from source LA: 172.16.55.189 to  Dest Mia:10.10.8.50. But unfortunately, the speed which he gets to  download is 74Kbps with this speed  he couldnt be able to  download the requested files from LA servers to Mia serverss. Every time connection time out.

Please find the attacheed sheet which specifies the speed of downloading he is getting.

File size:864MB

4 REPLIES
Super Bronze

Download speed over site to site VPN-tunnel is very slow?

Disclaimer

The   Author of this posting offers the information contained within this   posting without consideration and with the reader's understanding that   there's no implied or expressed suitability or fitness for any purpose.   Information provided is for informational purposes only and should not   be construed as rendering professional advice of any kind. Usage of  this  posting's information is solely at reader's own risk.

Liability Disclaimer

In   no event shall Author be liable for any damages whatsoever (including,   without limitation, damages for loss of use, data or profit) arising  out  of the use or inability to use the posting's information even if  Author  has been advised of the possibility of such damage.

Posting

Assuming the site-to-site data copy is using TCP, often the issue is TCP receiver isn't supporting a TCP window large enough for the bandwidth delay product.  Assuming RTT of 100 ms @ 10 Mbps, you need 125 KB of buffer space.  (NB: it also help to insure you can buffer TCP slow start on you network bottlenecks.)

Another issue that commonly impacts performance across VPNs is packet fragmentation.  (NB: adhereing to recommendation for avoiding packet recommendation avoid this issue.)

Lastly, when and if working with broadband connections that don't match physical interface bandwidth, providers may police traffic rate in such away that nominal bandwidth capacity isn't obtainable.  (NB: this can be avoided by shaping to your contracted bandwidth.)

New Member

Download speed over site to site VPN-tunnel is very slow?

HI Joseph,

TCP window size could you please explain me a bit more.

If we consider in mia location a two servers conected to one switch and downloading a file will TCP window size come in to picture as im able to download the file pretty quickly,

Is tcp window size will only applicable on the wan interfface.

appreciate your suppport.

thanks

srikanth

Super Bronze

Download speed over site to site VPN-tunnel is very slow?

Disclaimer

The    Author of this posting offers the information contained within this    posting without consideration and with the reader's understanding that    there's no implied or expressed suitability or fitness for any  purpose.   Information provided is for informational purposes only and  should not   be construed as rendering professional advice of any kind.  Usage of  this  posting's information is solely at reader's own risk.

Liability Disclaimer

In    no event shall Author be liable for any damages whatsoever  (including,   without limitation, damages for loss of use, data or  profit) arising  out  of the use or inability to use the posting's  information even if  Author  has been advised of the possibility of such  damage.

Posting

Google BDP (bandwidth delay product).

It's not an issue of WAN vs. LAN bandwidth, but bandwidth and latency.  BDP might be the same for a 10 Mbps LAN and a T1 WAN, and not a problem, but might be a problem with a 10 Mbps WAN or a gig LAN.

New Member

Re: Download speed over site to site VPN-tunnel is very slow?

Check with your ISP your upstream bandwidth. 10mbps on both site may just be downstream bandwidth. You might have 1mbps or less.

Sent from Cisco Technical Support iPhone App

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