Limit Outgoing Bandwidth

[kyndig]

I have a full T1 and have incoming traffic such as Citrix, VPN Tunnels and clients, a Webserver, etc. I'm going to put an outgoing FTP connection over the T1 but it's going to need to transfer around 1GB of data every night. I want to setup the router (1720 with 12.0(3)T) to throttle back the FTP traffic if other traffic for the above connections are in progress. I believe that I can do a "traffic-share" on the FTP and choke it down to using a portion of the T1 but I would like it to be dynamic and only choke if other connections are in progress. Is there a way to do what I'm asking?

Thanks

 

[lambent]

Normally I would suggest a class-based weighted fair queue but I doubt your IOS version support class-based commands so I think you can try traditional rate-limiting with ACL like this:

!
access-list 101 permit tcp any any eq 20
access-list 101 permit tcp any any eq 21
access-list 101 permit tcp any eq 20 any
access-list 101 permit tcp any eq 21 any
!
int s0
rate-limit output access-group 101 800000 24000 32000 conform transmit exceed drop
!

 

[kyndig]

Could you explain what that setup will do? I'm particularly looking for a setup that will utilize the full T1 unless other connection come through then the FTP will throttle back until such time as those other connections are terminated. Will the above setup do that?

 

[vlf]

When you start getting into rate limiting, you're into QoS and it gets complicated. The nature of FTP is that it will throttle itself back without you having to do anything.

 

[kyndig]

FTP will throttle itself back of the connection is saturated?

 

[lambent]

rate-limit output access-group 101 800000 24000 32000 conform transmit exceed drop

This means that for any outbound FTP traffic defined on ACL 101, if the traffic is below 800kbps then it's allowed to pass. Also it allows a normal burst of 24000 bytes and max burst of 32000 bytes. If the traffic is above 800kbps in addition to the burst, it will be dropped.

I'm not sure about FTP throttling but with your current IOS version, if you want to avoid the bandwidth being dominated by FTP, then rate-limit with ACL is one of the ways.