[NCLUG] lftp help needed

Michael Milligan milli at acmeps.com
Mon Jan 6 17:55:04 MST 2003

John L. Bass wrote:
> The choice between 15000 and 16384 is the choice between the delivered data
> rate to the filesystem, or the data rate at the network interface. There is
> about a 10% overhead in TCP/IP for ftp frames including ACK's. 15KBytes/sec
> results in about 128kbps at the network interface, and 16.4KBytes/sec results
> in about 144kbps at the network interface.

Good point.

> Read the difference between limit-rate and limit-total-rate if you plan to
> issue multiple background ftp sessions or use parallel > 1 for a mirror command.

Another good point w.r.t. running multiple connections in parallel.  But I 
still find lftp's rate limiting function to be rather sloppy.  Can't be 
helped really given it sits on the application side.

When I need/want to be precise about bandwidth allocation, I do egress 
traffic shaping using a packet scheduling discipline on my Linux firewall. 
The Hierarchical Token Bucket (HTB) class-based scheduler (along with the 
MARK function of netfilter/iptables) works quite well for this and is 
finally included in the 2.4.20 kernel (and later).


Michael Milligan  --  Free Agent  --  milli at acmeps.com

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