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Re: [OT]: SSH and UDP tunnels

On Friday 02 February 2001 13:25, Hamish Moffatt wrote:
> On Thu, Feb 01, 2001 at 05:17:03PM +0100, Russell Coker wrote:
> > On Tuesday 30 January 2001 18:02, Turbo Fredriksson wrote:
> > > We're using radio links quite a lot at work, and those can have
> > > approx 4Mbit (TCP), but can come up to 6Mbit w/ UDP...
> >
> > When the TCP performance is lower than the entire bandwidth of the link
> > it is because of packet loss.  This is no surprise on a radio link!
> >
> > To increase performance you can decrease the number of packets
> > (preferred) or tweak TCP to retransmit more agressively.

Sorry, the above should read "decrease the number of packets lost".  If you 
don't have SACK enabled then loss of a small packet or of a large packet will 
have much the same affect on throughput.  One time I tested this on a 28K8 
modem link and found that a 1% packet loss halved the throughput.

> I suspect TCP also suffers due to the latency of the link.

The latency is a big problem for small transfers due to slow-start and the 
three stage handshake.  But if you want to transfer a few megs of data then 
latency SHOULD NOT be such a problem.

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