[LARTC] Problems at end of slow satelite link

[LARTC] Problems at end of slow satelite link

[Ben Clewett]

Newbe hoping this is the correct area to post.

I've been reading the LARTC HOWTO, but at 110 pages, I am finding it 
difficult to know where to start.  I hope you may be able to surgest a 
starting place to a couple of problems I am having.

I am dealing with the slow end of a satelite ADSL.  This is 'lumpy', 
with huge latency (1 to 30 sec), 10% dropped packets, huge but 
intermittent bursts of packets, and generally a pile of poo.   The 
supplier (BT) is of course no help, so we have to live with what we have.

I have tried limiting the bandwidth with a Tocket Bucket Filter with 
almost no effect.

What I think I need is to agressivelly schedule SSH and Telnet before 
all other TCP connections.  Others I don't care about.  There are I see 
many scheduling options, can any member surgest how I might atchive this?

The second problem I have is that my connection keeps terminating 
(Telnet, SSH) with 'Connection closed by foreign host', with no message 
in logs.  Always during streaming of data.  Some part of the kernel is 
getting tired of waiting for the other end to respond, or possible a 
buffer overflow?  Again, if any member may surgest how this can be 
countered with extream predudice, I would be extreamly greatful.

Regards, Ben Clewett.


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Re: [LARTC] Problems at end of slow satelite link

[Stef Coene]

On Thursday 06 March 2003 17:33, Ben Clewett wrote:
> Newbe hoping this is the correct area to post.
>
> I've been reading the LARTC HOWTO, but at 110 pages, I am finding it
> difficult to know where to start.  I hope you may be able to surgest a
> starting place to a couple of problems I am having.
>
> I am dealing with the slow end of a satelite ADSL.  This is 'lumpy',
> with huge latency (1 to 30 sec), 10% dropped packets, huge but
> intermittent bursts of packets, and generally a pile of poo.   The
> supplier (BT) is of course no help, so we have to live with what we have.
>
> I have tried limiting the bandwidth with a Tocket Bucket Filter with
> almost no effect.
>
> What I think I need is to agressivelly schedule SSH and Telnet before
> all other TCP connections.  Others I don't care about.  There are I see
> many scheduling options, can any member surgest how I might atchive this?
>
> The second problem I have is that my connection keeps terminating
> (Telnet, SSH) with 'Connection closed by foreign host', with no message
> in logs.  Always during streaming of data.  Some part of the kernel is
> getting tired of waiting for the other end to respond, or possible a
> buffer overflow?  Again, if any member may surgest how this can be
> countered with extream predudice, I would be extreamly greatful.
I think it's best you create a htb setup with different classes.  One of the 
classes needs a higher priority so the packets in that classes are send 
first.  Next you need to put the ssh/telnet/syn/ack packets in that classes.  
All needed information can be found in the LARTC howto.  And you can also 
find more info on www.docum.org.

Stef

-- 

stef.coene@docum.org
 "Using Linux as bandwidth manager"
     http://www.docum.org/
     #lartc @ irc.oftc.net

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Re: [LARTC] Problems at end of slow satelite link

[Ben Clewett]

Stef Coene wrote:
> I think it's best you create a htb setup with different classes.  One of the 
> classes needs a higher priority so the packets in that classes are send 
> first.  Next you need to put the ssh/telnet/syn/ack packets in that classes.  
> All needed information can be found in the LARTC howto.  And you can also 
> find more info on www.docum.org.

This is Hierarchical Token Bucket, explained in section 9.4.5 of the 
HOWTO document?

I was rather hoping you were going to surgest something else, as this is 
not in my kernel... :)

I will however check out the documentation in some more detail.  There 
are a few unresolved questions I have on this pleasent protocol.

Like I notice it claims to scale up to the available bandwidth in 
proporsion to the allocated bandwidth.  I need to know how it calculates 
this bandwidth, as our link shows all the properties of the available 
bandwidth being proporsional to 1/S noise.  Ie, unpredictable and 
un-averagable.

I would like to know also whether HTB scales down, if bandwidth becomes 
throtted by our unpredictable pipe.  And in either case, whether it's 
possible to have a protected channel, like an admin channel, which 
doen't scale up or down with the rest, staying at, say, 16kbit...

All of which I will now try and find out.  And then attempt to get it 
into my kernels at either end. :)

Ben

The biggest mistory of my link-from-hell is the ping.  This shows either 
a latency of 800ms, or 1.5 seconds, or up to 30 seconds when the line 
goes on-hold for a while.  About once every two minutes.  Yet Telnet/SSH 
consistently give latency far far more than this, of about 10 to 60 
seconds consistetly.

If anybody can surgest a reason for this, I think this is likelly to be 
at the heart of any fix I can find...

Regards again...


> 
> Stef
> 


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Re: [LARTC] Problems at end of slow satelite link

[Stef Coene]

On Monday 10 March 2003 12:00, Ben Clewett wrote:
> Stef Coene wrote:
> > I think it's best you create a htb setup with different classes.  One of
> > the classes needs a higher priority so the packets in that classes are
> > send first.  Next you need to put the ssh/telnet/syn/ack packets in that
> > classes. All needed information can be found in the LARTC howto.  And you
> > can also find more info on www.docum.org.
>
> This is Hierarchical Token Bucket, explained in section 9.4.5 of the
> HOWTO document?
>
> I was rather hoping you were going to surgest something else, as this is
> not in my kernel... :)
You can also use cbq.  But htb is easier to configure.  Or go for the 2.4.20 
kernel.  That has htb support.

> I will however check out the documentation in some more detail.  There
> are a few unresolved questions I have on this pleasent protocol.
>
> Like I notice it claims to scale up to the available bandwidth in
> proporsion to the allocated bandwidth.  I need to know how it calculates
> this bandwidth, as our link shows all the properties of the available
> bandwidth being proporsional to 1/S noise.  Ie, unpredictable and
> un-averagable.
>
> I would like to know also whether HTB scales down, if bandwidth becomes
> throtted by our unpredictable pipe.  And in either case, whether it's
> possible to have a protected channel, like an admin channel, which
> doen't scale up or down with the rest, staying at, say, 16kbit...
You can configure a protected channel with a minimum bandwidth.

> All of which I will now try and find out.  And then attempt to get it
> into my kernels at either end. :)
>
> Ben
>
> The biggest mistory of my link-from-hell is the ping.  This shows either
> a latency of 800ms, or 1.5 seconds, or up to 30 seconds when the line
> goes on-hold for a while.  About once every two minutes.  Yet Telnet/SSH
> consistently give latency far far more than this, of about 10 to 60
> seconds consistetly.
Have you tried screen?  If you start screen, you get a virtual console.  You 
can work in it like you normally do, but if your session is terminated, you 
can reconnect to the same screen session with "screen -r".  Very handy if you 
have a faulty connection :)

> If anybody can surgest a reason for this, I think this is likelly to be
> at the heart of any fix I can find...
I have no idea ..

Stef

-- 

stef.coene@docum.org
 "Using Linux as bandwidth manager"
     http://www.docum.org/
     #lartc @ irc.oftc.net

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