Force9/Alcatel Router Problem

[Glen Cumming]

Hi There,

I've got a problem that a customer of ours is experiencing and was
wondering if anyone can shed some light on it.

Essentially we have a linux box which is acting as a web-server
connected to an adsl router, the ISP is force9.

Initially access to the box from the outside world works fine -
slightly lumpy connection speeds but works fine.

Then after some random period of time the connection to the box starts
to fail - for example the main text body of a page will load but all
the subsequent connections for gifs etc either take a very long time
or fail completely - this continues until no requests are served at
all.

Users inside the network can still access the outside world without
any problems.

The linux box is happily accessible inside the customers network, so
its looks like some kind of uplink issue.

Resetting the router resolves the problem, but it soon grinds to a
halt again.

The router is an alcatel 3881 v2.7d s/w - this has already been
changed once.

We've done a few bits'n'pieces to see if they would help such as move
the server away from ports 80/8080 in case there was a cache and also
modify the mtu unit length to the value specified on the force9
website but to no effect.

So far force9 have not been able to provide any illumination on the
matter.

Our linux box works perfectly well on other adsl routers/isp
combinations.

I'm limited in what I can do to try and debug the system as we are
physhically a long way from the customer and ssh to our server often
fails, also we've very limited experience of using adsl routers etc
(mostly they just work).

Anyone had problems like this and know any solutions?

Any replies greatly appreciated.

Cheers,

Glen

[David J Edgar]

"Glen Cumming" <gl...@cumming66.freeserve.co.uk> wrote in message
news:4ed3363d.0304...@posting.google.com...

Try disabling HTTP 'keep alives' on you web server.

Dave.

[PlusNet Support Team]

Glen Cumming wrote:

> Our linux box works perfectly well on other adsl routers/isp
> combinations.

This is the bit that confuses me...

Can you try and disable Explicit Congestion Notification if it's enabled?
I've heard a couple of customers have had issues with our service under
linux with this kernel module enabled.

Regards,
Mike

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[Glen Cumming]

Hi,

Thanks for the reply.

> Can you try and disable Explicit Congestion Notification if it's enabled?
> I've heard a couple of customers have had issues with our service under
> linux with this kernel module enabled.

^^^
Its not enabled, I've checked in /proc/sys/net/ipv4/tcp_ecn and its 0.

I've also tried disabling http 1.1 in IE (ok not quite what previous
poster suggested but I think it should do the same thing) but that
makes no difference.

I can be logged in via ssh when things grind to a halt and watch the
apache access log and I can see that the requests are not reaching the
box at all.

If I use wget to get the main page it works fine time and time again,
note that wget only does a single requests and does not attempt to
load the other links on the page (i.e. gifs and style sheets). If I
try the same thing with IE the main page comes through, mabey one gif
and the rest will be broken links - its then locked up again (for 30
seconds or so - probably until all the connectsion are closed). Its
almost as if the simultaneous requests are killing it (nuts now my ssh
connection has locked up).

Aaaarg....frustrating.

Any other ideas greatly appreciated.

Cheers,

Glen