Re: Growth rate

DES Challenge Lists (
Fri, 25 Apr 1997 05:28:50 -0600

> On Fri, 25 Apr 1997, Christian Foisy (7086) wrote:
> > Another good reason is that the server(s) seem unable to keep up with
> > the load: I'm tracing all in/out packets going through updrelay here
> > (few dozens machines) and many requests from clients do not get a
> > reply, and it is getting worse.
> Ahh! Do not mistake the server with the connection between the two
> of you. The internet is the weakest link in the system, amplified by the
> fact we're using UDP packets (they're small, light, and love to
> dissapear). So my guess would be that the requests are due to networking
> problems as compared to the server itself. Rocke could tell me i'm full
> of it, (the server might be dying) but as a second server hasn't been
> brought up, then it must still be doing its job.
> Adam

The server is not having any trouble keeping up with the current pace
of keyspace assignment. The server is running about 20% CPU-bound,
and a backup server is standing by.

There have always been a small number of clients who check out huge
amounts of keyspace without returning it. It's rather annoying.

I've tried several different strategies at the keyserver to deal
with it.

With the previous strategy, multiple clients at a single IP address
would receive duplicate keyspaces when they first started. Thereafter,
they received unique keyspaces.

As of yesterday, every client gets its own unique keyspace, but the
strategy limits the number of requests that can come from a single
IP address in a given period of time. (Details aren't important,
as they will be tuned over the next day or two. :)

That's why Christian saw a sudden increase in dropped packets:

Christian's "problem" is that he is behind a firewall, and all of
his machines appear to be one IP address. He is starting oodles
of clients all at once. And yes, the server was dropping oddles
of his packets. Once the clients are out of phase with each other,
everything should be normal.

If you're not behind a firewall (using UDPRELAY or equivalent), you
shouldn't see this problem.

If you're not starting and killing your clients via cron, you shouldn't
see this problem.

If you're going through the deschall-gateway, this problem should be
much less pronounced.

I will be tuning the server over the next day or two to make this
problem much less pronounced.

Others seeing excessive dropped packets are most likely seeing the
effects of an Internet that is overloaded from time-to-time.

Thanks to all!

-- Rocke