[nsp] ATM problems (DSL)

[Stephen J. Wilcox]

On Fri, 4 Apr 2003, Charles Sprickman wrote:

> 
> On Fri, 4 Apr 2003, Chris Roberts wrote:
> 
> > > On Fri, 4 Apr 2003, Temkin, David wrote:
> > >
> > > > What's the CPU like on the router?
> > >
> > > Looking at cricket, about 40% peak time and down to about 20% overnight
> > > and weekends.  Packet loss remains about the same.
> >
> > What routing protocols is this router running (if any?). Look for CPU spikes
> > on the router with 'sh proc cpu' run a good few times over a five minute
> > period.
> 
> BGP and OSPF.  Two BGP peers, total of maybe 20Mb/s.  I've got cricket
> looking at cpu and it's not really spiking.  Both of our upstreams are
> stable, with no bgp resets.  Our ospf area encompasses only 3 routers, and
> doesn't really change.

Hmm. If you're polling by snmp you are getting 5 minute averages not per second 
peaks.. if you have full BGP tables thats 250000, regardless of stability the 
router will scan once per minute and it will only last a few seconds which wont 
show on averages...

Steve

 > 
> > This doesn't explain why it may only affect some customers. I'm guessing
> > that only certain customers have complained (e.g. those trying to run gaming
> > or time/packet loss sensitive applications).
> 
> We have about 9 people that have complained.  We have another random
> sampling of about 20 customers in smokeping that we watch and it's like
> night and day...
> 
> Thanks for all the help folks.
> 
> Charles
> 
> > >
> > > > If I were you I'd up the hold-queue to 150 just for giggles (hold-queue
> > 150
> > > > on the interface)
> > >
> > > I'll give it a shot and see what happens...
> > >
> >
> > Increasing the hold queue may alleviate the problem temporarily if it is
> > this, however long term I would look at either moving this router into an
> > NSSA area if it isn't already or removing BGP from the router if it doesn't
> > really need to run it if it is this problem. I've run into a lot of problems
> > with routers doing this, and if you're running particularly time sensitive
> > applications (game servers, etc being DSL customers) increasing the hold
> > queue may not alleviate the perceived problems as you trade loss for (bad)
> > jitter.
> >
> > Also, if it is running OSPF, 'sh ip ospf stat' can be your best friend.
> >
> > Cheers,
> > Chris.
> >
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