[AusNOG] CPU - when to upgrade

[Mike Everest]

Tip for all: use http://talk.mikrotik.com.au for this kind of topic :-}

> -----Original Message-----
> From: AusNOG [mailto:ausnog-bounces at lists.ausnog.net] On Behalf Of Rhys
> Cuff (Latrobe I.T)
> Sent: Friday, 6 April 2018 1:00 PM
> To: ausnog at lists.ausnog.net
> Subject: Re: [AusNOG] CPU - when to upgrade
> 
> Ohhhh  setting a rule at the top to fasttrack established connections made a
> huge difference.
> Thanks for the tip
> 
> 
> 
> -----Original Message-----
> From: Mike Everest [mailto:mike at duxtel.com]
> Sent: Friday, April 6, 2018 12:31 PM
> To: Rhys Cuff (Latrobe I.T); ausnog at lists.ausnog.net
> Subject: RE: [AusNOG] CPU - when to upgrade
> 
> Hi Rys,
> 
> With routerOS, throughput limitation due to cpu really only happens when it
> completely runs out (i.e. 100% utilisation) - when you hit 100, router can't
> keep up with incoming packets and so some packets begin to be dropped.
> That can have a follow-on effect that TCP stream initiators will start to pare
> back the transmit rate accordingly so if your router is CLOSE to 100% but not
> quite, it can still indicate a throughput limit.  But 70% - 80% is not usually a
> problem for throughput.
> 
> Other actions as already suggested, like fastpath and/or review of firewall
> rule order can make a huge difference - even adding a 'permit established' at
> the top of the forward chain can make a massive difference if you don’t
> already have it ;)
> 
> Cheers!
> 
> Mike.
> 
> > -----Original Message-----
> > From: AusNOG [mailto:ausnog-bounces at lists.ausnog.net] On Behalf Of
> > Rhys Cuff (Latrobe I.T)
> > Sent: Friday, 6 April 2018 11:44 AM
> > To: ausnog at lists.ausnog.net
> > Subject: Re: [AusNOG] CPU - when to upgrade
> >
> > Hi Guys
> >
> > Thanks very much for the responses.
> > We are a very small wireless ISP (around 2000 customers) and run
> > MikroTik router kit (I know I know...) I can see its normally firewall
> > and routing process's that use most.
> > Running around 300mbps on the routers in question.
> > I can certainly upgrade, just wasn’t sure if it was worth it.
> > MikroTik don’t have much kit that is small and runs 24v.
> >
> > Thanks again
> >
> > Rhys
> >
> >
> >
> >
> > -----Original Message-----
> > From: Graeme Allen [mailto:mail at graemeallen.com]
> > Sent: Friday, April 6, 2018 11:22 AM
> > To: Rhys Cuff (Latrobe I.T)
> > Cc: ausnog at lists.ausnog.net
> > Subject: Re: [AusNOG] CPU - when to upgrade
> >
> > Hi Rhys,
> >
> > If you are looking at an MRTG style graph, then as Jim points out you
> > are probably looking at a 5 minute rolling average, and the peaks will
> > very likely be much higher and yes possibly impacting performance.
> >
> > For a more instant view of the CPU, do a "show proc cpu history", this
> > will show you the spikes (assuming csco).
> >
> > Assuming the box you are using is not just under-powered, you need to
> > look at what is hitting the cpu and see if you can control/remove it.
> >
> > Chasing "links that don't seem to go as hard as they should", oh man,
> > that's such a can of subjective worms......
> >
> >
> > On Fri, April 6, 2018 10:51 am, Jim Woodward wrote:
> > > On 06-04-2018 10:21, Rhys Cuff (Latrobe I.T) wrote:
> > >
> > >
> > > Hi Rhys,
> > >
> > >
> > > If it's a Cisco I have found that once you start hitting 70% you'll
> > > start to see Latency creep up, this in turn will likely to have an
> > > overall effect on achievable speeds.
> > >
> > > If the 70% figure is an average then peaks may be quite a bit
> > > higher, I would consider working on a plan to upgrade the device(s)
> > > or do the usual process of looking at your configuration to see if
> > > you have any misconfigured/redundant ACL's or or routing policies
> > > that may be eating into your CPU performance.
> > >
> > > Kind Regards,
> > >
> > >
> > > Jim.
> > >
> > >
> > >> FROM: AusNOG [mailto:ausnog-bounces at lists.ausnog.net] ON BEHALF
> OF
> > >> Rhys Cuff (Latrobe I.T)
> > >> SENT: Friday, April 6, 2018 10:19 AM
> > >> TO: ausnog at lists.ausnog.net
> > >> SUBJECT: [AusNOG] CPU - when to upfrade
> > >>
> > >>
> > >> Hi Guys
> > >>
> > >>
> > >> When you have a router and cpu is hitting about 60 - 70% with
> > >> traffic load would that impact speeds?
> > >>
> > >> I've got a few links that don't seem to go as hard as they should,
> > >> but I can't find the
> > >> reason._______________________________________________
> > >>
> > > AusNOG mailing list
> > > AusNOG at lists.ausnog.net
> > > http://lists.ausnog.net/mailman/listinfo/ausnog
> > >
> > >
> >
> >
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