[c-nsp] Monitoring CPU usage on a Sup720-3BXL (BGP)

e ninja eninja at gmail.com
Tue Sep 1 22:33:46 EDT 2009


On the contrary, as I stated below, the 'impact' of BGP scanner (a
housekeeping task executed by the main processor) on 'system' performance
will continue to diminish as more platforms become modular (distributed
architecture) and/or switch packets in hardware (i.e, independent of RP and
LC CPU eg in FPGAs)

Nothing in the aforementioned suggests that BGP scanner (a critical process
for validating the integrity of the BGP table) will EoL anytime soon.
Instead, if you note the quotes, Drew is concerned with the impact of the
CPU consumed by BGP scanner on 'system' performance. This concern does not
exist on modular platforms with distributed packet switching (c12k, hfr
etc.) that switch packets independent of main RP CPU. Put simply, even if
BGP scanner maxes out an RP CPU at 100% temporarily on a distributed
platform, it will have zero effect on packet switching (a la 'system' perf)
through the device.

Your thoughts below dwell more on enhancing the mechanism to reduce

-Eninja ;-)

On Tue, Sep 1, 2009 at 5:36 PM, Richard A Steenbergen <ras at e-gerbil.net>wrote:

> On Tue, Sep 01, 2009 at 03:56:02PM -0700, e ninja wrote:
> >
> > *BGP scanner is a housekeeping maintenance activity by the main system
> > processor. As such, its 'impact' on the 'system' should continue to
> diminish
> > as more platforms become modular (distributed architecture) and/or switch
> > packets in hardware. *
> Actually no, bgp scanner has nothing to do with platform architecture of
> packet forwarding of any kind (hardware or otherwise). It is an entirely
> software mechanism which periodically walks the entire bgp table and
> does things like verify next-hop reachability. Distributing the
> operations that it performs so that they happen when a prefix or
> next-hop changes is a much better way to handle things (improves
> convergence and reduces the periodic cpu spikes), but you'll probably
> never see it go away completely. :)
> --
> Richard A Steenbergen <ras at e-gerbil.net>       http://www.e-gerbil.net/ras
> GPG Key ID: 0xF8B12CBC (7535 7F59 8204 ED1F CC1C 53AF 4C41 5ECA F8B1 2CBC)

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