[c-nsp] 7500 slot configuration

[Rodney Dunn]

On Wed, Mar 15, 2006 at 01:36:36PM +0200, rafi-cnsp2 at meron.openu.ac.il wrote:
> 
> On Tue, 14 Mar 2006, Rodney Dunn wrote:
> 
> > Date: Tue, 14 Mar 2006 10:59:10 -0500
> > From: Rodney Dunn <rodunn at cisco.com>
> > To: David Coulson <david at davidcoulson.net>
> > Cc: cisco-nsp <cisco-nsp at puck.nether.net>
> > Subject: Re: [c-nsp] 7500 slot configuration
> > 
> > I've never seen it matter in the real world.
> 
> 1) IIRC what can be a problem in the real world is the cbus utilization
> the "real world" cybus capacity is around 600 Mb/sec
> (that is on a 7513 router with all VIP4 it may be less with VIP2)
> so splitting the cards in order to load share between the 2 buss
> is probably a good idea

In the real world you most likely never see a traffic pattern
that can get to those rates on a VIP based card before you overrun
the VIP CPU to switch the packets. I've seen it once ever with a
database replication software that was sending full sized packets
at very high rates. And even then I wasn't 100% sure it wasn't the
VIP CPU that was still the bottleneck for the bursty traffic and not
the bus throughput.

If you are looking at those kind of rates you shouldn't be on a 75xx.

> 
> 2) Also AFAIK the GEIP is based on the VIP2/50 - so you'll probably hit a 
> performance wall if your input+output traffic significantly exceeds 300Mb/sec 
> for one of the GEIP or for that matter any single slot since you're 
> using VIP2/50s for the other slots - in particular 2*T3+FE in one VIP is 
> pushing it

Again it's almost not about the throughput it's about the pps because
that is the point that gets almost every software forwarding platform
that is out there.

The GEIP is much less than the GEIP+ b/c it's on a VIP2-50 CPU vs.
the VIP4 CPU as you said. Again as we've discussed too many times
on this alias. If you want real GE connectivity at high rates don't
use a 75xx. Most likely you will be disappointed as the traffic
load goes above the copule hundred Mbps and 20-30 kpps rates.

Rodney

> 
> -- 
> HTH,
>   	Rafi
> 
> 
> >
> > btw, you can't have a VIP with no PA in it.
> >
> > Rodney
> >
> >
> > On Tue, Mar 14, 2006 at 10:49:49AM -0500, David Coulson wrote:
> >> 	I've got a couple of 7507s here, which are going to end up with
> >> identical configs.
> >>
> >> 2x RSP4
> >> 2x GEIPs
> >> 1x VIP2-50 w/ PA-MC-T3
> >> 1x VIP2-50 w/ PA-2T3 + PA-FE
> >> 1x VIP2-50 w/ nothing
> >>
> >> My question is this. I know the 7500s have a bus on slots 0+1 and slots
> >> 4+5+6, however I'm trying to figure out if there is a performance hit
> >> going between the two buses. My first thought is to put all the active
> >> hardware in 4+5+6 (GEIP+MC-T3+2T3/FE), so it's on the same bus, and the
> >> backup stuff in 0(GEIP), however I'm unsure if this is the best way to
> >> go.
> >>
> >> So, does it even matter where cards go in these routers? If so, what's
> >> the best way to organize it?
> >>
> >> David
> >>
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> >
> 
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