[c-nsp] NPE-G1 PPS limitations

[Ross Vandegrift]

On Thu, Apr 17, 2008 at 11:35:13AM -0700, dpinkard at AccessLine.com wrote:
> Would one expect gigE to gigE traffic local to the NPE-G1 to scale higher
> than that?

Yea, I would expect that.  I don't understand all of the
architechtural issues on the 7200 series in great detail, but it seems
that either the PCI bus that line cards use isn't really up to doing
GigE, or the controllers on the PA-GE doesn't scale well.

The router I saw this on originally had it's primary ingress interface
on the NPE and primary egress interface on the PA-GE.  When we swapped
a low-traffic interface on the NPE with the PA-GE, we suddenly saw our
packet loss drop to nothing.  So I can say with pretty much 100%
confidence that local to the NPE will scale much better than the
PA-GE.

Ross



> 
> -----Original Message-----
> From: Ross Vandegrift [mailto:ross at kallisti.us] 
> Sent: Thursday, April 17, 2008 11:27 AM
> To: dpinkard at AccessLine.com
> Cc: cisco-nsp at puck.nether.net
> Subject: Re: [c-nsp] NPE-G1 PPS limitations
> 
> On Wed, Apr 16, 2008 at 01:51:48PM -0700, dpinkard at AccessLine.com wrote:
> > I'm stuck with older hardware (VXRs, and GSRs) and trying to plan for its
> > eventual demise... 
> > 
> > At what point should one expect the G1 to actually top out on PPS? I've
> > heard anecdotal claims of 200-225Mbps with voip-sized (200byte) packets
> for
> > something around 125kpps, which is dramatically lower than Cisco's
> > optimistically marketed number of 1Mpps. 
> > 
> > So assuming a 20 line ACL, how should one expect it to scale for traffic
> > going to/from ports on the gigE interfaces? Should this performance drop
> > when traffic is headed to the PCI buses?
> 
> 7200 CPU starts to get pretty beat up and you climb into those numbers, but
> it gets far worse if you're using PA-GE modules.  The PA-GE interfaces
> top out at around 400Mbps before they start dropping packets, even if
> the pps is low.  Your pps numbers are very close to what I recall,
> though we were hitting the bps issue more.
> 
> The gig interfaces on the NPE are substantially beefier and scaled
> beyond this limit, but I doubt that you'll get as much more out of
> them for pps issues.
> 
> 
> -- 
> Ross Vandegrift
> ross at kallisti.us
> 
> "The good Christian should beware of mathematicians, and all those who
> make empty prophecies. The danger already exists that the mathematicians
> have made a covenant with the devil to darken the spirit and to confine
> man in the bonds of Hell."
> 	--St. Augustine, De Genesi ad Litteram, Book II, xviii, 37

-- 
Ross Vandegrift
ross at kallisti.us

"The good Christian should beware of mathematicians, and all those who
make empty prophecies. The danger already exists that the mathematicians
have made a covenant with the devil to darken the spirit and to confine
man in the bonds of Hell."
	--St. Augustine, De Genesi ad Litteram, Book II, xviii, 37