[c-nsp] Router 7200 + GE-PE module

[Gert Doering]

Hi,

On Sun, Jan 29, 2012 at 07:42:09PM +0000, Andy Litzinger wrote:
>   do you know if there is any good documentation on this?  The stuff on cisco's site seems intentionally vague- it speaks only of 'bandwidth points' and that the PA-GE interface offers "high capacity".
> 
> http://www.cisco.com/en/US/products/hw/modules/ps2033/products_data_sheet09186a0080091ce7.html#wp39066
> http://www.cisco.com/en/US/docs/routers/7200/configuration/7200_port_adapter_config_guidelines/3875In.html#wp1031141

Well, it's more "the platform is over 10 years old, and it was never
the fastest box in the world" - and reading cisco-nsp and hearing people
complain about lack of throughput on PA ports :-)

In theory, a PCI bus should be able to nearly do 1Gbit/sec (33 MHz x 32bit),
but that would completely saturate the box - and I don't think either the
PAs nor the PCI interface of the 7200 is that highly optimized.

The bandwith point scale suggest that each PCI bus in the system should
be able to go up to 600 Mbit/s, but you'll never be able to sustain 
that bit rate without microbursts overrunning buffers and CPU.

> Also, what is the rated BW per port on the NPE-G2?  you hint that you 
> don't get full Gig there either.  Is that purely because of 
> oversubscription, or can you literally not get a full gig on a single port?

The NPE-G2 should be able to do GigE line rate on each single port, but
not on all 4 of them simultaneously (maybe for full size packets and 
"no features on", but not for internet mix).  Thus, not all of them are 
fully loaded on the original poster's box :-)

gert

-- 
USENET is *not* the non-clickable part of WWW!
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Gert Doering - Munich, Germany                             gert at greenie.muc.de
fax: +49-89-35655025                        gert at net.informatik.tu-muenchen.de
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