The question is really how isolated the IO controlelr bus is, whether
it's just a logical designation used on the IOC card, which simply plugs
into one of the two busses available on the mid-plane metal-to-metal,
or whether it's "bridged" via a PCI chipset.
In the first case, you have only two busses.
In the second case you have three busses, but one of them is subsidary
to the main busses.
What's interesting is really the distribution of function/connection
beween the PA's, midplane and IOC and NSP/NSE slots, both what is and
what was orginally architechted. Then contrase to the other PCI/PA
implementaions on for gnerations of VIP's, the 7100's vs. the 2600/3600
PCI...
There are dual-wide PA's that use only one PCI bus, can select the
least-used (CT3PA?), or use both (GEIP+). What color smoke comes
out when you plug the "PA" on the GEIP+ into a VXR?
George
> From: Gert Doering <gert@greenie.muc.de>
> To: Aaron Weintraub <aaronw@distracted.org>, cisco-nsp@puck.nether.net
> Subject: Re: [nsp] c7200 architecture question?
> References: <20010608223957.A22709@greenie.muc.de> <20010608165602.A24668@ivore.vger.com>
>
> Hi,
>
> (I take the liberty to bring cisco-nps back on CC:)
>
> On Fri, Jun 08, 2001 at 04:56:02PM -0400, Aaron Weintraub wrote:
> > http://www.cisco.com/univercd/cc/td/doc/product/core/7206/port_adp/3471pac6.htm
> >
> > agrees with what you think, which also agrees with what I think.
> >
> > There are not 3 busses in the 720x to my knowledge.
>
> Actually, that document backs *both* statements :-)
>
> Quote: "The optional ports on the I/O controllers connect to a third PCI
> bus, mb0, that connects to one of the PCI buses or to both of the PCI buses,
> depending on which network processing engine (NPE) or network services
> engine (NSE) is installed and supported in your system."
>
> So it's a separate bus, but the bandwidth used will usually be charged to
> the other bus(es).
>
> Now the interesting question is: for which NPE/NSE, where does it connect
> to? Even more fascinating :-) - but it seems that all available NPE/NSEs
> connect mb0 to mb1.
>
> Quote: "For a Cisco 7200 VXR router that has an NPE-300, NPE-400, or NSE-1
> installed, the following error messages are displayed:
> %C7200-3-PACONFIG:Exceeds 600 bandwidth points for slots 0, 1, 3 & 5"
>
> (and similar for the lesser NPEs).
>
> So the book is in error (kind of). There are a few more (it claims the
> NPE-300 runs with 300MHz, but the NPE itself claims 262 MHz), but the part
> on IOS architecture (what it's about after all) seems to be very good.
>
> gert
> --
> USENET is *not* the non-clickable part of WWW!
> //www.muc.de/~gert/
> Gert Doering - Munich, Germany gert@greenie.muc.de
> fax: +49-89-35655025 gert.doering@physik.tu-muenchen.de
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