Yes, when I said IOS runs on top of Linux I was specifically
referring to
the ASR, not both the ASR and the Nexus 7K. Both platforms
were just
announced, and Cisco has decade long (at least) plans for
their life cycle,
particularly given how much was invested in their
development.
The ASR can punt packets to the RP, but it has complete
separation between
the control and data plane in my understanding.
Fred Reimer, CISSP, CCNP, CQS-VPN, CQS-ISS
Senior Network Engineer
Coleman Technologies, Inc.
954-298-1697
-----Original Message-----
From: Lincoln Dale [mailto:ltd interlink.com.au]
Sent: Thursday, March 27, 2008 2:46 AM
To: Fred Reimer; 'Lamar Owen'; nanognanog.org
Subject: RE: 10GE router resource
> That said, it
> is notable that Cisco is now running their latest
announced hardware,
> primarily the Nexus 7000's and ASR's, run a Linux
kernel and IOS on top of
> that.
Moore's Law may have helped software packet forwarding rates
but there's
still
2 to 3 orders of magnitude performance difference between
hardware &
software.
just to be clear about a few things:
in the case of Nexus 7K the control-plane runs atop of
Linux, data-plane
runs
entirely in custom packet forwarding ASICs distributed on
the I/O (linecard)
modules. N7K never drops to "software
forwarding". the first forwarding
engine in N7K does 60M PPS with all features enabled. i.e.
you could be
performing ACLs on port, VLAN & routed on both ingress
& egress, doing
netflow,
policing, QoS, whatever - its still 60M PPS.
you'll see that pps numbers scale upwards as the product
progresses through
its
roadmap.
Cisco doesn't make any secret of N7K running atop of Linux,
the reality is
that
it doesn't have to be Linux, it could be any
SMP/multi-threaded capable
POSIX-compliant kernel, it just so happens that Linux makes
sense for a
variety
of reasons.
Also, perhaps pedantic but just to be absolutely clear: N7K
doesn't run on
IOS,
it runs on NX-OS.
ASR is slightly different, it can perform packet processing
in software
(IOSd)
however that is really only meant for things that don't make
sense to
implement
in what is now called the QuantumFlow programmable
processor. e.g. if you
needed your AppleTalk or Vines running at millions of
packets/second, then
i'd
argue you have bigger problems. 
cheers,
lincoln.
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