[c-nsp] Cat 6500 vs ASR

[Pete Lumbis]

At a (very) high level the way the Sup720/6k works is ASIC driven with
TCAM. TCAM is programmed to hold things that are looked up (Netflow, CEF,
NAT) and the ASIC is able to do a handful of things really really well
(which is why you can get multi-10Gig interfaces). The downside is that the
ASIC is incredibly dumb and if it wasn't designed do to that originally it
can't be improved to do it. For example, as I mentioned, the ASIC can look
in TCAM to see if there is an existing NAT entry, but it can't create one.
This means the first packet in a NAT flow gets punted to the CPU and then
the ASIC can forward the rest of that flow in hardware.

By contrast the ASR is based on what Cisco calls the "QFP". This is a
Network Processor, which lives somewhere between a general purpose CPU that
is in a server or ISR router and the ASIC. Because it has a more general
purpose architecture NPs are generally cheaper to produce, but lack the
horse power you can get out of an ASIC. The advantage you get with an NP is
that you can program is much more easily and have a lot more flexibility.
This gives the ASR better QoS options than the Sup720, as well as the
ability to do all NAT operations on the QFP. The downside is that it
doesn't scale as well and so you'll have a lower PPS ceiling than with
something like Sup720. The ESP number indicates the forwarding speed of the
box (ESP 5 = 5 Gbps, bidirectional). I think the ESP-100 is the highest end
ESP that is out today. Since the ASR is centralized, the best case is
100gbps bidirectional. You can contrast that to a 6k where you can install
DFCs and get 40 gbps per slot (sorta).

So in short, if you need raw throughput or port density with few features
I'd look at the 6k. If you need a more feature rich device, at the trade
off of throughput, then the ASR might be the right platform for you.


On Thu, Jan 17, 2013 at 5:46 PM, Chuck Church <chuckchurch at gmail.com> wrote:

> I'm curious about this question as well.  I did visit FN, and was able to
> grab features provided by both the 3.6 ASR image in addition to the 15.1
> image for Sup720.  Unfortunately FN doesn't have image info for the IOS-XE
> on the Sup2T.  I'm wondering if the list is a little incomplete though,
> since the 6500 image didn't mention any AAA features.  I find that hard to
> believe.
>
> Chuck
>
> -----Original Message-----
> From: cisco-nsp-bounces at puck.nether.net
> [mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Raymond Burkholder
> Sent: Thursday, January 17, 2013 4:02 PM
> To: 'cisco nsp'
> Subject: Re: [c-nsp] Cat 6500 vs ASR
>
> > For reference, I have been saying exactly what everyone here has been
> > saying, but my boss wants the specifics :-)
>
> How about www.cisco.com/go/fn
>
> That is the feature navigator.    Other than that, I think you'd have to
> find some CiscoLive presentations.
>
> >
> >
> >
> > Date: Thu, 17 Jan 2013 15:28:55 -0500
> > Subject: Re: [c-nsp] Cat 6500 vs ASR
> > From: alumbis at gmail.com
> > To: markjohn20 at hotmail.com
> > CC: nick at foobar.org; cisco-nsp at puck.nether.net
> >
> > I think the problem is that the devil is in the details.
> >
> > Both boxes will support most of the same features (VPLS, NAT, Netflow,
> > QoS). For every feature listed here there are caveats that need to be
> > kept
> in
> > mind when comparing the boxes (ex. for NAT 6k punts the first packet
> > to built state, ASR1k doesn't. ASR1k will scale to larger NAT table
> sizes).
> >
> >
> > -Pete
> >
> >
> > On Thu, Jan 17, 2013 at 2:44 PM, Mark John <markjohn20 at hotmail.com>
> > wrote:
> >
> >
> >
> >
> >
> > Dear oh dear!
> >
> >
> >
> > Yes, admittedly two very different platforms with different core
> > purposes, but in term of support for logical features which can be
> > compared side-by- side, that's not too difficult if you the info. Some
> > gave an example
> earlier of
> > support for VPLS, but never mind :-)
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> > > Date: Thu, 17 Jan 2013 12:41:40 +0000
> >
> > > From: nick at foobar.org
> >
> > > To: markjohn20 at hotmail.com
> >
> > > CC: cisco-nsp at puck.nether.net
> >
> > > Subject: Re: [c-nsp] Cat 6500 vs ASR
> >
> > >
> >
> > > On 17/01/2013 11:56, Mark John wrote:
> >
> > > > True. So, ASR 1xxx
> >
> > >
> >
> > > "Compare two completely different things.  Be specific."
> >
> > >
> >
> > > Oh my.
> >
> > >
> >
> > > Nick
> >
> > >
> >
> >
> >
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