[nsp] Sup 720

[Simon Leinen]

On Wed, 9 Apr 2003 09:53:44 +0300 (EEST), Pekka Savola <pekkas at netcore.fi> said:
> Looking at the slideware, a few questions spring to mind:

> - the performance improvement is only obtained when using new
> linecards, it seems with dCEF/aCEF -- otherwise it's back to 32(?)
> Mpps.

That not enough for you?

> - it is not clear whether new interface modules will support both 
> "dCEF720" and "aCEF720".

It's either/or.  For instance, there are two new 10 GE line cards, one
is aCEF720 (the four-port one I think) and the other dCEF720 (the
two-port one).

> - it is not clear whether you can enable dCEF on a system which has other 
> than dCEF720 or dCEF256 linecards (and performance tradeoffs of that)

There are several separate questions here.  Maybe someone else can
correct me if I'm wrong.

I expect that the "256" and "720" cards can be mixed on the same
fabric, and that you still get the best throughput possible for each
combination of source/destination card.  I.e. that you still get 40
Gbps between twp "720" cards even when you have "256" cards in the
chassis.  This is how I read "When a CEF256 or dCEF256 module is
detected, the switch fabric will automatically connect those modules
by offering 8-16 Gbps of bandwidth to each module, as applicable" (as
opposed to, falling back to 8-16 Gbps for all modules).  The "256"
cards may reduce the total available bandwidth of the fabric, but I
don't know whether there are situations where this matters.

You can certainly combine dCEF forwarding and centralized forwarding.
Packets arriving on a dCEF-enabled card will have the forwarding
decisions (and NetFlow etc.) done on the card (on the DFC), packets
arriving on other cards will have this done on the Supervisor720/PFC3.

> - it is not clear whether you can enable aCEF on a system which has
> other than aCEF720 linecards (and perfomance tradeoffs of that)

Not as I understand it.  aCEF is a feature of aCEF cards (in
cooperation with the Supervisor720/PFC3).  The only aCEF cards are
aCEF720 cards.

> - IPv6-enabled software for 7600 was slideware (not released for the
> public) for about 9 months or more.  I wonder about support for
> sup720 and the features.

Yes, I'd also love to know more about release plans, both for an
IPv6-capable IOS for the Catalyst 6500, and for a version that uses
the PFC3 ASIC for IPv6 forwarding on the Supervisor 720 (may be the
same dates, I don't know).

> - exact IPv6 performance was briefly mentioned only once ("up to 200
> Mpps or so"), it would be nice to get better figures.

The basic idea seems to be that you get ASIC-based forwarding, but
IPv6 forwarding takes two rounds through the ASIC where IPv4 only
takes one.  The main benefit to me is that forwarding speed will be
tightly bounded for IPv6.

An interesting question is whether this continues to be true if you
have IPv6 ACLs.

And whether NetFlow for IPv6 can use the same hardware that does
NetFlow so nicely for IPv4 on the PFC2 (and hopefully even better on
the PFC3).

> - the price differences with previous linecards and new linecards
> (are they expensive or extravagantly expensive)
-- 
Simon Leinen				       simon at babar.switch.ch
SWITCH				   http://www.switch.ch/misc/leinen/

	       Computers hate being anthropomorphized.