[c-nsp] 6500 SUP720 High Latency and Jitter issues

[Jared Mauch]

On Wed, May 25, 2005 at 11:26:54PM +0200, Gert Doering wrote:
> Hi,
> 
> On Wed, May 25, 2005 at 12:27:26PM -0700, Tim Stevenson wrote:
> > Ah - you can't use the same IP (same loopback) for all your tunnels, you 
> > have to use unqiue IPs to terminate the tunnels.
> 
> I would find it enormously useful if IOS issued a warning if you
> configure something that will be "perfectly fine" on other platforms,
> but will drop the box to software switching on the Sup720...

	I actually disagree with this, this is part of knowing your
platform.  The '76k' (i've renamed it since it's confusing to have the
7600/6500 name, i encourage everyone to call it by this name :) is a software
based platform, with 'mls' hardware assist for some features.  If
you add a distributed linecard, they will be handled in the linecard
(in most cases) that can be seen by doing a 'sh cef line' to know what
slots are likely to be hardware switched.

	This is similar to the 7500, where if you had a VIP linecard,
packets would (if configured for dcef) be handled in a distributed
fashion, but with older linecards, it would be handled on the RP.

> Or, as people have already asked for, a way to figure out "*why* is this
> packet being process switched" - the current output isn't fine-grained
> enough to really know what a box with lots of different features 
> enabled is really doing to *what* packets.

	This is a seperate argument.  Knowing why a platform is doing something
is in part knowing the equipment that you own/operate.  I can understand
some of a learning curve if you acquired someone or got stuck with
some hardware, or make some major changes to your network, but this
is part of the cost of not knowing your hardware.

	Perhaps if vendors are not properly documenting this,
a forum can be created that provides accurate matrix of features
instead of the 'marketing' data that is always touted.. 
A router that can do 10G Full duplex (20G) is different than a router that
can do 10G aggregate.  Accurate feature data, including configlets
may be the solution.  If vendors don't do it, we can do it without them
and that will end up being the honest pressure to get them to document
"unicast-rpf is done in sw on platform X, Y, Z due to limits in the EARL7"
(the above is just a random example, not something that necessarily reflects
facts).

	- Jared

-- 
Jared Mauch  | pgp key available via finger from jared at puck.nether.net
clue++;      | http://puck.nether.net/~jared/  My statements are only mine.