[c-nsp] Troubleshooting Lag between GigE interfaces

[Rodney Dunn]

It's only for traffic to/from that slot.

But if you want to do a lot of features (ie: QOS,
MLPPP, etc.) then you must have dCEF or we don't support
it.

Why is that?

Because as this box has transitioned from a centralized
forwarding box to a distributed forwarding box we have
tried very hard to support all permutations of switching
paths.

It reaches a point where you can't and that's why
are you are now seeing that "feature X" is only supported
with dCEF.

That's why for example on the GSR it's distributed or nothing.
It was designed with that in mind.

When the 75xx was first developed distributed meant between
boxes. :)

My advice to customers is you do it one of two ways:

a) Get an RSP fast enough to run in centralized CEF mode
or
b) Make sure all your cards are dCEF capable and have
   the CPU power to handle the features and run in dCEF mode.


If I have an RSP that can do features at X rate which
is more than the cards can do at Y rate I'm better off
in centralized RSP mode.  If the VIPs can do the work
distributed much faster than I can do it centrally then
I should go with dCEF mode.

I see the most problems when customers try to run it
in some hybrid mode.


Rodney



On Thu, Sep 23, 2004 at 07:11:36PM +0200, Daniel Roesen wrote:
> On Thu, Sep 23, 2004 at 12:22:34PM -0400, Rodney Dunn wrote:
> > One other thing, if anyone ever wants to run dCEF on a 75xx
> > they should make sure ALL cards support it and that means
> > getting rid of the old legacy ip boards (ie: FSIP).
> > You need to get a VIP/serial PA combination for those links.
> 
> But this does only affect traffic switched FROM such legacy interface
> to other slots, correct? an FSIP in a 7500 wouldn affect dCEF working
> for traffic switched between two VIP slots?!
> 
> 
> Best regards,
> Daniel
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