Re: IP CEF

From: Godswill Oletu (oletu@inbox.lv)
Date: Mon Jun 12 2006 - 07:27:03 ART


Petr,

Yes, I normally do that too in my home lab. It does not hurt to turn it ON on all routers. The purpose of my email is actually to address the relationship between CEF and CAR.

Thanks.
Godswill Oletu

  ----- Original Message -----
  From: Petr Lapukhov
  To: Godswill Oletu
  Cc: Sami ; ccielab@groupstudy.com
  Sent: Monday, June 12, 2006 4:00 AM
  Subject: Re: IP CEF

  Thanks Godswill :)

  I did'nt check DocCD before answering, so my memory failed me :)

  Anyway, I still think that turning CEF on every router is not that bad
  idea. As I remember from my lab it has been turned on, when I verified
  my "show adjacencies"

  Petr

  2006/6/12, Godswill Oletu <oletu@inbox.lv>:
    Petr,

>
> AFAIR, CEF is not mandatory for CAR,
>

    Are you sure about that?

    http://www.cisco.com/univercd/cc/td/doc/product/software/ios122/122cgcr/fqos_c/fqcprt1/qcfcar.htm#wp1000872

    The above link referenced and I quote in part:

    "....CAR and DCAR can be configured on an interface or subinterface.
    However, CAR and DCAR are not supported on the Fast EtherChannel, tunnel, or
    PRI interfaces, nor on any interface that does not support Cisco Express
    Forwarding (CEF).

    CEF must be enabled on the interface before you configure CAR or
    DCAR......."

    HTH
    Godswill Oletu

    ----- Original Message -----
    From: "Petr Lapukhov" <petrsoft@gmail.com>
    To: "Sami" < sy1977@gmail.com>
    Cc: <ccielab@groupstudy.com>
    Sent: Sunday, June 11, 2006 3:43 PM
    Subject: Re: IP CEF

> Sami,
>
> it wont hurt to enable CEF anytime, if you are NOT explicitly told
> to disable it :) After all, they have at least 12.3 on every router in
> the lab now :)
>
> AFAIR, CEF is not mandatory for CAR, but it is required for class-based
> marking and NBAR, to mention a few. Some other CEF-dependant things
> are related to load-balancing, and BGP policy accounting, for example :)
>
> Remember the main point of real lab: you could do anything that is
> not restricted by the task conditions, as long as you get the result.
>
> The biggest problem is to figure WHAT is the required result ;) That is,
> you need to pay extremal attention to the wording, and ask for
    clarification
> on every doubtful moment. Next step is to figure how you can verify your
> solution, and the rest is simple :)
>
> Oh yes, and if you have more than one alternative, choose the most simple
> one :)
> The simplest solution is probably always the best.
>
> HTH
> Petr
>
> 2006/6/11, Sami <sy1977@gmail.com>:
> >
> > Group,
> >
> > I am confused when to use IP CEF while doing rate limiting. Is CEF
> > mandatory for CAR or not ?
> >
> > Thanks.
> >
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