Re: IP cef

Thanks all for a good discussion. another question on ip cef is that when I
enable <ip cef distributed> and <ip routing>, I don't see ip cef in output
of <sh run> or <show run all> on 3550 / 3650 / 3760 switching platforms. I
know that ip cef is running on these platforms by default as soon as I
enable ip routing. Is there any way of disabling ip cef on switches?

Kind regards

On 9 February 2013 01:34, marc edwards <renorider_at_gmail.com> wrote:

> Thanks for clarifying Marco. I'm a little red in the face making that
> mistake.
>
> On Fri, Feb 8, 2013 at 4:53 PM, David Prall <dcp_at_dcptech.com> wrote:
> > After the MFI rewrite there is no Fast Path, you get either CEF or
> Process Switching. So 12.4(20)T and beyond are hard pressed to run without
> "ip cef" enabled.
> >
> > --
> > http://dcp.dcptech.com
> >
> >
> >> -----Original Message-----
> >> From: nobody_at_groupstudy.com [mailto:nobody_at_groupstudy.com] On
> >> Behalf Of Marko Milivojevic
> >> Sent: Friday, February 08, 2013 7:43 PM
> >> To: marc edwards
> >> Cc: Keller Giacomarro; Mohammad Mousa; Tauseef Khan; Cisco certification
> >> Subject: Re: IP cef
> >>
> >> MPLS control plane does not require CEF. It's the MPLS forwarding
> >> plane that requires it. It makes up for an interesting troubleshooting
> >> :-).
> >>
> >> Things change between IOS versions and behave differently on different
> >> platforms, but I recall that uRPF also needed CEF to work. I'm
> >> positive that ZBF needs it, as well (never tried it with CEF off
> >> though - feel free). On switches for example, you cannot turn CEF off
> >> if you have "ip routing" enabled, as it requires CEF to work.
> >>
> >> --
> >> Marko Milivojevic - CCIE #18427 (SP R&S)
> >> Senior CCIE Instructor / Managing Partner - IPexpert
> >>
> >> On Fri, Feb 8, 2013 at 4:36 PM, marc edwards <renorider_at_gmail.com>
> wrote:
> >> > Marko,
> >> >
> >> > Thanks for chiming in. I am interested to know what other control
> >> > protocols on blue print rely on CEF aside from MPLS?
> >> >
> >> > Marc
> >> >
> >> > On Fri, Feb 8, 2013 at 3:39 PM, Marko Milivojevic <
> markom_at_ipexpert.com>
> >> wrote:
> >> >> What if "ip routing" was disabled on routers? How about if escape
> >> >> character was set to "space", etc? Paranoia, or "I'll always do this
> >> >> in a case they're playing games" will not get you very far in the lab
> >> >> :-).
> >> >>
> >> >> I recommend you do what's needed, no less, no more. If CEF is turned
> >> >> off, turn it on if you need it, otherwise, why do you care if it was
> >> >> turned off? :-)
> >> >>
> >> >> --
> >> >> Marko Milivojevic - CCIE #18427 (SP R&S)
> >> >> Senior CCIE Instructor / Managing Partner - IPexpert
> >> >>
> >> >> On Fri, Feb 8, 2013 at 1:30 PM, Keller Giacomarro <
> keller.g_at_gmail.com>
> >> wrote:
> >> >>> I have a pre-defined set of commands I run on all my configuration-
> >> section
> >> >>> devices before I start the section.
> >> >>>
> >> >>> ***
> >> >>> ip cef (doesn't work on switches without 'ip routing' enabled)
> >> >>> ip classless
> >> >>> ip subnet-zero
> >> >>> ***
> >> >>>
> >> >>> My logic is -- If any of these are disabled, it's most likely going
> to be a
> >> >>> purposeful 'break' that you have to fix. If they want them to stay
> >> >>> disabled, they'll tell you in the questions. Either way, it
> doesn't hurt
> >> >>> you to run all three by default on all devices.
> >> >>>
> >> >>> One that I DON'T run is 'ip routing'. It's not a given that all
> switches
> >> >>> will be running routing protocols, and when you enable IP routing it
> >> >>> disables the default-gateway, which means adding a static route.
> This is
> >> >>> probably not allowed in your lab.
> >> >>>
> >> >>> I have another tip for the troubleshooting section. I put this
> text into
> >> >>> notepad and copy-paste it into every device I open as I open them.
> >> >>>
> >> >>> ***
> >> >>> conf t
> >> >>> logging con debug
> >> >>> end
> >> >>> copy running-config nvram:original.cfg
> >> >>>
> >> >>> n
> >> >>>
> >> >>>
> >> >>> ***
> >> >>>
> >> >>> First, this ensures I can see all logging outputs. If it's the
> first time
> >> >>> I've accessed the device, the config is backed up to
> nvram:original.cfg,
> >> >>> and the 'n' will be an invalid command. If it's NOT the first time
> I've
> >> >>> accessed the device, the newline and the n means original.cfg will
> NOT
> >> get
> >> >>> overwritten (answers 'no' to 'do you want to overwrite'). I save to
> >> nvram:
> >> >>> instead of flash: just in case their IOU instances do not have a
> flash --
> >> >>> all devices have nvram.
> >> >>>
> >> >>> A quick 'end' and then 'wr' before I close ANY window ensures that
> all
> >> my
> >> >>> work gets saved too.
> >> >>>
> >> >>> This works great for me, what is your strategy?
> >> >>>
> >> >>> Keller Giacomarro
> >> >>> keller.g_at_gmail.com
> >> >>>
> >> >>>
> >> >>> On Fri, Feb 8, 2013 at 11:34 AM, marc edwards <renorider_at_gmail.com>
> >> wrote:
> >> >>>
> >> >>>> I can think of at least one control protocol on the blueprint that
> >> >>>> won't work w/out CEF (MPLS). Can anyone else add to the list?
> >> >>>>
> >> >>>> Marc
> >> >>>>
> >> >>>> On Fri, Feb 8, 2013 at 8:03 AM, Mohammad Mousa <mohd-
> >> mousa_at_hotmail.com>
> >> >>>> wrote:
> >> >>>> > Tauseef,
> >> >>>> >
> >> >>>> > I think you've to enable them, because some of the services won't
> >> work
> >> >>>> well unless you enable IP CEF/IPV6 CEF, and I think you won't get
> the
> >> >>>> complete mark unless you put these commands.
> >> >>>> >
> >> >>>> > HTH,
> >> >>>> >
> >> >>>> > -Mohammad Mousa
> >> >>>> > CCIE #36990
> >> >>>> >
> >> >>>> >> Date: Fri, 8 Feb 2013 15:33:50 +0000
> >> >>>> >> Subject: IP cef
> >> >>>> >> From: tasneemjan_at_googlemail.com
> >> >>>> >> To: ccielab_at_groupstudy.com
> >> >>>> >>
> >> >>>> >> If in the lab ip cef is disabled on the routers and I enable ip
> cef /
> >> >>>> ipv6
> >> >>>> >> cef on routers, will I lose marks for that, as over
> configuration.
> >> >>>> Without
> >> >>>> >> ip cef every thing will be process switched but still all the
> routing
> >> >>>> will
> >> >>>> >> work as normal. Appreciate if someone could explain?
> >> >>>> >> Regards
> >> >>>> >>
> >> >>>> >>
> >> >>>> >> Blogs and organic groups at http://www.ccie.net
> >> >>>> >>
> >> >>>> >>
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Received on Tue Feb 12 2013 - 17:06:08 ART