Re: IP cef

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 Fri Feb 08 2013 - 17:34:18 ART