From: Colin Barber (Colin.Barber@telewest.co.uk)
Date: Sun May 04 2003 - 17:13:55 GMT-3
We are speculating here a bit about the architecture of the 4000. I would
see it as if you are not able to disable CEF then the hardware requires it
to work.
A 6500 may be able to cope with CEF being turned off but it's main processor
is based on a 7500. Even so if you have 100's of Mb of data being
transferred, which is what you would expect in a LAN environment, it will
not cope very well.
Colin
-----Original Message-----
From: Mike Williams [mailto:ccie2be@swbell.net]
Sent: 04 May 2003 18:23
To: 'Charles Church'
Cc: CCIELab@Groupstudy.com
Subject: RE: how to disable "cef" on catalyst 4006?
Chuck,
I don't see why Cisco would make it where you couldn't disable CEF. I
mean, I realize it helps performance, it does have it's share of
problems, and if you CAN'T disable it, then you're screwed if you try to
debug or something at L3. From talking with Nishant, apparently (at
least his version of IOS) doesn't support 'no ip route-cache cef'
interface command, so again, you're out of luck. I surely hope for his
sake this is an IOS bug, as the command is available for him in global
config mode, it just gives an error. But, if there's NO way to disable
CEF, at least per interface if not globally, then that makes me thing
our choice to buy them may have not been the wisest. In all
seriousness, we say stuff like "You could always turn off route-caching,
but with a horrible performance drop" and in theory that is true,
especially on an old 2500 router handling 2 T1s or something, but it
seems that with the CPUs in these 4x00s and 6500s, you'd have to be
really taxing the system good before turning off CEF would knock the CPU
usage up high enough to make it where you HAD to turn CEF back on. Just
my 2 cents.
Mike W.
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Charles Church
Sent: Sunday, May 04, 2003 10:20 AM
To: Nishant Sharma (IT); ccielab@groupstudy.com
Cc: kymblair@hotmail.com
Subject: RE: how to disable "cef" on catalyst 4006?
Nishant,
I don't think disabling CEF is a good solution. The Sup3/4 are
designed hardware-wise around CEF. I don't think any other kind of fast
switching is available on them. You could always turn off
route-caching, but with a horrible performance drop. I'd first try a
newer IOS, since the Sup3 and 4 are pretty new and may have had weird
issues like this with the first couple of code releases. If the newest
one still has the issue, then call TAC. Be sure to check the release
notes for whatever image you want to try, to make sure there isn't a bug
in there that would make your situation worse. HTH.
Chuck Church
CCIE #8776, MCNE, MCSE
Wam!Net Government Services
13665 Dulles Technology Dr. Ste 250
Herndon, VA 20171
Office: 703-480-2569
Cell: 585-233-2706
cchurch@wamnet.com
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of
Nishant Sharma (IT)
Sent: Sunday, May 04, 2003 12:40 AM
To: ccielab@groupstudy.com
Cc: kymblair@hotmail.com
Subject: how to disable "cef" on catalyst 4006?
Dear All,
How do we disable "CEF" on catalyst 4006 coz "no ip cef" command is not
working? When I give this command it gives this error -
Core-I-Switch(config)#no ip cef
%Cannot disable CEF on this platform
Please suggest a solution as this is hindering me to install floating
static routes, ie, even if my primary static route goes down it doesn't
take a static route which I have assigned with a higher AD and when I
issue a "sh ip cef" it still shows me entries for the previous route.
Regards,
Nishant
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