From: Koen Zeilstra (koen@koenzeilstra.com)
Date: Thu May 18 2006 - 03:36:17 ART
Ok to summarise all the answers I received (thanks for that!):
When you have to use CEF for limiting traffic: use CAR
When you are not allowed to use CEF for limiting traffic: use police with
ACL
Otherwise always enable ip cef.
-----------------------
"I'm prepared for all emergencies but totally unprepared for everyday
life."
On Thu, 18 May 2006, Emir trhulj wrote:
| Hello,
| Accoding to the Doco
|
| "*Note *CAR and DCAR can only be used with IP traffic. Non-IP traffic is not
| rate limited.
|
| 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.
|
| CAR is not supported for Internetwork Packet Exchange (IPX) packets."
|
| I would use an ACL to match the traffic and then use MQC if I was not
| allowed to use CEF.
|
| Emir
|
|
| On 5/18/06, Koen Zeilstra <koen@koenzeilstra.com> wrote:
| >
| > In a workbook a task was mentioned to rate limit traffic at a certain
| > amount and don't use cef. The solution was a police based method using
| > MQC. So they didn't use rate limiting. I read that as since rate limiting
| > relies on CEF. Not sure if this is true.
| >
| > It would defenately help if someone pointed to a valid source which
| > clearly states:
| >
| > no ip cef for QOS --> don't use blah di blah
| > use ip cef for QOS --> use blah di blah
| >
| >
| > -----------------------
| > A fool must now and then be right by chance.
| >
| > On Wed, 17 May 2006, Roberto Fernandez wrote:
| >
| > |
| > | I think it is restricting you to NOT use NBAR, just that. MQC itself
| > | does not requires CEF, not CAR either requires it. (I understand)
| > |
| > | Best Regards,
| > | Roberto
| > |
| > | -----Original Message-----
| > | From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
| > | Koen Zeilstra
| > | Sent: Wednesday, May 17, 2006 2:02 PM
| > | To: Daniel Kutchin
| > | Cc: ccielab@groupstudy.com
| > | Subject: Re: CEF and QoS, again
| > |
| > | In other words (forget my previous email):
| > |
| > | When the QOS task requires you to "not use cef" what options do you have
| > |
| > | left?
| > |
| > | And what about restricting to use cef for your solution?
| > |
| > | grtz,
| > |
| > | Koen
| > |
| > | -----------------------
| > | unix soit qui mal y pense
| > |
| > | On Tue, 16 May 2006, Daniel Kutchin wrote:
| > |
| > | | Hi Taylor -
| > | |
| > | | 4) Disable CEF for PPPoFR (i.e. Virtual Templates)
| > | |
| > | | BTW: Always enable CEF in order to use NBAR (In the book according to
| > | Odom
| > | | Chapter p.222)
| > | |
| > | | Daniel
| > | |
| > | | ----- Original Message -----
| > | | From: "Wang, Ting (Taylor)" <wangting@avaya.com>
| > | | To: <ccielab@groupstudy.com>
| > | | Sent: Sunday, May 14, 2006 4:09 AM
| > | | Subject: RE: CEF and QoS, again
| > | |
| > | |
| > | | Hi Group,
| > | | Sorry missed the text in last mail.
| > | | I find some discussion on when CEF need to be enabled for QoS, but
| > | | still not quite sure. From previous discussion, it concludes that CEF
| > | | need to be enabled when you are using NBAR, marking your traffic or
| > | | CAR. Is that correct? For marking, there is several appoach like
| > | police,
| > | | MQC set, PBR, and CAR. In which case the CEF is a must, and in which
| > | | case it is recommended or not required?
| > | | There is another saying "you don't have to enable NBAR to mark traffic
| > | | via protocol (for well-known protocols at least)." " CEF and QoS are
| > | | mutually exclusive." How to understand it? In which case we need to
| > | | disable the CEF for QOS?
| > | | Following are conclusion from some past discussion, any idea on that?
| > | | 1) There are no real reasons that you want to disable CEF unless you
| > | | were running into a bug where's it causing problems.
| > | | 2) Disable CEF when using proxy-arp, 'cause this can cause a routing
| > | | loop
| > | | 3) If you wanted to load-balance by the routing protocol then you
| > | would
| > | | not want cef . The logic being that cef would assume the load
| > | balancing
| > | | functions over the routing protocol once populated.
| > | |
| > | | Thanks,
| > | | Taylor
| > | |
| > | |
| > | _______________________________________________________________________
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| > |
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| > |
| > |
| > |
| >
| > _______________________________________________________________________
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