From: Tony Varriale (tvarriale@flamboyaninc.com)
Date: Mon Mar 03 2008 - 03:30:16 ARST
Boy, you guys are something else. I didn't do any attacking. I though it
would be nice not to post incorrect information to a CCIE list as
authoritative.
Maybe I should have unicast him? I will certainly do that in the future. I
apologize in advance to Rik.
Below you will find no more than 5 minutes link searching.
Although it does not answer the poster's question directly, to make everyone
happy:
CEF's general page
http://www.cisco.com/en/US/partner/tech/tk827/tk831/tk102/tsd_technology_sup
port_sub-protocol_home.html
Load balancing with CEF
http://www.cisco.com/en/US/partner/products/hw/modules/ps2033/prod_technical
_reference09186a00800afeb7.html
And I personally recommend
http://www.amazon.com/Inside-Software-Architecture-Professional-Development/
dp/1578701813/ref=sr_1_1?ie=UTF8&s=books&qid=1204521718&sr=8-1
As a side note, I can't wait to meet you guys at Networkers this year. Hope
y'all are going.
Tony
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of Greg
Wendel
Sent: Sunday, March 02, 2008 11:07 PM
To: Tony Varriale
Cc: Rik Guyler; groupstudy groupstudy
Subject: Re: Load balancing
Tony,
Could you be more specific in your criticisms instead of attacking Rik? You
just added to the confusion.
On Sun, Mar 2, 2008 at 11:59 PM, Tony Varriale <tvarriale@flamboyaninc.com>
wrote:
> Any chance you would be able to do some research first and not propagate
> incorrect information regarding CEF? It would certainly help the original
> poster's confusion.
>
> Tony
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
> Rik
> Guyler
> Sent: Sunday, March 02, 2008 10:31 PM
> To: 'Gaurav Prakash'; 'groupstudy groupstudy'
> Subject: RE: Load balancing
>
> If you have CEF (Cisco Express Forwarding) enabled then you are running
> per-destination load balancing. CEF relies on a route cache concept that
> only performs a route table lookup on the first packet of the flow and
> then
> relies on a hardware-based cache for the remainder of the packets. Since
> the lookup only takes place once during the lifecycle of the flow the CPU
> utilization is minimized and the actual packet switching process is much
> faster. This is one of the fast switching paths in Cisco architecture.
>
> In contrast, per packet load balancing, which is called process switching
> (CEF/ip route cache disabled) requires a route table lookup for each
> packet
> so the processor has to work extra hard to do this. The switching
> function
> between interfaces is slower in this mode.
>
> CEF is usually a good thing and typically turned on by default these days.
> Many things require CEF, such as QoS but there are times when you need to
> enable process switching (turn off CEF) such as when you want to run
> certain
> packet debugs. In those cases process switching is the only solution as
> fast switching will not take the packets through the debug process. You
> can
> turn off fast switching globally by typing "no ip cef" or on an interface
> by
> typing "no ip route-cache".
>
> This is just a general explanation for typical devices. Some of the
> higher
> end devices have more options than this.
>
> Rik
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
> Gaurav Prakash
> Sent: Sunday, March 02, 2008 11:01 PM
> To: groupstudy groupstudy
> Subject: Load balancing
>
> Hi,
>
> I have CEF on on my router, I want to be sure which method of load
> balancing will eat more CPU.
>
> Per packet Load balancing or Per Destination Load Balancing
> A brief explanation plz..
>
> Regards,
> Gaurav
>
>
> Save our Earth
>
> ---------------------------------
> Unlimited freedom, unlimited storage. Get it now
>
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