From: Rik Guyler (rik@guyler.net)
Date: Mon Mar 03 2008 - 10:41:47 ARST
Nah, I deserved that. I was trying to lump too many things together to make
a generalized post and didn't communicate it very well. I should know by
now you just can't do that on this list and deserve the criticism. Been too
tired lately to put together much more than random thoughts so totally my
fault.
Rik
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of Tony
Varriale
Sent: Monday, March 03, 2008 12:30 AM
To: 'Greg Wendel'; scott_ccie_list@it-ag.com
Cc: 'groupstudy groupstudy'
Subject: RE: Load balancing
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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-- Gregory Wendel Springfield VA, 22153
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