[c-nsp] CEF Accounting (was: RE: Risk of enabling ip accounting)

Oliver Boehmer (oboehmer) oboehmer at cisco.com
Mon Oct 29 07:00:26 EDT 2007

Vincent De Keyzer <mailto:vincent at autempspourmoi.be> wrote on Monday,
October 29, 2007 10:35 AM:

> A new hope is suddenly lightening my ignorance: could CEF accounting
> be a solution to my problem? 
> The real-life issue is the following: a VoIP network made of 4948
> switches (doing OSPF and BGP). Those boxes have been selected because
> they would offer good performance even with small (voice) IP packets;
> but their limited memory does not allow to take all the full feeds
> that they are receiving from IP transit providers. So at the moment
> we rely of default routes, which cause the outgoing traffic to be
> very unequally balanced (while incoming traffic is reasonably
> balanced).       
> So I am looking for a method to identify the IP prefixes towards
> which we send most of the traffic, in order to accept only those
> prefixes from our transits (1k routes should be enough - much better
> than 200k+ routes).   
> The application guys do not have an easy answer to this, so I'm
> trying to achieve this at the network level. 
> Is CEF accounting on the current default outgoing interface a
> solution? Again, what is the risk? 
CEF accounting could indeed help you to identify the prefixes you send
most traffic to. Which router platform are you using on your edge
towards the Internet? 


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