[cisco-bba] PPPoE and per subscriber rate/bandwidth limiting

Andy Schutz (aschutz) aschutz at cisco.com
Mon Feb 2 16:42:35 EST 2004


I'm not sure what is most common, probably ATM shaping but there is
certainly a lot using IP based policing handed down via an av-pair from
RADIUS.  I can't speak to the scaling/performance of the Redback SMS
products but on a Cisco platform you shouldn't have any issues policing
traffic regardless of the rate configured on the policer.  Of course,
you need to be mindful of CPU and memory usage when terminating large
numbers of subscribers on CPU based platforms like the 7200 for example.
On the Cisco 10000, since the policing function is carried out inline
with packet processing and not CPU based, there is no impact on
performance (packets per second) when doing policing.  In both cases,
the accuracy of the policer shouldn't be influenced by the policer rate.
As you mentioned, the IP based policing applies in both the ATM PVC or
Ethernet scenarios.

Hope that helps,


> -----Original Message-----
> From: cisco-bba-bounces at puck.nether.net 
> [mailto:cisco-bba-bounces at puck.nether.net] On Behalf Of Eric Helm
> Sent: Monday, February 02, 2004 3:24 PM
> To: cisco-bba at puck.nether.net
> Subject: [cisco-bba] PPPoE and per subscriber rate/bandwidth limiting
> Hello,
> We are a small ISP and currently we are using a Redback SMS 
> to terminate 
> PPPoE sessions. I am curious, what is the most common way to 
> perform per 
> sub rate-limiting? Is it at the ATM level on individual PVCs? Or by 
> passing RADIUS attributes to the ppp session? If you are 
> doing it on a 
> PVC level, how do you handle Ethernet uplinks like say a 
> wireless access 
> system?
> We are using RADIUS currently, and seeing some performance 
> problems with 
> higher rate profiles like 512Kb and above. I am looking for 
> some other 
> method of doing the rate limiting, except we have about 40% of our 
> broadband subscribers with wireless access and ethernet back to the 
> core. So setting limits per PVC is not an option for these subs.
> Thanks for any input.
> -Eric
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