Questions on Acct-Interim-Interval

[Alan DeKok]

Vinay Wagh wrote:
> A couple of questions on Acct-Interim-Interval

  These are really questions for the IETF RADIUS standards group.  That
being said, they are partially covered in my document:

http://www.ietf.org/internet-drafts/draft-ietf-radext-fixes-08.txt

  It will be issued as an RFC in a few weeks to months.  Anyone
implementing RADIUS systems *should* read it.  They should also read
my other document:

http://www.ietf.org/internet-drafts/draft-ietf-radext-design-00.txt

  Which discusses protocol design issues.

> 1. I wanted to know if the Acct-Interim update that comes from the NAS has
> any relevance as far as the user session maintained in the radius server is
> concerned. Meaning that is it treated like a keep-alive of some sort. If the
> Acct-Interim-Interval is configured to be 100 seconds and the NAS sends the
> Interim-Update after 200 seconds does the freeradius server care ?

  Many RADIUS servers *will* care.  In some cases, it *is* treated as a
signal that the user session is still alive.

> 2. What is the typical value of this attribute, I ask because if this value
> is configured to be small then it will generate a lot of interim updates
> from a NAS that supports large number of subscribers. At the same time I am
> not sure how the service providers who deploy the server use this Attribute
> and how often do they want the updates.

  See RFC 2869 for recommended values.

  Alan DeKok.