Subject: COPS - Query PEP for policy detail?

From: [email-masked]
Date: Tue, 6 Feb 2001 15:23:52 -0600

Hi,

In SNMP, we may use "get" to query the values of attributes on PEP. It seems
to me that we cannot do the same thing with COPS and COPS-PR. For example,
can a PDP ask a PEP to send back its current policy in PIB format (PRID +
data)? 

Comments are appreciated.

Man Li
Nokia 
5 Wayside Road, Burlington, MA 01803
[email-masked]
phone 1-781-993-3923
GSM 1-781-492-2850

---

From: "Durham, David" <[email-masked]>
Date: Wed, 7 Feb 2001 09:20:53 -0800

> -----Original Message-----
> From: [email-masked] [mailto:[email-masked]]
> 

[Dave] Well, COPS was optimized to do device provisioning/configuration and
event-driven accounting, where SNMP is better at polling and getting data
from a device. PIBs are algorithmically convertible to MIBs so that you can
use SNMP to actually "get" the policies installed on a device (SNMP should
already be on the device anyway). 

If one wanted to do it all with COPS, that's possible too. All you would
need is a PIB PRC called "resynch" (or whatever you like) that the PDP can
update (via DEC message). When the PDP wants to get a policy or all policies
on a device, it can simply trigger the PEP's resynch variable, which would
cause the PEP to send select policies via a Report message. No such standard
resynch PIB exists today, however.

-Dave

---

From: "Durham, David" <[email-masked]>
Date: Wed, 7 Feb 2001 17:38:59 -0800

> > The PEP policy is controlled and installed/removed by the 
> > PDP. I don't see a
> > lot of value for the PDP "getting" the policy it installed back.
> >
> 
> One benefit of this ability could be to add more value to 
> synchronization.
> Current Synchronization mechanism leaves a lot to be desired. 
> essentially it
> will just repeat past request that PEP had sent. this does 
> not tell PDP
> much. however ability to get list of installed policies could 
> actually tell
> PDP that even though it had sent policies p1 thru p11 to the 
> PEP, PEP is
> only reporting presence of p1 thru p9. It could also aid backup PDP in
> determining what policies were downloaded by primary PDP 
> before it went
> down.
> 
[Dave] Actually, the Framework PIB provides a Policy ID variable (in the
incarnation table) from the last policy exchange. This is repeated back from
the PEP to the PDP after a connection failure during the subsequent
reconnect & COPS resynchronization procedure. From this incarnation value
communicated via the subsequent Request message, the PDP will be able to
figure out what state the PEP is in. Reducing this state keeping to a single
value is more efficient than repeating back the whole list of currently
installed policies, and achieves the desired result as well.

---

From: "Iliff, Tina" <[email-masked]>
Date: Thu, 08 Feb 2001 14:45:40 +0000

I agree with David.  The capability is there and the "how to use it" is just
an implementation issue.  The PibIncarnationId value can also be useful in a
couple of other areas as well.

Tina Iliff