Subject: [Ips] Valid Negotiation

From: <[email-masked]>
Date: Thu, 19 Mar 2009 15:29:02 -0500

I   ->  T :   DefaultTime2Retain=2
T  ->  I  :   DefaultTime2Retain=5
I  ->  T  :   DefaultTime2Retain=5

Is this valid?

---

From: Ken Sandars <[email-masked]>
Date: Fri, 20 Mar 2009 11:44:14 +1100

This sequence is invalid and both parties have issues.

DefaultTime2Retain uses the Minimum function for negotiation,
has admissible values 0..3600 and the default is 20 (RFC3720
section 12.16). The initiator's proposal is valid.

The target MUST answer with a value in the range 0..2 since
the proposed value is admissible (also refer RFC3720 section
5.2.2). Hence the answer outside this range is a protocol error.
Alternatively it had the option to use "Reject" if it really wanted
a value outside the proposed range. In that case the default
value (20) becomes the negotiated value.

The initiator is also in error. It should not have re-issued the
KVP. One could wonder as to why it was only willing to accept
a maximum of 2 seconds in its offer but is now happy to use
5 seconds! The correct action is to terminate the login since
the target's response is a protocol error.

Cheers,
Ken
Date: Thu, 19 Mar 2009 15:29:02 -0500
From: [email-masked]
To: [email-masked]
Subject: [Ips] Valid Negotiation

Valid Negotiation

Is this valid?

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