DCA Rejects the CCR Message with "is less than last received" Error when CC-Request-Number is Out of Sequence (Doc ID 1549806.1)

Last updated on JULY 01, 2022

Applies to:

Symptoms

The Diameter Control Agent (DCA) rejects the Credit Control Request (Credit-Control-Request or CCR) Update* when the CC-Request-Number is out of sequence.

*Update : the CCR is an Update request if the CC-Request-Type Attribute-Value Pair (AVP) is set to the UPDATE_REQUEST value.

According to the RFC 4006, the application should not reject the request if the CC-Request-Number is unique, but out of sequence.

8.2. CC-Request-Number AVP

The CC-Request-Number AVP (AVP Code 415) is of type Unsigned32 and identifies this request within one session. As Session-Id AVPs are globally unique, the combination of Session-Id and CC-Request-Number AVPs is also globally unique and can be used in matching credit-control messages with confirmations. An easy way to produce unique numbers is to set the value to 0 for a credit-control request of type INITIAL_REQUEST and EVENT_REQUEST and to set the value to 1 for the first UPDATE_REQUEST, to 2 for the second, and so on until the value for TERMINATION_REQUEST is one more than for the last UPDATE_REQUEST.

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and

5.1. General Principles

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5.1.2. Credit-Control for Multiple Services within a (sub-)Session

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Since the client may send CCR messages with the value UPDATE_REQUEST while in PendingU (i.e., without waiting for an answer to ongoing credit re-authorization), the time space between these requests may be very short, and the server may not have received the previous request(s) yet. Therefore, in this situation the server may receive out of sequence requests and SHOULD NOT consider this an error condition. A proper answer is to be returned to each of those requests.

In that case, the following error message may happen as the message is rejected:

Changes

No particular change is linked to this problem. It may happen if the nature of the CC-Request-Number distribution, set by the Gateway GPRS Support Node (GGSN), is changed to introduce disordered CC-Request-Numbers within the same diameter Credit Control session.

The way the NCC (Network Charging and Control) application behaves for disordered CC-Request-Numbers is a function of another AVP, the Multiple-Services-Indicator (set by the GGSN).

Therefore, this problem is more likely to occur due to modification made to the GGSN and not the NCC application.

Cause

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