Cisco Cisco ASR 5000 Guide De Dépannage

ASR5500 Series Default Policy Is Not Handed Out
When PCRF Is Down

Document ID: 119201

Contributed by Abdur Razzaque, Cisco TAC Engineer.

Jul 23, 2015

Contents

Introduction
Problem
Solution
Related Information

Introduction

This document describes how to handle the default local policy in the Cisco Aggregation Services Router
(ASR) 5500 chassis, in the event of PCRF (Policy Control and Rule Function) failure, when the local default
policy is not configured.

Problem

The ASR PGW (Packet Data Gateway) failed to handle the default policy for subscribers when PCRF was
down. In the PCRF upgrade phase, issues were observed on the PCRF. However, the ASR PGW failed to
handle the default policy for subscribers which caused many sessions to be dropped.

Wireshark traces indicate that all CCA−I (Credit Control Answer Initial) packets are sent from PCRF with the
Diameter Result−Code "DIAMETER_UNKNOWN_SESSION_ID (5002)" during the incident.

A sample packet is shown here:

2014−10−01 06:20:00.009092 107.72.199.142 172.18.232.142 DIAMETER 286

[TCP Retransmission] cmd=Credit−ControlAnswer(272) flags=−P−− appl=3GPP

Gx(16777238) h2h=70409850 e2e=4a67829

AVP: CC−Request−Type(416) l=12 f=−M− val=INITIAL_REQUEST (1)

AVP: Result−Code(268) l=12 f=−M− val=DIAMETER_UNKNOWN_SESSION_ID (5002)

From configuration, the ASR does not have the Local Policy fallback configured to 5002 (or 5xxx) codes in
order to perform Failure Handling (FH) for such codes:

failure−handling−template FHtemplate

msg−type credit−control−initial failure−type diameter result−code 3000 to 3999

action continue local−fallback

msg−type credit−control−initial failure−type tx−expiry action continue local−fallback

msg−type credit−control−initial failure−type resp−timeout action continue

local−fallback

msg−type credit−control−initial failure−type diabase−error action continue

local−fallback

msg−type credit−control−update failure−type diameter result−code 3000 to 3999 action

continue local−fallback

msg−type credit−control−update failure−type tx−expiry action continue local−fallback