Dedicated Bearer Establishment without PCRF

Feature Summary and Revision History

Summary Data

Applicable Product(s) or Functional Area

P-GW

Applicable Platform(s)

  • ASR 5500

  • VPC-DI

  • VPC-SI

Feature Default

Disabled - Configuration Required

Related Changes in This Release

Not Applicable

Related Documentation

P-GW Administration Guide

Revision History

Revision Details

Release

First Introduced

Important 
This feature is not fully qualified in this release and is available only for testing purposes. For more information, contact your Cisco Account Representative.

21.16.9

Feature Description

In P-GW, you can create a Dedicated Bearer with the help of local-policy when the Gx connection is down and a specific User Location Information (ULI) set matches during the session in the local-policy along with a configured predefined rule match in the service schema. However, in the StarOS 21.16.9 release, to provide IMS services to the UE that are not VOLTE capable, P-GW uses the deep packet inspection (DPI) functionality to create Dedicated Bearers without interaction with PCRF. This is to maintain high QoS of the voice service although the default bearer gets created with interaction with PCRF for the internet APN.

To detect voice services, SBC IP address (IPv4 or IPv6) and protocol RTP/RTCP is configured in ruledef and a Dedicated Bearer is created when a subscriber traffic matches with the ruledef without interaction with PCRF. If no data flows, then Dedicated Bearer interacts with PCRF over Gx normally and removed after the configured time limit.

How it Works

This section describes call flow and procedure on how the Dedicated Bearer is established without involving PCRF.

Figure 1. Call Flow

This image is not available in preview/cisco.com

Table 1. Procedure

Step

Description

1

Establish Default Bearer with internet APN with PCRF.

2

Default Bearer receives a SIP invite and forwards to SBC.

Note 
SIP invite will be received on port 5060/5061, which is outside the port range for dedicated bearer.

3

An RTCP packet is received matching the SBC address and port-range that matches to the trigger rule.

4

A dedicated bearer is created with predefined Audio_dedicated_rule and TFT with multiple ranges of port as defined by packet-filters tft1 and tft2.

Note 
The charging-action for such rule should have billing-action egcdr and content-id configured.

5

UE pushes any packets for the specified port ranges to the dedicated bearer and matches with the Audio_dedicated_rule.

6

After 300 seconds, or configured timeout value of inactivity, and according to the threshold configuration, the Bearer is deleted and P-GWCDR gets generated for a Bearer with corresponding data counts.

  • You can adjust the threshold based on the keep-alive/watchdog messages.

  • The SIP control messages after voice call flows on the ports that are outside the port-range defined for Dedicated Bearer TFT.

    Note 
    As SIP control messages are sent by UE on the Default Bearer, it will not be considered under Dedicated Bearer activity.

Configuring active-charging-services

Use the following example configuration to establish a dedicated bearer without interaction with PCRF.

configure
  active-charging service acs
    ruledef Audio_dedicated_rule
      ip dst-address = 1.1.1.1/32
    #exit
    ruledef trigger_rule
      ip dst-address = 1.1.1.1/32
      udp either-port range 1024 to 5059
      udp either-port range 5062 to 43672
    #exit
    packet-filter tft1
      ip remote-port range 1024 to 5059
      ip remote-address = 1.1.1.1/32
    #exit
    packet-filter tft2
      ip remote-port range 5062 to 43672
      ip remote-address = 1.1.1.1/32
    #exit
    charging-action no_charge
    #exit	
    charging-action ca_audio
      content-id 2
      billing-action egcdr
      qos-class-identifier 1
      flow limit-for-bandwidth direction downlink peak-data-rate 256000 peak-burst-size 32000 violate-action discard
      flow limit-for-bandwidth direction uplink peak-data-rate 256000 peak-burst-size 300000 violate-action discard
      allocation-retention-priority 4 pvi 1 pci 1
      tft packet-filter tft1
      tft packet-filter tft2
    #exit
    rulebase prepaid
       billing-records egcdr
	#Install Audio_dedicated_rule on dedicated bearer to cater to VoLTE traffic
      action priority 1 dynamic-only ruledef Audio_dedicated_rule charging-action ca_audio
	#Use traffic matching to trigger_rule on default bearer as trigger condition
      action priority 2 ruledef trigger_rule charging-action no_charge
    #exit
    trigger-action TA1
      activate-predef-rule Audio_dedicated_rule
    #exit
    trigger-condition TC1
      rule-name = trigger_rule
    #exit
    trigger-condition tc
      rulebase = prepaid
    #exit
    service-scheme SS
      trigger flow-create 
        priority 1 trigger-condition TC1 trigger-action TA1 
      #exit
    subs-class SC1
      rulebase = prepaid
    #exit
    subscriber-base sb
      priority 1 subs-class SC1 bind service-scheme SS
    #exit
  #exit
  context egress
    apn internet
	#Remove dedicated bearer after 300 seconds of inactivity
      timeout bearer-inactivity gbr 300 volume-threshold total 1 
	active-charging rulebase prepaid
    exit
  exit
end