Cisco Cisco ASR 5500 トラブルシューティングガイド
Offload SGSN Subscribers with Target−NRI and
Target−Count in the SGSN Pool for an ASR 5000
Series
Target−Count in the SGSN Pool for an ASR 5000
Series
Document ID: 118941
Contributed by Krishna Kishore D V, Cisco TAC Engineer.
May 12, 2015
May 12, 2015
Contents
Introduction
Background Information
Offload Subscribers in Target SGSN
Basic Configuration Required
Technical Justification and Explanation
Signal Transfer Point Link Congestion Prevention
Analysis
Offloading Algorithm for Target Count
Global Configuration for Offloading Based on Target−Count
Offloading Phase 1
Offloading Phase 3
Stop Offloading and Remove STP Congestion Protection Command
Important Notes
Background Information
Offload Subscribers in Target SGSN
Basic Configuration Required
Technical Justification and Explanation
Signal Transfer Point Link Congestion Prevention
Analysis
Offloading Algorithm for Target Count
Global Configuration for Offloading Based on Target−Count
Offloading Phase 1
Offloading Phase 3
Stop Offloading and Remove STP Congestion Protection Command
Important Notes
Introduction
This document describes how to offload traffic from one Serving General Packet Radio Service (GPRS)
Support Node (SGSN) to Another SGSN in the same pool with the use of a target−Network Resource
Identifier (NRI).
Support Node (SGSN) to Another SGSN in the same pool with the use of a target−Network Resource
Identifier (NRI).
Background Information
In order for the Cisco 500 Series Aggregation Services Router (ASR500) SGSN to offload subscribers, it
assigns a Non Broadcasting−Routing Area Identifier (NB−RAI), stamps a target−NRI in the Packet
Temporary Mobile Subscriber Identifier (P−TMSI), and reduces the periodic routing area update timer during
the Attach/Routing Area Update (RAU) accept messages. The offload CLI command is enhanced with the
target−NRI and the number of subscribers in order to offload with that target−NRI. Once the target−based
offloading CLI command is issued, the SGSN begins to offload the subscribers. It does not stop the offload
process until a disable CLI command is issued, or when the target−count is reached.
assigns a Non Broadcasting−Routing Area Identifier (NB−RAI), stamps a target−NRI in the Packet
Temporary Mobile Subscriber Identifier (P−TMSI), and reduces the periodic routing area update timer during
the Attach/Routing Area Update (RAU) accept messages. The offload CLI command is enhanced with the
target−NRI and the number of subscribers in order to offload with that target−NRI. Once the target−based
offloading CLI command is issued, the SGSN begins to offload the subscribers. It does not stop the offload
process until a disable CLI command is issued, or when the target−count is reached.
Here is some important information to consider about the offload process:
The SGSN does not have control over the offload rate; it depends on the Attach/RAU requests from
the subscribers. The Attach/RAU requests can occur for current or new subscribers, and the current
subscribers can be in either the Idle/Connected or Standby/Ready state.
the subscribers. The Attach/RAU requests can occur for current or new subscribers, and the current
subscribers can be in either the Idle/Connected or Standby/Ready state.
•
Because the Attach/RAU requests are not controlled by the SGSN, the SGSN cannot commit
rate/counts per Session Manager (SESSMGR).
rate/counts per Session Manager (SESSMGR).
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