Configure CSFB to Activate in Cisco ASR5x00 Series MME

Introduction

This document describes how to implement the change(s) specified for Circuit Switch Fall Back (CSFB) activation in order to allow the voice and Short Messaging Service (SMS) with Mobile Switching Center (MSC)/Visitor Location Registry (VLR) over a subscriber group (SG) interface. The SG interface is between Mobility Management Entity (MME) in the Evolved Packet System (EPS) and the VLR, in order to allow location management coordination and in order to relay certain messages related to circuit switched services over the EPS system.

This is implemented on a MME deployed on Cisco Aggregated Service Router (ASR) 5x00 series (ASR5x00).

Prerequisites

Requirements

Ensure that you have Show Support Details (SSDs), bulkstat files, syslog files and any additional CLI output as required for the identified ASR5x00 nodes.

Components Used

This document is not restricted to specific software and hardware versions.

The information in this document was created from the devices in a specific lab environment. All of the devices used in this document started with a cleared (default) configuration. If your network is live, make sure that you understand the potential impact of any command.

Background Information

What is CSFB?

CSFB allows 3G/4G capable User Equipment (UE) to fallback to the 3G network for circuit switch functions, supports SMS, and voice calls.

References

• 3rd Generation Partnership Project (3GPP) Technical Specfications (TS) 23.272: Circuit Switch (CS) fallback in EPS

• 3GPP TS 29.118: SG interface specification

This diagram is based upon SGs that use Steam Control Tranmission Protocol (SCTP) for transport:

Mobile Originating Call (PS Handover)

Mobile Originating Call (PS Suspension)

Mobile Terminating Call (Idle Mode)

Mobile Terminating Call (PS Handover)

3G-to-4G Reversion

• UE Decides
• If Packet Switch (PS) Hand-over (HO) occurred, reversion is normal 3G-to-4G HO
• If PS Suspension occurred, network recovers suspended bearers for UE that returns

Mobile Call (PS Resumption)

Configure

Note: Use the Command Lookup Tool (registered customers only) in order to obtain more information on the commands used in this section.

Pre-Activation Health Check

Collect the output of these commands:

show configuration

show crash list

show alarm all

show snmp trap history

show configuration errors

show logs

show card table

show card hardware

show subscribers summary

show leds all

show port utilization table

show linecard table

show card mapping

show session progress

show threshold

show ntp associations

show cpu table

show ntp status

show system uptime

show clock

show license information

show task resource

show ip interface summary


Repeat below steps over all context

Context <context_name>

show ip interface summary

show ip route


show egtp-service all

show egtpc statistics

show session disconnect-reasons

show mme-service all 

show mme-service enode-association all

show hss-peer-service service all

show diameter peers full

show sgs-service all

show sgs-service vlr-status full

Logs checkpoint

clear snmp trap history

Pre-Activation Procedure

1. Save the current configuration to the Flash drive for backup.
2. Use the Naming conventions as per Operator Nomenclature:

   [local] #save configuration /flash/Config_Date_before_activity.cfg -r -no

3. Enter the show support details command in order to see the details of the chassis:

   [local] #show support details

4. Enter the show boot command in order to confirm the existing boot order:

   [local] #show boot
   
   
   	boot system priority 7 \
   
   	image /flash/production.37140.st40.bin \
   
   	config /flash/QGLC-final-25-08-11.cfg
   
   
   	boot system priority 8 \
   
   	image /flash/production.37140.st40.bin \
   
   	config /flash/config_g101.cfg
   
   
   	boot system priority 9 \
   
   	image /flash/production.34838.st40.bin \
   
   	config /flash/config_g101.cfg
   
   
   	boot system priority 10 \
   
   	image /flash/st40.bin \
   
   	config /flash/system.cfg

5. Enter the show license information command in order to confirm the installed CSFB license on the chassis:

   [local] #show license information
   
   
   	Key Information (installed key):
   
   	Comment        MME/SGSN 1 SO:50931561,51138669
   
   	Device 1      Model:         "VICF4GB"
   
   		      Serial Number: "VICF4GB00000B7B"
   
   	Device 2      Model:         "VICF4GB"
   
   		     Serial Number: "VICF4GB00000C0D"
   
   	Issued        Monday November 28 12:05:59 EST 2014
   
   	Issued By     Cisco Systems
   
   	Key Number    48086
   
       Enabled Features:
   
   	Feature                       Applicable Part Numbers
   
   	----------------------------  -----------------------------
   
   	IPv4 Routing Protocols        [ none ]
   
   	IPv6                          [ N/A / N/A ]
   
   	Lawful Intercept              [ ASR5K-00-CSXXLI ]
   
   	RADIUS AAA Server Groups      [ ASR5K-00-CSXXAAA ]
   
   	SGSN Software License         [ ASR5K-00-SN10SESS / ASR5K-00-SN01SESS ]
   
   	MME license:                  [ ASR5K-00-ME01BASE / ASR5K-00-ME10LIC ]
   
   	+ Session Recovery           [ ASR5K-00-PN01REC / ASR5K-00-HA01REC
   
   		                     ASR5K-00-00000000 / ASR5K-00-GN01REC
   
   		                     ASR5K-00-SN01REC / ASR5K-00-AN01REC
   
   		                     ASR5K-00-IS10PXY / ASR5K-00-IS01PXY
   
   		                     ASR5K-00-HWXXSREC / ASR5K-00-PW01REC
   
   		                     ASR5K-05-PHXXSREC / ASR5K-00-SY01R-K9
   
   		                     ASR5K-00-IG01REC / ASR5K-00-PC10SR
   
   		                     ASR5K-00-EG01SR / ASR5K-00-FY01SR
   
   		                     ASR5K-00-CS01LASR / ASR5K-00-FY01USR ]
   
   	 + Enhanced Lawful Intercept  [ ASR5K-00-CS01ELI / ASR5K-00-CS10ELI ]
   
   	  APN Aliasing                  [ ASR5K-00-SNXXALES ]
   
   	  Circuit Switched Fallback     [ ASR5K-00-CS01CSFB ]
   
   	  Always On Licensing           [ ASR5K-00-GNXXAOL ]
   
   	  Session Limits:
   
   		      Sessions  Session Type
   
   		      --------  -----------------------
   
   		      610000  MME license
   
             CARD License Counts:
   
   	  [none]
   
   	  Status:
   
   	     Device 1               Matches card 8 flash
   
   	     Device 2               Matches card 9 flash
   
   	     License Status         Good (Redundant)
   
   

CSFB Activation Procedure

1. Configure the SG interface with the given IP address.
2. Configure the SG service with the Stream Control Transmission Protocol (SCTP) port number, Tracking Area Code (TAC) to Location Area Code (LAC) mapping, pool area, and so forth.
3. Bind the interface IP address to the SG service and associate a SCTP template if any:

   [local]#config
   
   [local](config)#context mme
   
   [mme](config-ctx)#interface sgs
   
   [mme](config-if-eth)#ip address xxx.xxx.xxx.xxx 255.255.255.xxx
   
   [mme](config-if-eth)#exit
   
   [mme](config-ctx)#sgs-service sgs_svc
   
   [mme](config-sgs-service)#sctp port xxxx
   
   [mme](config-sgs-service)#tac-to-lac-mapping any-tac map-to lac xxx
   
   [mme](config-sgs-service)#vlr VLR1 ipv4 xxx.xxx.xxx.xxx 
              ipv4-address xxx.xxx.xxx.xxx port xxx
   
   [mme](config-sgs-service)#pool-area east_nodes
   
   [mme](config-sgs-pool-area)#lac xxx
   
   [mme](config-sgs-pool-area)#hash-value non-configured-values use-vlr VLR1
   
   [mme](config-sgs-pool-area)#exit
   
   [mme](config-sgs-service)#bind ipv4 xxx.xxx.xxx.xxx
   
   [mme](config-sgs-service)#associate sctp-param-template sgs_svc
   
   [mme](config-sgs-service)#exit

4. Associate the SG service name with MME service:

   [mme](config-ctx)#mme-service mme_svc
   
   [mme](config-mme-service)#associate sgs-service sgs_svc context mme
   
   [mme](config-mme -service)#end

5. Configure the Virtual LAN (VLAN) for the SG interface and bind to the respective context name:

   [local]#config
   
   [local](config)#port ethernet 17/1
   
   [local](config-port-17/1)#vlan 181
   
   [local](config-port-17/1-vlan-181)#no shutdown
   
   [local](config-port-17/1-vlan-181)#bind interface sgs mme
   
   [local](config-port-17/1-vlan-181)#end

Post-Activation Procedure

1. Save the current configuration to the Flash drive for backup.
2. Use the Naming conventions as per Operator Nomenclature:

   [local] #save configuration /flash/Config_Date_After_activity.cfg -r -no

3. Enter the show support details command in order to display the details of the chassis:

   [local] #show support details

4. Enter these commands in order to capture the activity statistics:

   local]#show sgs-service all
   
   [local]#show sgs-service vlr-status full
   
   [local]#show sgs-service statistics all
   
   [local]#show crash list
   
   [local]#show alarm all
   
   [local]#show snmp trap history
   
   [local]#show configuration errors

5. Enter these commands in order to capture the hardware statistics:

   [local]#show task resource
   
   [local]#show alarm outstanding
   
   [local]#show cpu table
   
   [local]#show port utilization table
   
   [local]#show npu utilization table
   
   [local]#show snmp trap
   
   [local]#show card table all

6. Enter these commands in order to capture the service status:

   [local]#show mme-service all
   
   [local]#show mme-service db record all
   
   [local]#show mme-service enode-association all
   
   [local]#show mme-service id summary
   
   [local]#show mme-service session full
   
   [local]#show session disconnect-reasons
   
   [local]#show session progress
   
   [local]#show mme-service statistics
   
   [local]#show hss-peer-service service all
   
   [local]#show subscriber mme-only summary
   
   [local]#show subscriber mme-only data-rate
   
   [local]#show hss-peer-service statistics all
   
   [local]#show egtp-service all
   
   [local]#show egtpc statistics
   
   [local]#show diameter peers full
   
   [local]#show sgs-service all
   
   [local]#show sgs-service vlr-status full

   Note: This output is captured with reference to Long Term Evolution (LTE) network. If the chassis includes other services, then include related statistics.

Rollback Process

In the event that the new configuration or changes do not work properly or other problems arise, revert to the previous configuration:

1. Enter these commands in order to remove the SG interface and SG service from the configured context:

   [local]#config
   
   [local](config)#context mme
   
   [mme](config-ctx)#no interface sgs
   
   [mme](config-if-eth)#exit
   
   [mme](config-ctx)#no sgs-service sgs_svc

2. Enter these commands in order to remove the SG service association from MME service:

   [mme](config-ctx)#mme-service mme_svc
   
   [mme](config-mme-service)#no associate sgs-service
   
   [mme](config-mme -service)#end
   
   

3. Enter these commands in order to remove the VLAN configured for the SG interface:

   [local]#config
   
   [local](config)#port ethernet 17/1
   
   [local](config-port-17/1)#no vlan 181
   
   [local](config-port-17/1)#end

Statistics/Status

show sgs-service service-name <name>
    show sgs-service statistics
    show sgs-service vlr-status { full }
    show mme-service session full

Verify

There is currently no verification procedure available for this configuration.

Troubleshoot

There is currently no specific troubleshooting information available for this configuration.