# Troubleshooting the Service

This chapter provides information and instructions for using the system command line interface (CLI) for troubleshooting issues that may arise during service operation.

Test Commands

In the event that an issue was discovered with an installed application or line card, depending on the severity, it may be necessary to take corrective action.

The system provides several redundancy and fail-over mechanisms to address issues with application and line cards in order to minimize system downtime and data loss. These mechanisms are described in the sections that follow.

Using the GTPU Test Echo Command

This command tests the HNB-GW’s ability to exchange GPRS Tunneling Protocol user plane (GTP-U) packets with the specified peer nodes which can be useful in troubleshooting and/or monitoring.
The test is performed by the system sending GTP-U echo request messages to the specified node(s) and waiting for a response.

IMPORTANT:

This command must be executed from within the context in which at least one HNB-GW service is configured.
The command has the following syntax:

    gtpu test echo src-address src_ip_address{ all | sgsn-address ip_address }

Keyword/Variable | Description
--- | ---
src-address src_ip_address | Specifies the IP address of an interface configured on the system. NOTE: The IP address of the system’s interface must be bound to a configured HNB-GW service prior to executing this command.
all | Specifies that GTP-U echo requests will be sent to all Nodes that currently have sessions with the HNB-GW service.

The following figure displays a sample of this command’s output showing a successful GTPU echo-test from an HNB-GW service bound to address 192.168.157.32 to an SGSN with an address of 192.168.157.2.

    GTPU test echo

    --------------

    SGSN: 192.168.157.2
      Tx/Rx:  1/1  RTT(ms): 24   (COMPLETE)

Using the GTPv0 Test Echo Command

This command tests the HNB-GW’s ability to exchange GPRS Tunneling Protocol version 0 (GTPv0) packets with the specified SGSNs which can be useful troubleshooting and/or monitoring.
The test is performed by the system sending GTPv0 echo request messages to the specified SGSN(s) and waiting for a response.

IMPORTANT:

This command must be executed from within the context in which at least one HNB-GW service is configured.
The command has the following syntax:

    gtpv0 test echo src-address src_ip_address { all | sgsn-address ip_address }

Keyword/Variable | Description
--- | ---
src-address src_ip_address | Specifies the IP address of an interface configured on the system. NOTE: The IP address of the system’s interface must be bound to a configured HNB-GW service prior to executing this command.
all | Specifies that GTP-U echo requests will be sent to all Nodes that currently have sessions with the HNB-GW service.
sgsn-address ip_address | Specifies that GTPv0 echo requests will be sent to a specific SGSN. ip_address is the address of the SGSN to receiving the requests.

The following figure displays a sample of this command’s output showing a successful GTPv0 echo-test from an HNB-GW service bound to address 192.168.157.32 to an SGSN with an address of 192.168.157.2.

    GTPv0 test echo

    --------------

    SGSN: 192.168.157.2
    Tx/Rx: 1/1 RTT(ms):14 (COMPLETE)Recovery: 210(0xD2)

Using the IPsec Tunnel Test Command

This command tests the system’s ability to communicate through an IPsec Tunnel. This functionality is useful for troubleshooting and/or monitoring.
The command has the following syntax:

    test ipsec tunnel ip-pool ip_pool_name destination-ip des_ip_address source-ip src_ip_address

Keyword/Variable | Description
--- | ---
ip_pool_name | The name of the IP pool configured for IPsec Tunnel. ip_pool_name can be from 1 to 63 alpha and/or numeric characters in length and is case sensitive.
des_ip_address | The IP address of destination node of IPsec tunnel.
src_ip_address | The IP address of source node of IPsec tunnel.

Performance Improvement Commands

In the event that an issue of IPC message latency towards core network was discovered with HNB-GW service, it may be necessary to take corrective/preventive action.

The system provides a latency reduction mechanisms in SGSN Global Service Configuration Mode to address latency issues in order to minimize the latency towards core network. These mechanism is described in the section that follow.

Turning off IPC Message Aggregation To Reduce Latency Towards Core Network

This command enables/disables aggregation of IPC messages in the link manager (linkmgr) and session manager (sessmgr).

This command includes options to configure the frequency of aggregated message flushing and the number of packets to be buffered before the flush.
At the HNB-GW node, this command provides a solution to reduce latency while sending the IPC messages toward CN.

IMPORTANT:

This command must be executed from SGSN Global Service Configuration Mode within the context in which the HNB-GW service is configured. Refer Command Line Interface Reference for more information on this command.
The command has the following syntax:

    aggregate-ipc-msg {linkmgr | sessmgr } {flush-frequency frequency | num-msgs number_msgs }

    default aggregate-ipc-msg {linkmgr | sessmgr }

Keyword/Variable | Description
--- | ---
default | Resets the managers to default values for flushing; i.e. 1.
linkmgr | Selects the linkmgr to configure the number of IPC messages to be aggregated and frequency of flushing.
sessmgr | Selects the sessmgr to configure the number of IPC messages to be aggregated and frequency of flushing.
flush-frequency frequency | Configure the frequency, in 100-millisecond intervals, that the aggregated IPC messages will be flushed. frequency : Enter an integer from 1 to 3. Default is 1.
num-msgs number_msgs | Configure the number of IPC messages to aggregate before flushing. number_msgs : Enter the integer 1 (to disable aggregation) or an integer from 2 to 164 to define the number of messages. Default is 10.