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IMG 1010 - Managing Poor Network Connections

Overview:

Feature F-1667 'Ability for GCEMS to handle Satellite Connections to the IMG' allows the IMG to handle unstable connections between the IMG and GCEMS (Host). Communications between GCEMS and the IMG are made using TCP/IP. TCP/IP connections can face drawbacks such as high round trip delays and link errors. High delays and link errors can cause errors when the GCEMS and the IMG pass information between each other. An example of GCEMS to Host communication would be during the configuration process. F-1667 will offer customers with poor network connectivity a smoother Host(GCEMS) to IMG interaction by stopping any unnecessary re-configurations from happening on the IMG. Feature F-1667 continually checks for the link behavior as described below:

Link Up Detection:

Feature F-1667 will begin a timer mechanism upon detecting a 'Link-Up' state between the IMG and GCEMS. The timer value is set by the user. If GCEMS sees that a Link-Up is detected, it will wait the specified amount of time before declaring the link is up. If during this timer period a 'Link Down' state is detected between the IMG and GCEMS, the 'Link Up' state is never passed to the different processes running within GCEMS. If however the timer expires the 'Link Up' state is then passed to the different processes running within GCEMS. The timer described above is used to guard against a burst of connects and disconnects within a short interval of time. See diagram below which displays the Link Up/Link Down Detection scheme.

  • Initially the link state between the GCEMS and IMG goes from the Link Down state to the Link Up State. When the Link Up state is identified, a LINK_UP_REPORT_TIMER is started. No information is sent while the timer is counting.

  • The link state changes from Link Up to Link Down before the LINK_UP_REPORT_TIMER expires. This stops the LINK_UP_REPORT_TIMER. No information has been passed between the GCEMS and IMG because LINK_UP_REPORT_TIMER did not expire indicating the network had gone to Link Down state again

  • The link state then changes from Link Down to Link Up. When the Link Up state is identified, a LINK_UP_REPORT_TIMER is started. No information is sent while the timer is counting.

  • The LINK_UP_REPORT_TIMER expires. Information can now be passed between the GCEMS and IMG
     

Example:

  • GCEMS starts sending a configuration file to the IMG. The link state is initially in the Link Up state.

  • The link then changes its state to the Link Down state.

  • Over the next fifty seconds the network bounces between Link Up state and Link Down state. No information is passed between GCEMS and IMG.

  • Eventually the network stabilizes. The link state now goes to Link Up state. The LINK_UP_REPORT_TIMER starts and after 50 seconds expires. Since the timer has expired, this indicates that network has now been up for at least 50 seconds. The network is now in a stabile state.

  • GCEMS will start its re-configuration process. Re-Configuration will depend on the validation of the configuration tags within the IMG.

Configuration:

To configure this feature an environment variable will need to be added to the Defaults File. Go to /opt/dialogic/IMG/GateControlEMS/Defaults and using a text editor add the LINK_UP_REPORT_TIMER environment variable shown below. The LINK_UP_REPORT_TIMER value can range from 0-3600 seconds. The default value if this environment variable is not added will be 0. Once this value is set the GCEMS server will need to be reset for the value to hold.

 

# User Overrides Begin

LINK_UP_REPORT_TIMER:60

# User Overrides End

 

LOG_DIR:/opt/dialogic/common/log

STATS_DIR:/opt/dialogic/common/stats

CONFIG_DIR:/opt/dialogic/common/config

LICENSE_DIR:/opt/dialogic/common/license

BACKUP_DIR:/opt/dialogic/common/backup

LLC_SWITCHBACK_MODE:1

LOG_LEVEL:1

STATS_FREQUENCY:5

FILE_MAX_SIZE:25

APP_DISABLED_TIMEOUT:1200

PRODUCT:IMG

 

Additional Information:

Support:

  • This feature does not support using poor quality networks between any Host Processes such as CommManager, GateManager, DataManager, ClientView or EventView

  • This feature does not support using poor quality networks between GCEMS and its Redundant Pair.

  • This feature does not support using poor quality networks between GCEMS and either a Primary or Secondary redundant SS7 server.

  • This feature does support using poor quality networks between GCEMS and a remote SS7 node.
     

Miscellaneous:

  • When configuring the IMG, the screen that appears displays the timeout value that is configured in the Defaults file. See below!SC_F-1667_Configuration_status_screen.png|title=!

  • Link Up state is defined as when GCEMS receives a poll message from the IMG and successfully processes the nodes information including the Logical Node ID, Physical Node ID, and IP address. Another poll message must be received within 6 seconds to maintain Link Up status.

  • After second poll message is processed, to maintain a link up state, a message (poll or other message) must be received within 15 seconds or the link is considered down.

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