SIP Options Keep Alive - Gateway Busy Out

The 2020 IMG can monitor the status of multiple external SIP gateways by sending periodic SIP OPTIONS messages. If the gateway does not respond to one OPTIONS message the gateway will be considered down or unreachable and attempt to re-route the call to a different gateway. Once the gateway is down or considered unreachable it will take the configured amount of responses to show the gateway as UP or Reachable. SIP Options Keep Alive - Gateway Busy Out follows RFC 3261 SIP: Session Initiation Protocol, Section 11.

 

 

 

Configuration

The procedure below explains how to configure the 2020 IMG to transmit SIP Options messages to a specific gateway to see if it is still alive. Before configuring, the 2020 IMG must have an initial configuration created on it. Follow the Basic Configurations procedure before proceeding. Once all initial steps have been executed the 2020 IMG can be configured for the Gateway Busy Out feature. Follow steps below:

Note: If the Options Keep Alive property is enabled, disable it before changing other Properties in the SIP External Gateway object. Then, re-enable it once the other changes have been made.  This sequence will insure the IMG is configured correctly.

 

Create SIP Signaling Gateway Profile (SGP) and SIP Options Keep Alive

  1. Right Click on the Profiles object and select New SIP SGP. Change the SIP Profile ID to something other than ID:0 to allow the SIP Options Keep Alive object created under the SIP SGP object to be modified.
  2. In the SIP SGP object enter a name in the SIP Profile Name field to identify this object. For more information on the SIP SGP page see SIP SGP.
  3. Right Click on the SIP SGP object just created and select New Options KeepAlive. Modify the fields as needed. Refer to SIP Options Keep Alive - Gateway Busy Out for more information.

SC_SIP_OPTIONS_KeepAlive.png

Number of Responses - Number of responses received before marking the gateway as reachable. Drop down menu has selections from 1 to 10 (Default 3).

Up Timer (s) - Timer to define the interval the IMG will send the OPTIONS message to the gateway when the gateway up and responsive. Timer is in seconds (Default=120 seconds)

Down Timer (s) - Timer to define the interval the IMG will send the OPTIONS message to the gateway when the gateway is down or non responsive. Timer is in seconds (Default=30 seconds)

 

Create SIP signaling stack

  1. Right Click on 2020 IMG Name and select New Signaling. The Signaling Object allows multiple signaling objects to be configured below it. No configuration is needed in this object.

  2. Right Click on Signaling Object just created and select New SIP. Select the SIP Gateway Profile just created from drop down menu in the Remote IMG’s SIP Profile field. See screen capture below.

    SC_SIP_Options_Keep_Alive_Stack_Config.png

    For more Information refer to SIP Signaling

 

Create Remote Gateway

Create an external network element. To associate the SIP profile created with a remote SIP gateway, an external network element must be created. Follow procedure below to communicate with a remote gateway.

  1. Right-click 2020 IMG EMS and select New External Network Elements. Refer to External Network Elements topic for more information.

  2. Right-click External Network Elements and select New External Gateways. Refer to External Gateways for more information.

  3. Right-click External Gateways and select New External Gateway. Select SIP as the Gateway Signaling Protocol.

  4. Enter a Name in the Name field to identify this gateway.

  5. Enter in the Gateway IP Address field an IP address of the gateway that the 2020 IMG will be communicating with.

  6. Select the SIP SGP created above from the drop down menu in the SIP Profile field.

  7. Select Enable from the OPTIONS Keep Alive field. Refer to External Gateway topic for more information.

SC_SIP_Options_Keep_Alive_GWConfig.png

  1. Once the External Network Elements have been created, they can be associated with Channel Groups through the IP Network Elements object. See below

 

Create SIP Channel Groups:

  1. Right Click on 2020 IMG EMS and select New Routing Configuration. See Routing Configuration for more information.

  2. Right Click on Routing Configuration and select New Channel Groups. This is a container object and no configuration is needed. Below the Channel Groups object, the Channel Group object can be created. Refer to Channel Groups topic for more information.

  3. Right Click on Channel Groups object and select New Channel Group. Enter a name to identify this channel group and change the Signaling Type to SIP using the drop down menu. Refer to SIP Channel Group for more information on configuring a SIP channel group.

 

Insert SIP External Network Element into SIP Channel Group:

  1. Right Click on the SIP Channel group created and select New IP Network Element. Within the IP Network Element field, select from drop down menu, the gateway that will receive the SIP Options messages. See screen capture below.

SC_SIPOptions_Keep_Alive_IPNetElemConfig.png

 

 

EventView Alarms

A new SIP gateway Alarm will appear in both EventView and alarm.log. The alarm indicates the status of a particular SIP Gateway. This alarm will contain the status (either unreachable or reachable) and the IP address of the Gateway. The SIP Gateway Alarm is first sent if the Gateway is considered unreachable. Below are samples of the alarm messages

 

SIP Gateway Alarm

Sep 19 2007 11:08:36.838 X0[88.235.44.169]->H : 00 b9 04 0a 00 03 0a 04 07 00 04 07 cc 09 c9 4a
Sep 19 2007 11:08:36 **Major: Node 0: Entity 0xa Alarm: Unrecognized Alarm 0x4

 

00 b9 - Alarm Message
04 - Reserved
0a - Sequence Number
00 - Logical Node ID
03 - Severity (3=Major)
0a - Alarm Type ALARMentGATEWAY
04 - Gateway Unreachable  03=Gateway Reachable
07 - DATA Length
00 - Gateway Status  0=Down   1=Up
04 07 - GATEWAY ID (1031)
cb 07 65 41 - GATEWAY IP Address (203.7.101.65)
 

Alarm Cleared

This alarm is sent when the Gateway is considered reachable again.

Sep 19 2007 11:12:38.048 X0[88.235.44.169]->H : 00 c1 02 77 00 03 0a 03 07 01 04 07 cc 09 c9 4a
Sep 19 2007 11:12:38 Major: Node 0: Entity 0xa Alarm: Unrecognized Alarm Cleared 0x3

 

00 c1 - Alarm Cleared
02 - Reserved
77 - Sequence Number
00 - Logical Node ID
03 - Severity (3=Major)
0a - Alarm Type Alarm Cleared
03 - Gateway Reachable 04=Unreachable
07 - DATA Length
01 - Gateway Status  0=Down   1=Up
04 07 - Gateway ID
cb 07 65 41 - Gateway IP address

 

 

Call Tracing

Call Tracing will capture the sending/reception of the OPTIONS method and indicate that re-routing has taken place because the gateway is down. See example trace below.

Example Call Trace:

21:24:03.305 SIP (W)
                        <--- [10.129.43.154, 5060 <- 10.129.43.23, 5060]
                       OPTIONS sip:10.129.43.154:5060;ttl=0 SIP/2.0
                       Via: SIP/2.0/UDP 10.129.43.23:5060; rport;branch=z9hG4bK-6df4-1156281802-19999-423
                       Call-ID: 5aa9-1e61-7222006212322-chiloe-0@10.129.43.23CSeq: 1 OPTIONS
                       Max-Forwards: 70
                       To: <sip:10.129.43.154;ttl=0>
                       From: <sip:10.129.43.23>;tag=95ffcd055e0f78f7d5d397020e89288db5f2
                       User-Agent: Dialogic-SIP/10.3.2.57 chiloe 0
                       Contact: <sip:10.129.43.23:5060>
                       Accept: application/ sdp
                       Content-Length: 0

Example entry in Call Trace:

13:12:48.804 CALL(GCL) (01:00003:01) WARNING: Channel Group [Lap_PC],GWIP [10.129.51.137] DOWN, trying next one

 

Additional Information