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To achieve efficient device failover to the backup/secondary Application Server, the SBC uses the Address Reachability Service (ARS) to determine if a server is reachable, providing the ability to "blacklist" a server IP address if it is found to be unreachable, as well as the ability to remove the server from the blacklisted state. ARS profiles can be created to configure blacklisting and recovery algorithm variants.
These ARS profiles can be assigned to the services section of a SIP trunk group to enforce the blacklisting and recovery of any SIP peer(s) associated with the trunk group. If no recovery algorithm is specified when configuring a SIP ARS profile, the recovery algorithm default values are used as indicated below:
Recovery Alg Probe Duration: 1 second
Recovery Alg Probe Interval: 1 second
Recovery Alg Probe Method: sip-options
Recovery Alg Probe Num Responses: 1
Recovery Alg Timer Duration: 1 second
Recovery Algorithm: probe
Traffic is shared across all SBC Session Control Module (SCM) processes. For INVITE time outs, an IP Peer is blacklisted only when the same SCM process reaches the configured number of INVITE timeouts within the configured timeout duration.
For a single shot call scenario (i.e. lab testing), it may be necessary to gather additional timeouts to see an IP Peer get blacklisted. Once the peer is blacklisted, the same data is available across all SCM processes.
Similarly, when a peer is not blacklisted but is in the process of being blacklisted because of time outs, the 'show' command to check ARS Status may give inconsistent results depending upon the SCM process which responds first to the command.
On SBC main screen, go to Configuration > Profile Management > Category: Service Profiles > Sip Ars Profile.
The Sip Ars Profile window is displayed.
To edit any of the Sip Ars Profile in the list, click the radio button next to the specific Sip Ars Profile name.
The Edit Selected Sip Ars Profile window is displayed below.
Make the required changes and click Save at the right hand bottom of the panel to save the changes made.
To create a new Sip Ars Profile, click New Sip Ars Profile tab on the Sip Ars Profile List panel.
The Create New Sip Ars Profile window is displayed.
The following fields are displayed:
Specifies the name of the SIP ARS Profile.
Use this parameter to define one or more response codes to treat as failure responses. Include one or more of the following values, separating each entry with a comma: - 400-699 - list codes individually
- all – include all response codes from 400-699
- all4xx – include all 4xx response codes
- all5xx – include all 5xx response codes
- all6xx – include all 6xx response.
In EMA, the Failure Response Codes are configured as comma separated values. In CLI, the values of the Failure Response Code are separated by space.
Specifies the type of BLACKLISTING ALGORITHM for this ARS profile:
Specifies the TYPE of timeout trigger for the blacklisting TIMEOUTS algorithm:
Specifies the number of timeout events that must occur before black listing the address. Must be 1-3600; default value is 1.
Specifies the DURATION (in seconds) in which the specified number of timeouts should occur. Must be 1-3600. SIP-INVITE timeout is the only event that is supported as of now.
Specifies the SIP status code which has a Retry After value:
Use this parameter to control when to apply ARS to a mid-dialog request.
Specifies the type of recovery algorithm used after an IP address has been blacklisted:
Specifies the DURATION (in seconds), for which the IP address will remain blacklisted. Must be 1-3600.
Specifies the probe (ping) METHOD for blacklist recovery:
Specifies the probe INTERVAL (in seconds) for blacklist recovery. Must be 1 - 600 (default is 1).
Specifies the number of consecutive responses that must occur before removing an entry from the black list. Must be 1 - 32 (default is 1).
Specifies the DURATION (in seconds) in which the specified number of probe responses should occur. Must be 1-3600 (default is 1).
Note Sonus recommends to not configure Path Check Profile and SIP ARS Profile on the same peer to avoid unexpected results. As a general rule, the Path Check Profile is configured on the access leg where there is less traffic, and the ARS Profile is configured on the peer leg where there is continuous traffic.
Sonus recommends to not configure Path Check Profile and SIP ARS Profile on the same peer to avoid unexpected results. As a general rule, the Path Check Profile is configured on the access leg where there is less traffic, and the ARS Profile is configured on the peer leg where there is continuous traffic.
To copy any of the created Sip Ars Profile and to make any minor changes, click the radio button next to the specific Sip Ars Profile to highlight the row.
Click Copy Sip Ars Profile tab on the Sip Ars Profile List panel.
The Copy Selected Sip Ars Profile window is displayed along with the field details which can be edited.
Make the required changes to the required fields and click Save to save the changes. The copied Sip Ars Profile is displayed at the bottom of the original Sip Ars Profile in the Sip Ars Profile List panel.
To delete any of the created Sip Ars Profile, click the radio button next to the specific Sip Ars Profile which you want to delete.
Click Delete at the end of the highlighted row. A delete confirmation message appears seeking your decision.
Click Yes to remove the specific Sip Ars Profile from the list.