To ensure efficient device failover to the backup/secondary application server, the SBC uses the Address Reachability Service (ARS) to determine if the target 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:
recoveryAlgProbeDuration: 1 secondrecoveryAlgProbeInterval: 1 secondrecoveryAlgProbeMethod: sip-optionsrecoveryAlgProbeNumResponses: 1recoveryAlgTimerDuration: 1 secondrecoveryAlgorithm: 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.
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.
Command Syntax
% set profiles services sipArsProfile <profile name> blkListAlgRetryAfterType sip-503 blkListAlgTimeoutsDuration <1-3600> blkListAlgTimeoutsNumTimeouts <1-3600> blkListAlgTimeoutsType sip-invite blkListAlgorithms <retryafter|timeouts> failureResponseCodes <400-699 | all |all4xx | all5xx | all6xx> midDialogArsScreenLevel <always | never | onlyIfNotBlackListDueto503> recoveryAlgProbeDuration <1-3600> recoveryAlgProbeInterval <1-600> recoveryAlgProbeMethod sip-options recoveryAlgProbeNumResponses <1-32> recoveryAlgTimerDuration <1-3600> recoveryAlgorithm <probe|timer>
Command Parameters
The SIP ARS Profile Parameters are as shown:
SIP ARS Profile Parameters
Parameter | Length/Range | Description |
|---|---|---|
| 1-23 |
|
| N/A | Use to specify the SIP status code type which includes a 'Retry-After' value (currently, the only supported value is
|
| 1-3600 | Duration (in seconds) in which the specified number of timeouts must occur. (default = 1). |
| 1-3600 | The number of timeout events for a single INVITE transaction (including any retransmissions) before black listing the address. (default = 1). |
| N/A | The timeout trigger type (currently, only
|
| N/A | Identifies blacklisting algorithm to use for this ARS Profile. Select one or both.
|
failureResponseCodes | 400-699, or | Use this parameter to define one or more response codes to treat as failure responses. The options include the following:
INFO: When you use more than one value, enclose the values in square brackets [ ], separating each value with a space. Entering a value without using brackets appends the value to the existing configuration. NOTE: Ensure |
midDialogArsScreenLevel | N/A | Use this parameter to control when to apply ARS to a mid-dialog request.
|
| 1-3600 | Duration (in seconds) in which the specified number of responses must occur. (default = 1). |
| 1-600 | The probe interval value, in seconds. (default = 1). |
| N/A | Specifies the probe method (currently, only
|
| 1-32 | The number of consecutive responses to occur before removing an entry from the black list. (default = 1). |
| 1-3600 | Duration (in seconds) that the IP address remains blacklisted. (default = 1). |
| N/A | The recovery algorithm to use once the peer is blacklisted.
|
Command Examples
The following example configures a SIP ARS profile named "ARSPROFILE1" using the various objects and parameters.
% set profiles services sipArsProfile ARSPROFILE1
blkListAlgorithms retryafter,timeouts
blkListAlgTimeoutsType sip-invite
blkListAlgTimeoutsNumTimeouts 45 blkListAlgRetryAfterType
sip-503
% set profiles services sipArsProfile ARSPROFILE1
blkListAlgTimeoutsDuration 34 recoveryAlgProbeDuration
546 recoveryAlgProbeInterval 78 recoveryAlgProbeMethod
sip-options recoveryAlgProbeNumResponses 6
recoveryAlgTimerDuration 456 recoveryAlgorithm probe
% show profiles services sipArsProfile
sipArsProfile ARSPROFILE1 {
blkListAlgorithms timeouts,retryafter;
blkListAlgTimeoutsType sip-invite;
blkListAlgTimeoutsNumTimeouts 45;
blkListAlgTimeoutsDuration 34;
blkListAlgRetryAfterType sip-503;
recoveryAlgorithm probe;
recoveryAlgTimerDuration 456;
recoveryAlgProbeMethod sip-options;
recoveryAlgProbeInterval 78;
recoveryAlgProbeNumResponses 6;
recoveryAlgProbeDuration 546;
}
To configure a single failureResponseCodes value for a SIP ARS Profile:
% set profiles services sipArsProfile ARSPROFILE1 failureResponseCodes 404
To set multiple failureResponseCodes values:
% set profiles services sipArsProfile ARSPROFILE1 failureResponseCodes [404 503 all6xx]
To delete a single failureResponseCodes value:
% delete profiles services sipArsProfile ARSPROFILE1 failureResponseCodes all6xx
To delete all failureResponseCodes values:
% delete profiles services sipArsProfile ARSPROFILE1 failureResponseCodes []
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