To ensure achieve efficient device failover to the a backup/secondary application server, the
uses the Address Reachability Service (ARS) Application Server, the SBC uses ARS to determine if the target a server is reachable, providing the ability to temporarily "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 when specified criteria are met. The ARS profile defines when to blacklist a peer and the recovery algorithm that defines when to remove blacklisting, restoring the peer into service. An ARS profile can be assigned to the services section of a SIP trunk group to enforce trigger 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
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 commandRefer to Address Reachability Service for more information on using ARS and ARS profiles.
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| Path_Check_Profile_vs_ARS_Profile |
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| Path_Check_Profile_vs_ARS_Profile |
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% set profiles services sipArsProfile <profile name>
blkListAlgRetryAfterType sip-503
blkListAlgTimeoutsDuration <1-3600>
blkListAlgTimeoutsNumTimeouts <1-3600>
blkListAlgTimeoutsType sip-invite
blkListAlgorithms <retryafter|timeouts> | timeouts | noRetryAfer>
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>
blkListAlgNoRetryAfterNum503 <1-3600>
blkListAlgNoRetryAfterDuration <1-3600> |
Command Parameters
The SIP ARS Profile Parameters are as shown:
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| 0 | Table |
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| 1 | SIP ARS Profile Parameters |
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Parameter | Length/Range | Description |
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sipArsProfile
| 1-23 | <profile name> – The name of the SIP Address Reachability Service profile.
| blkListAlgorithms
| N/A | Identifies blacklisting algorithm to use for the ARS Profile. Any combination of triggers can be specified for a profile. noRetryAfer - trigger blacklisting when a peer endpoint sends SIP 503 responses without a Retry After header at a rate that exceeds a number defined by blkListAlgNoRetryAfterNum503 within the time interval defined by blkListAlgNoRetryAfterDuration.
retryafter – Use the blkListAlgRetryAfterType (trigger) as the blacklisting criteria.timeouts (default) – Use the timeout of the specified SIP message for blacklisting the server. The objects blkListAlgTimeoutsType, blkListAlgTimeoutsNumTimeouts, and blkListAlgTimeoutsDuration must also be specified.
| blkListAlgNoRetryAfterNum503
| 1 - 3600 | The number of SIP 503 responses without a Retry After header events sent by a peer to trigger blacklisting of that peer endpoint. The default is 1. | blkListAlgNoRetryAfterDuration
| 1 - 3600 | The duration, in seconds, in which the SIP 503 responses without a Retry After header events must occur to trigger blacklisting of the peer sending the responses. The default is 1. | blkListAlgRetryAfterType
| N/A | Use to specify the SIP status code type which includes a 'Retry-After' value (currently, the only supported value is sip-503). sip-503 – When a SIP 503 message is received with Retry-After field from downstream server, this option puts that server into blacklist to prevent new call requests (SIP INVITEs) from retransmitting, and starts a Recovery Algorithm to recover the server from blacklist after the duration specified in the Retry-After header contained in the received SIP 503 message.
| blkListAlgTimeoutsDuration
| 1-3600 | Duration (in seconds) in which the specified number of timeouts must occur. (default = 1). | blkListAlgTimeoutsNumTimeouts
| 1-3600 | The number of timeout events for a single INVITE transaction (including any retransmissions) before black listing the address. (default = 1). | blkListAlgTimeoutsType
| N/A | The timeout trigger type (currently, only sip-invite is available): sip-invite – Use SIP INVITE messages as a timeout trigger.
blkListAlgorithms | N/A | Identifies blacklisting algorithm to use for this ARS Profile. Select one or both. retryafter – Use the blkListAlgRetryAfterType (trigger) as the blacklisting criteria.timeouts (default) – Use the timeout of the specified SIP message for blacklisting the server. The objects blkListAlgTimeoutsType, blkListAlgTimeoutsNumTimeouts, and blkListAlgTimeoutsDuration must also be specified.
| failureResponseCodes | 400-699, or
(all, all4xx, all5xx, all6xx) | Use this parameter to define one or more response codes to treat as failure responses. The options include the following: 400-699 – Enter a single code, or enter multiple codes within square brackets and separating each entry with a space. For example, [409 505 699]all – include all response codes from 400-699all4xx – include all 4xx response codesall5xx – include all 5xx response codesall6xx – include all 6xx response codes
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 failureResponseCodes values for Path Check Profile and SIP ARS Profile within the same zone/trunk group use similar values to avoid unexpected behavior. For example, it is not advisable to set Path Check Profile failureResponseCode to "all" and SIP ARS Profile failureResponseCodes to "all4xx" and "all6xx". See Path Check Profile (CLI). | midDialogArsScreenLevel | N/A | Use this parameter to control when to apply ARS to a mid-dialog request. always – ARS is applied to all mid-dialog requests in a call.never (default) – ARS is not applied to mid-dialog requests.onlyIfNotBlackListDueto503 – ARS is applied to mid-dialog requests unless blacklist due to 503 is encountered.
| recoveryAlgProbeDuration
| 1-3600 | Duration (in seconds) in which the specified number of responses must occur. (default = 1). | recoveryAlgProbeInterval
| 1-600 | The probe interval value, in seconds. (default = 1). | recoveryAlgProbeMethod
| N/A | Specifies the probe method (currently, only sip-options is available). | recoveryAlgProbeNumResponses
| 1-32 | The number of consecutive responses to occur before removing an entry from the black list. (default = 1). | recoveryAlgTimerDuration
| 1-3600 | Duration (in seconds) that the IP address remains blacklisted. (default = 1). | recoveryAlgorithm
| N/A | The recovery algorithm to use once the peer is blacklisted. probe (default) – The ARS initiates an active "ping" to the blacklisted server until it gets a response. Once the number of consecutive responses are received as defined by the recoveryAlgProbeNumResponses parameter, the address is removed from the blacklist.timer – The ARS removes the entry for the blacklist after a configured duration.
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% delete profiles services sipArsProfile ARSPROFILE1 failureResponseCodes all6xx |
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To delete all failureResponseCodes values:
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