AudioCodes Mediant 4000 SBC, User Manual

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CHAPTER 25 Routing SBC
Mediant 4000 SBC | User's Manual
General
Destination Type Destination Tag
Routing Tag Name Port
Configuring a Routing Response Timeout
If you have routing rules in the IP-to-IP Routing table that need to query external servers (e.g., an
LDAP server or ENUM server) on whose responses the device uses to determine where to route
the SBC calls, you can configure a timeout for the responses. If the timeout expires before the
device receives a response from the server, the device sends a routing failure message (SIP 500)
to the caller, or uses an alternative routing rule (if configured).
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To configure a timeout for routing query responses:
1. Open the SBC General Settings page ( Setup menu > Signaling & Media tab > SBC folder >
SBC General Settings ).
2. In the 'Routing Timeout' (SbcRoutingTimeout) field, enter the maximum duration (in seconds)
that the device is prepared to wait for a response from external servers.
3. Click Apply .
Configuring SIP Response Codes for Alternative
Routing Reasons
The Alternative Routing Reasons table lets you configure up to 20 SIP response codes for SBC call
release (termination) reasons for triggering alternative routing. This feature works together with the
Proxy Hot Swap feature, which is configured in the Proxy Sets table.
In addition to configuring the response codes described in this section, you need to configure the
following:
■ A Proxy Set with one or more addresses (proxy servers) and whose 'Proxy Hot Swap'
parameter is configured to
Enable (see Configuring Proxy Sets ).
■ An IP-to-IP Routing rule whose 'Destination IP Group' parameter is assigned a Server-type IP
Group that is associated with the above Proxy Set (see
Configuring SBC IP-to-IP Routing
Rules ).
■ An alternative IP-to-IP Routing rule for the above rule.
Alternative routing based on SIP response codes operates as follows:
1. The device sends (outgoing) a SIP dialog-initiating message (e.g., INVITE, OPTIONS, and
SUBSCRIBE) to one of the online proxy servers (addresses) configured for the Proxy Set that
is associated with the destination IP Group of the matched IP-to-IP Routing rule.
2. If there is no response to the sent SIP message, or a "reject" response is received (e.g., SIP
406) that is also configured in the Alternative Routing Reasons table, the device tries to route
the SIP message again (re-transmission) to the same proxy server for a user-defined number of
times, configured by the [HotSwapRtx] parameter. If still unsuccessful, the device tries to
send the message to a different online proxy server of the Proxy Set and if unsuccessful, it
tries another online proxy server, and so on. The order of attempted online proxy servers is
according to the Proxy Set's configuration.
The following can then occur depending on received response codes or no responses:
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