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    Configuring MGCP ALG (NSM Procedure)

    MGCP is a text-based Application Layer Protocol used for call setup and call control between the media gateway and the media gateway controller (MGC).

    To configure MGCP ALG:

    1. In the NSM navigation tree, select Device Manager > Devices.
    2. Click the Device Tree tab, and then double-click the device for which you want to configure MGCP ALG.
    3. Click the Configuration tab. In the configuration tree, select Security > Alg > Mgcp.
    4. Add or modify settings as specified in Table 1.
    5. Click one:
      • OK—Saves the changes.
      • Cancel—Cancels the modifications.

    Table 1: MGCP ALG Configuration Details

    Option

    Function

    Your Action

    Inactive Media Timeout

    Specifies the maximum length of time (in seconds) a call can remain active without any media (RTP or RTCP) traffic within a group. Each time an RTP or RTCP packet occurs within a call, this timeout resets. When the period of inactivity exceeds this setting, the temporary openings (pinholes) in the firewall MGCP ALG opened for media are closed. Note that upon timeout, while resources for media (sessions and pinholes) are removed, the call is not terminated.

    Select a value between 10 and 2,550 seconds. The default is 120 seconds.

    Transaction Timeout

    Specifies a timeout value for MGCP transactions. A transaction is a signaling message, for example, a NTFY from the gateway to the call agent or a 200 OK from the call agent to the gateway. The Juniper Networks device tracks these transactions, and clears them when they time out.

    Enter a value from 3 to 50 seconds.

    Maximum Call Duration

    Sets the absolute maximum length of a call. When a call exceeds this parameter setting, the MGCP ALG tears down the call and releases the media sessions.

    Select a value between 3 and 7,200 minutes. The default is 720 minutes.

    Connection Flood Threshold

    Limits the number of new connection requests allowed per media gateway per second.

    Enter a value from 2 to 10,000.

    Message Flood Threshold

    Limits the rate per second at which message requests to the media gateway are processed. Messages exceeding the threshold are dropped by the MGCP ALG.

    Enter a value from 2 to 50,000 seconds per media gateway. By default, this feature is disabled.

    Permit NAT Applied

    Specifies how unidentified MGCP messages are handled by the Juniper Networks device. Permitting unknown messages can compromise security and is not recommended. However, in a secure test or production environment, this statement can be useful for resolving interoperability issues with disparate vendor equipment. By permitting unknown MGCP (unsupported) messages, you can get your network operational and later analyze your VoIP traffic to determine why some messages were being dropped.

    This statement applies only to received packets identified as supported VoIP packets. If a packet cannot be identified, it is always dropped. If a packet is identified as a supported protocol, the message is forwarded without processing.

    Select this option to permit unidentified MGCP messages. By default, unknown (unsupported) messages are dropped.

    Permit Routed

    Specifies that unknown messages be allowed to pass if the session is in Route mode. (Sessions in Transparent mode are treated as Route mode.)

    Select this option.

    Published: 2013-01-06