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    GTP Path Management Overview

    A GPRS tunneling protocol (GTP) path is active only when both the Packet Data Network Gateway (P-GW) and Serving Gateway (S-GW) are active. The MobileNext Broadband Gateway performs the following functions to check that a peer is active:

    • If path management is enabled, the broadband gateway sends periodic echo requests to all peers identified in the peer information table.
    • When an echo-request message is received from a peer, the broadband gateway sends an echo-response message.
    • If a peer does not respond after a specified number of echo requests, the peer is declared down and all subscriber sessions with the peer are brought down

    This topic covers:

    Default Path Management Configuration

    When you configure a broadband gateway as a P-GW without explicitly configuring path management, the following options are automatically enabled with their default values:

    • echo-n3-requests—Specifies the maximum number of times that the gateway attempts to send a echo-request message. The default is 8 times.
    • echo-t3-response—Specifies the number of seconds that the gateway waits for a response from a peer gateway before sending the next echo-request message. The default is 15 seconds.
    • echo-interval—Specifies the number of seconds that the gateway waits before resending a signaling-request message after a response to an echo request is received. The default is 60 seconds.

      While an echo response from the peer is pending, the broadband gateway does not send new echo requests even if the path management echo-interval elapses. This would occur if echo-t3/echo-n3 is greater than the echo interval and the peer does not respond to the echo request.

      Note: The echo-interval timer functions independently from the echo-n3-requests/echo-t3-response timer.

    • path-management—Specifies whether path management is enabled or disabled on the broadband gateway. By default, control path management is enabled and data path management is disabled.

      Note: If path-management is disabled, the broadband gateway does continue to send echo-response messages to peer-initiated echo-request messages.

    GTP Version Support for Echo Requests and Echo Responses

    Echo messages are sent to the peer using the GTP version that the peer supports. A broadband gateway configured as a GGSN, P-GW, or GGSN/P-GW supports sending echo replies to GTPv0, GTPv1, and GTPv2 echo requests from a peer SGSN or S-GW.

    Published: 2011-11-17