Does a gatekeeper participate in MSD? (Q85)

The information in this article applies to:

H.323 is contradictory on this. It says that only endpoints take part in the master-slave determination, or MSD, and that a gatekeeper is not an endpoint (our emphasis):

• Section 6.2.8.4/H.323: "The H.245 Master-slave determination procedures are used to resolve conflicts between two endpoints..."
• Section 3.14/H.323: "endpoint: An H.323 terminal, Gateway, or MCU. An endpoint can call and be called. It generates and/or terminates information streams."
• Section 3.15/H.323: "gatekeeper: The Gatekeeper (GK) is an H.323 entity on the network that provides address translation and controls access to the network for H.323 terminals, Gateways and MCUs. The Gatekeeper may also provide other services to the terminals, Gateways and MCUs such as bandwidth management and locating Gateways."

Then it goes on to discuss the gatekeeper's role in MSD, e.g.:

• Section 8.4.3.4/H.323: "During master-slave determination [A4b], if the Gatekeeper's terminalType is greater than the terminalType received in the masterSlaveDetermination message, the Gatekeeper may attempt to become master for the call."
• Section 8.4.3.5/H.323: "The H.245 messages are then exchanged as previously described in procedures C1) to C10) with the Gatekeeper taking part in all master-slave determination procedures as the Active MC (C2)."

As with so many things that a routing gatekeeper must do, it can take part in the MSD as long as it behaves as if it were an endpoint--as long as the "real" endpoints believe that they are talking to another endpoint.