Hi, Everyone:

Just to remind that we have to address the problems of the GK discovery using the GRQ/GCF messages in the H.323 mobile environments.

I like point out that an alternative method was suggested to use the MGA Message.

Both GRQ and MGA messages have problems to discover the GK in mobile environment.

However, the meeting report (TD-56, TD-22c) shows that, as if, MGA mechanism cannot be used in any H.323 mobile communications environment. It is NOT simply true because H.323 mobile communications environments include: Wire-line (copper, cable, fiber), Wireless LAN (multi-megabits to multi-gigabits), and/or Cellular Wireless (picocell, microcell, macrocell) Networking environments.

The problem for the MGA comes up when the bandwidth is very scarce if the MGA message is multicast periodically. For example, in the ellular wireless (macrocell) network, the bandwidth is very scarce. However, this kind of problem is being addressed by sending the "advertise" message in a UNICAST fashion. For example, 3GPP has proposed mobile IP's "agent advertisement message" to be sent in a unicast fashion (instead of multicast) for their cellular wireless (macrocell) networking environment. The price they are paying is to make the mobility solution a quasi-dynamic (instead of truly dynamic).

For all other communications environments [e.g., Wire-line (copper, cable, fiber), Wireless LAN (multi-megabits to multi-gigabits), and/or Cellular Wireless (picocell, microcell)] where the bandwidth is NOT scarce, like mobile IP, the MGA mechanism can be used as appropriate.

However, the use of the MGA message is an OPTION, not mandatory. (This mechanism will help the mobile H.323 to interwork with the mobile IP should anyone to implement mobile IP in the lower network layer.)

So, both GRQ/GCF/GRJ and MGA mechanisms can be used in a complementary manner as appropriate depending on pros and cons of different networking environments.

We will discuss this further. In the meantime, please let me know if you have any questions.

Best regards, Radhika R. Roy AT&T +1 732 420 1580 rrroy@att.com

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