Hi, I think that 2 is correct and the MC is not ignoring the OLC ack. He will need to know when the multicast address is not used. Roni Even Polycom Israel -----Original Message----- From: Choi Seung Geol [mailto:csg@BLUEBIRD.CO.KR] Sent: Monday, July 16, 2001 9:24 AM To: ITU-SG16@MAILBAG.INTEL.COM Subject: (H.323) Distibuting Media Stream address, OLC & OLC Ack? Below is the paragraph excerpted from H.323 ( 8.3.3. Media stream address distribution ). In multicast, the multicast addresses are assigned by the MC and distributed to the endpoints in the communicationModeCommand. It is the responsibility of the MC to allocate and assign unique multicast addresses. The endpoint shall signal an openLogicalChannel to the MC with the assigned multicast address. The MC shall forward the openLogicalChannel to each receiving endpoint. In cases where media from multiple endpoints are transmitted on a single session (e.g. single multicast address), the MC shall open a logical channel to each endpoint receiving media from an endpoint in the conference. ---------------- "Forwarding of OLC" is a little ambiguous. 1. use the same LCN ? 2. what about OLC ack? for example, when there is a conference composed of a MCU and Terminal A, B, and C, only Terminal A speaks and B, C listens to A. then, MCU will broadcast communicationModeCommand that contains only one entry without specifying destination and specifying the multicast address of Terminal A. then, Terminal A will send OLC to MCU. From this point on, I am not sure. Possible interpretations are.. 1. MC will forward the OLC to Terminal B and C. And The Terminal B and C will send OLC Ack To MC. At the time of receving OLC Ack, what should MC do? forward the 2 OLC Ack pdus to Terminal A ? It seems not proper.. 2. MC will send the OLC Ack to Terminal A and send the OLC to Terminal B and C. and then OLC Ack from the Terminal B and C will be ignored ? 3. MC will forward the OLC to Terminal B and C, and sends OLC Ack to Terminal A only if both Termanl B and C reply to the OLC. what if the new Terminal D joins the conference ? which is correct?