Methods are disclosed for determining a link Op from among a plurality of host devices on a LAN, for exchanging control messages between a communication server and one or more sites having a link Op and a listening Op and for the link Op and/or listening Op to detect and recover from missing packets in a sequence of IP packets received from the server. The link Op and listening Op join a control multicast group address to receive control messages from the server. The link Op establishes a reliable message transfer session with the server. Upon the link Op detecting a missing packet, the link Op may request that the communication server resend the packet. Upon the listening Op detecting a missing packet, the listening Op determines whether the link Op will request retransmission of the missing packet. If the link Op is determined to not request retransmission of the missing packet, the listening Op requests retransmission of the missing packet or accepts the packet as missing and processes an out-of-sequence packet. If the link Op is determined to request retransmission of the missing packet, the listening Op discards the packet and relies upon the link Op to request retransmission of the missing packet.