Those looking for a fast and reliable modem that is compatible with both Mac and Windows operating systems can look at the Motorola SURFboard SB6121 (575319-019-00) 199.68 Mbps cable modem. This model uses the SNMP and HTTP remove management protocol along with the TCP/IP network transport protocol. This unit features a 195 Mbps transfer rate and it contains four different multiplexed channels. It features a variety of line coding formats and it is compatible with 32 QAM, 16 QAM, and QPSK line coding. Other features of the modem include IPv6 support, auto-negotiation, IPv4 support, and auto-uplink for users to take advantage of.