Token Ring phát sóng địa chỉ (0xC0-00-FF-FF-FF-FF). Một khung bằng cách sử dụng Ring địa chỉ phát sóng Mã được thiết kế để duy trì trên một vòng duy nhất và không được chuyển tiếp bằng đường cầu nguồn Token Ring. Một địa chỉ multicast. Token Ring chức năng địa chỉ. Một địa chỉ chức năng là một loại địa chỉ multicast đó là cụ thể | 18 Part I The Network Interface Layer The Token Ring broadcast address 0xC0-00-FF-FF-FF-FF . A frame using the Token Ring broadcast address is designed to remain on a single ring and is not forwarded by Token Ring source-route bridges. A multicast address. A Token Ring functional address. A functional address is a type of multicast address that is specific to Token Ring and is typically used by Token Ring MAC management frames. Source Address The Source Address field is 6 bytes long and indicates the sending node s unicast address. Payload The Payload field for a Token Ring frame consists of a PDU of an upper layer protocol. Unlike Ethernet there is no minimum frame size and the maximum transmission unit MTU for Token Ring is not a defined number but dependent on factors such as the bit rate and the token holding time. Token Ring MTUs are further complicated by the presence of Token Ring source-routing bridges. More information on Token Ring MTUs for IP datagrams can be found in the section titled IEEE SNAP later in this chapter. Frame Check Sequence The FCS field is a 4-byte CRC that uses the same algorithm as Ethernet to provide a bit-level integrity check of all fields in the Token Ring frame from the Frame Control field to the Payload field. The FCS does not provide bit-level integrity for the Access Control or Frame Status fields. This allows bits in these fields such as the Monitor bit to be set without forcing a recalculation of the FCS. The FCS is checked as it passes each node on the ring. If the FCS fails at any node the Error Detected indicator in the End Delimiter field is set to 1 and the receiving node does not copy the frame. End Delimiter The End Delimiter is a 1-byte field that identifies the end of the frame. Like the Start Delimiter the End Delimiter contains J and K nondata symbols to provide an explicit postamble. The End Delimiter field also contains the following An Intermediate Frame indicator 1 bit used to indicate whether this frame
