Panasonic DX-600 Service Manual

Also see for DX-600: Network fax guide Technical guide

Contents

238DX-600/800APR 2002Edition 1.07.2. Layer Functions and Technology7.2.1. MAC (Media Access Control)The MAC address is burnt into each network card for establishing addresses for nodes on the network.These addresses are hexadecimal in nature and are unique for each card. The First three bytes from theleft end identify the manufacturer’s code that must be approved by IEEE (Institute of Electrical andElectronics Engineers). The Remaining three bytes on the right half should be kept in a unique manner. ForEthernet connections, multiple stations share the topology, therefore, the identification packet from eachstation should be unique.7.2.2. Network ControlCSMA/CD (Carrier Sense Multiple Access with Collision Detection) If a node is trying to make a link to thenetwork, transmission from another station is prohibited and halted until the data transfer is completed andthe link is off. CSMA/CD and Token Passing are typical techniques used to control the connection. TheGeneral sequence is as follows:Wait for the next available timing to send,Send out a frame,Perform collision sensing simultaneously,Retry to send the same frame up to 16 times if necessary.(Sequence goes by a binary exponential back-off algorithm to avoid periodical incident)802.3 (Ethernet) Frame FormatDestination MAC address: 6 byte (uni-cast or broadcast)If all "1" on 6 byte (FF-FF-FF-FF-FF-FF) means broadcast frame, it is detected by an applicable node, itmust be passed to the upper layer.Also, if the destination MAC address is not matched with that node, the frame is discarded at that nodeimmediately.Token PassingToken passing utilizes a frame called a token, which circulates around the network. A computer that needsto transmit must wait until it receives the token, at which time the computer is permitted to transmit. Whenthe computer is done transmitting, it passes the token frame to the next station on the network.The first station that is powered up on a token-ring network automatically becomes the active monitorstation. Its responsibility is to announce itself to the next active downstream station as the active monitorstation and request that station to announce itself to its next active downstream station. After each stationannounces itself to its next active downstream neighbor, the announcing station becomes the nearest activeupstream neighbor (NAUN) to the downstream station. After each station becomes aware of its NAUN, thebeaconing process continues every seven seconds.XX-XX-XX-XX-XX-XXUnique valueManufacturer IDMGCS:080023Most significant bitPre-amble8 byte Destination MAC address6 byte Source MAC address6 byte Data type2 byte Data46 1500 byte FCS4 byteLeast significant bit