Physical layer collision avoidance (PLCA) uses a different approach. Each node is assigned a unique node ID that has no relationship to the MAC address. ID #0 is the PLCA coordinator and the other nodes are “followers”. The coordinator must know the total number of nodes, including itself. ID #0 issues a beacon which is a unique 20-bit symbol, triggering a PLCA cycle. Then, all the nodes reset their transmit opportunity timers which are by default internal 32-bit timers. Based on their ID number, in a round-robin fashion, each node takes their turn or opportunity to commit to transmit on the bus, beginning with node 0. If a node has nothing to transmit during its turn, that node is silent. Recognizing silence, all the transmit opportunity timers quickly timeout, triggering the next ID number’s turn to commit to transmit. If a node has pending data ready to transmit onto the bus during its turn, that node issues a commit (a unique 20-bit symbol), and all other nodes wait until the committed node transmits one Ethernet frame. The shortest Ethernet frame is 64 Bytes and the longest Ethernet frame is 1,518 Bytes. The IEEE802.cg specification identifies a default transmit opportunity timer of 32 bits. The NCN26010 default transmit opportunity timer is 24 bits, but it can be programmed with an internal register across the SPI bus to other values including 32 bits. This feature provides some flexibility to the network. A shorter cable length network may benefit from a shorter timeout, while a longer cable length network might benefit from a longer timeout.