Control of token holding in multi-token optical network

A method of operating a multi-token optical communications network the network having optical channels between the node and other nodes, the network being arranged so that nodes hold and pass unique tokens, each token indicating to a node that a corresponding one or more of the optical channels is available for transmission while that node holds that token, during a token holding time, the method comprising:

• queuing packets in a buffer before transmission,
• controlling the buffer to forward at least one initial packet from the buffer to a transmitter for transmitting packets to the other nodes over the optical channels, once a token has been received, for transmission over an optical channel corresponding to the token and according to the token hold time,
• after the at least one initial packet is forwarded from the buffer to the transmitter, determining how much of the token holding time remains, and
• after determining how much of the token holding time remains, controlling the buffer to forward a further packet from the buffer to the transmitter according to the remaining token holding time.

An optical network having a first node and other nodes, each of the nodes being suitable for a multi-token optical communications network, the network having optical channels between the nodes, the network being arranged so that nodes hold and pass unique tokens, each token indicating to a node that a corresponding one or more of the optical channels is available for transmission while that node holds that token, during a token holding time, the first node comprising:

• a transmitter for transmitting packets to the other nodes over the optical channels,
• a buffer for queuing packets before transmission by the transmitter, and
• a transmit controller configured to:
• control the buffer to forward at least one initial packet from the buffer to the transmitter once a token has been received, the at least one initial packet forwarded to the transmitter for transmission over an optical channel corresponding to the token and according to the token hold time, and the first node being arranged to have a different token holding time than the other nodes on at least some of the optical channels;
• after the at least one initial packet is forwarded from the buffer to the transmitter, determine how much of the token holding time remains;
• and
• after determining how much of the token holding time remains, control the buffer to forward a further packet from the buffer to the transmitter according to the remaining token holding time.

A method of operating a multi-token optical communications network the network having optical channels between a first node and other nodes, the network being arranged so that nodes hold and pass unique tokens, each token indicating to a node that a corresponding one or more of the optical channels is available for transmission while that node holds that token, during a token holding time, the method performed at the first node and comprising:

• queueing packets in a buffer before transmission;
• controlling the buffer to forward at least one initial packet from the buffer to a transmitter for transmitting packets to the other nodes over the optical channels, once a token has been received, for transmission over an optical channel corresponding to the token and according to the token hold time, wherein the first node has a different token holding time than the other nodes for at least some of the optical channels channels;
• after the at least one initial packet is forwarded from the buffer to the transmitter, determine how much of the token holding time remains;
• and
• after determining how much of the token holding time remains, control the buffer to forward a further packet from the buffer to the transmitter according to the remaining token holding time.