Guaranteeing synchronous message deadlines with the timed token medium access control protocol

Abstract

We study the problem of guaranteeing synchronous message deadlines in token ring networks where the timed token medium access control protocol is employed. Synchronous bandwidth, defined as the maximum time for which a node can transmit its synchronous messages every time it receives the token, is a key parameter in the control of synchronous message transmission. To ensure the transmission of synchronous messages before their deadlines, synchronous capacities must be properly allocated to individual nodes. We address the issue of appropriate allocation of the synchronous capacities. Several synchronous bandwidth allocation schemes are analyzed in terms of their ability to satisfy deadline constraints of synchronous messages. We show that an inappropriate allocation of the synchronous capacities could cause message deadlines to be missed, even if the synchronous traffic is extremely low. We propose a scheme, called the normalized proportional allocation scheme, which can guarantee the synchronous message deadlines for synchronous traffic of up to 33% of available utilization.

Periodic Communication Support in Multiple Access Networks Exploiting Token with Timer

“…If there are m message streams in node i, we divide this node into m sub-nodes, where the token passing time between sub-nodes equals zero. By performing this transformation, a network with multiple message streams in a node can be treated equivalently as one with one message stream per node [6]. We assign the highest priority to aperiodic messages.…”

Token Passing Techniques for Hard Real-Time Communication

“…If the j-th message in the stream S i is put in the transmission queue at time t i,j , then the (j+1)-th will arrive in the transmission queue at time t i,j+1 = t i,j + T i . Without loss of generality, only a stream per node it is considered, since the case of a network with more streams per node can be represented with a logical equivalent one with a stream per logical node, as showed in (Agrawal et al, 1994). We consider that each node i is assigned a bandwidth H i , also called time budget, used to bound the transmission of the node.…”

Analysis and optimisation of heterogeneous real-time embedded systems

“…token ring protocol [44] . fibre distributed data interface protocol [45] . time-triggered protocol [46] .…”