New technologies like fiber-optics made possible networks offering increasing
transmission capacity at decreasing error rates. This change in technology
has to be taken into consideration when designing new protocols for data
transmission so that applications can use this bandwidth effectively.
Transport protocols should offer the applications not only a reliable data
transmission, but also a service that allows the application to react in
a flexible way when data is lost.
The instruction paths, particularly at the receiver's end, should be kept
as short as possible and timers should be employed only when necessary.
In packet-switched networks, a rate control can reduce congestion and consequently
packet loss caused by network overload.
The objective of this semester thesis was to design and implement a transport protocol that uses ATM Adaptation Layer 5 and allows the applications to react in a flexible manner in case of data loss.
The application programming interface of the developed transport protocol
allows the receiving application to read packets which have already been
received by the transport protocol sequentially (reliable data transmission)
or, within certain limits, in any order.
In case of packet loss, the application can decide whether the packet should
be retransmitted or cancelled. This flexible reaction to data loss requires
the application to be able to cope with out-ot-order delivery of data.
On the sender's side the application can choose whether it advises the transport
protocol to buffer unacknowledged packets or if a packet's contents shall
be recalculated in case of packet loss.
The transport protocol employs selective retransmission and negative acknowledgement.
Flow control is done by a credit-based window mechanism. Rate control has
not been implemented yet, but considered in the protocol's design.
snail mail: Daniel Brennwalder, Seebühlstr. 26, CH-8472 Seuzach,
Switzerland
e-Mail: dbrennwa@iiic.ethz.ch