There exist different modes of failures for communication channels in the literature.
Section 2.3 presents a similar classification of failure modes for processes that can be adapted to
communication channels. As shown in 2.5, crash failures are included in omission failures, which are
included in arbitrary failures.
Figure 2.5: Failure modes of a communication channel, by [GR06].
Crash: in case of a crash of a communication channel, the latter is down and stops
transmitting messages.
Channel omission failure: it corresponds to a message loss in a communication channel,
i.e. failing to transmit the message from the outgoing buffer to the incoming one.
Arbitrary failures: for communication channels, arbitrary failures include messages
corruption, messages omission, messages creations or multiple message deliveries. Some
arbitrary failures in communication channels can be detected and fix by using error
detection and correction, such as checksums or cyclic redundancy checks (CRC). Therefore, information exchanged by processes on communication channels is not reliable
anymore, and security steps may be then required.
The different modes of failure are summarized in the following 2.4.
Table 2.4: Table of failure modes of communication channels.
Failures
Component
Description
Crash
Channel
Stops transmitting messages.
Channel omission
Channel
Message loss.
Arbitrary/Byzantine
Channel
Arbitrarily corrupts, omits, creates or delivers message.