There are two kinds of machines in a Cedar Backup pool. One machine (the master) has a CD or DVD writer on it and writes the backup to disc. The others (clients) collect data to be written to disc by the master. Collectively, the master and client machines in a pool are called peer machines.
Cedar Backup has been designed primarily for situations where there is a single master and a set of other clients that the master interacts with. However, it will just as easily work for a single machine (a backup pool of one) and in fact more users seem to use it like this than any other way.