Agreement messages Sample Clauses

Agreement messages. ‌ The protocol has to deal with the fact that there may be a number of messages ‘in flight’ or at least languishing in transmission or reception buffers awaiting processing. The topology (and the accompanying digest) can change and change back again, so the reception of a matching digest in an agreement message is not sufficient to indicate that a protocol partner is not holding additional agreements. Each agreement message, however it is carried in protocol frames, comprises the following parameters: — digest — the agreement digest. — an — the agreement number, drawn from a small circular sequence number space, for subsequent use by the receiver of the message in the xxx xxxxx. — xxx — the discarded agreement number. The ‘discarded agreement number’ identifies the last agreement digest processed by the prior to discarding agreements that contradict or are not a subset of those expressed by the digest. Specifically the transmitted and received digest, an, and xxx, together with the last calculatedDigest identify the following conditions. • txDigest != calculatedDigest The forwarding carried out by the bridge (node) has not yet been reduced to a pattern that is a subset of of that in the topology identified by the calculatedDigest and permitted by outstanding and held agreements. • tx.xxx == rx.an The agreements currently held by the actor are those required by (or a subset of those required by) txDigest and the received message defined by rx.an. In other words txDigest was calculated (and the agreements held filtered by the corresponding topology) after the received message with rx.an was received • tx.xxx == rx.an - 1 The link state calculation identified by txDigest was completed, and conflicting received agreements discarded, prior to receipt of the rxDigest identified by rx.an. In other words the actor may be holding received agreements that conflict with txDigest, though these will be a subset of the union of those permitted by txDigest and those permitted rxDisgest. • tx.xxx == rx.an - 2 The actor may be still holding received agreements that conflict with txDigest since it has not recognized (or completed processing for) any recent digest. If the actor receives additional digests (with incerementing rx.an) that do not match its calculatedDigest it will increment tx.xxx so it continues to lag tx.xxx at rx.an - 2, thus rotating the sequence number so that its partener can send further agreement messages.