4 / 10 Clocks, Ordering & Causality

Causal Broadcast Delivery Condition

In a causal broadcast protocol using vector clocks, process PiP_i receives a message mm from PjP_j with attached vector clock VC(m)VC(m). Under what condition does PiP_i deliver mm immediately rather than buffering it?

A

VC(m)[j]=VCi[j]+1VC(m)[j] = VC_i[j] + 1 only; other components do not matter

B

VC(m)[j]=VCi[j]+1VC(m)[j] = VC_i[j] + 1 and VC(m)[k]≤VCi[k]VC(m)[k] \leq VC_i[k] for all k≠jk \neq j

C

VC(m)[j]>VCi[j]VC(m)[j] > VC_i[j] and VC(m)[k]≥VCi[k]VC(m)[k] \geq VC_i[k] for all k≠jk \neq j

D

VC(m)>VCiVC(m) > VC_i componentwise