Storage Networking Architectures
Parallel Bus Basics
• Faster transmission speeds increase skew
– Speed is increased by adding connections and
speeding up the clock rate
– Extra connections = more opportunity for skew
– Faster signaling = smaller time windows
– Maximum distance decreases
The skew problem gets worse as transmission speeds increase:
To meet the demand for faster and faster data transfer, the parallel bus
approach has been to double or quadruple the connections and speed
up the clock rate.
Extra connections mean that there is more opportunity for the individual
signals to get out of time with each other.
Faster signalling speed means that there are tighter time windows in
which a signal must arrive.
This effect means that as the speeds increase, maximum length of the
bus must be reduced to compensate for the increased skew effect.