An Investigation into Transport Protocols and Data Transport ...

A.2. Network Interface Cards 274
Layer 2 of the ISO/OSI model and Layer 1 of the TCP/IP network model.
Typically, most NICs are Ethernet (IEEE 802.3) based [MB76] due to its
low cost. It is also worth noting that the interconnects used to construct
the Layer 1 communications are also cheap - utilising twisted-pair copper
cabling 3 . The viability of utilising Ethernet as a generic hardware networking
solution is also increasing as computer hardware manufacturers and suppliers
have also been integrating NICs into their products as standard.
As defined in the OSI and TCP/IP models, the NIC provides the base
and hence limiting factor in the communication speeds between networked
devices. It is therefore important to benchmark the performance at which
data can be physically and logically placed into the network.
A.2.1
Test Methodology
As the NIC is the primary subsystem that communicates data into a format
which can be sent over any network, it is important to investigate its performance
without the intervention of Routing and Switching which may impose
further bottlenecks/performance deterioration.
The performance of a Network Interface Card is defined as follows:
Speed The absolute rate at which data can be transmitted to and from the
NIC. Due to header size constraints and the relation between the packet
sizes used and overhead required per packet, smaller packet sizes are
more likely to cause a performance burden.
Latency The amount of time that it takes for the system to transmit a
packet. More importantly, the change in latency with packet size can
3 More expensive fibre optic based Ethernet cards are also available.