In the post Introduction to Basic Interface Attributes we learned about the ethernet interface in this post I want to comment about the trunk interfaces.
Trunks bind multiple physical interfaces together into a single logical interface, called a trunk interface. The bound physical interfaces are called member interfaces.
Trunk technology can increase the bandwidth, enhance reliability, and help implement load balancing.
Without using trunk technology, the transmission rate between two network devices connected by fast Ethernet twisted pair cables is limited to 100 Mbit/s. Higher transmission rates can be achieved by changing the transmission media and replacing twisted pair cables with gigabit fiber cables, or upgrading the existing network to a Gigabit Ethernet network. These solutions, however, are costly and not suitable for small-and-medium size enterprises or institutions.
Therefore, trunk technology is an economical solution, which by binding multiple interfaces together, can increase interface bandwidth and achieve a higher transmission rate. For example, three 100 Mbit/s full-duplex interfaces can be bound together to provide a maximum bandwidth of 300 Mbit/s.
What is more, the trunk technology ensures the binding of not only Ethernet interfaces but also Packet Over SONET/SDH (POS) interfaces. Ethernet interfaces and POS interfaces, however, cannot be bound into the same trunk interface.
References
IEEE 802.3ad
