Basic Trunk Principles
The member links of a trunk link can be configured with different weights to carry out load balancing, which helps ensure connection reliability and greater bandwidth.
Users can configure trunk interfaces to support various routing protocols and services.
Figure 1 shows a simple Eth-Trunk example in which two routers are directly connected through three interfaces. These three interfaces are bundled into an Eth-Trunk interface at both ends of the trunk link. In this way, the bandwidth is increased, and reliability is improved.
A trunk link can be considered as a point-to-point link. The devices on the end the link can be both routers or switches, or a router on one end and a switch on the other.
A trunk has the following advantages:
Greater bandwidth
The total bandwidth of a trunk interface equals the sum of the bandwidth of all its member interfaces. In this manner, the interface bandwidth is multiplied.
Higher reliability
If a member interface fails, traffic on the faulty link is then switched to an available member link. This ensures higher reliability for the entire trunk link.
Load balancing
Load balancing can be carried out on a trunk interface, which distributes traffic among its member interfaces and then transmits the traffic through the member links to the same destination. This prevents network congestion that occurs when all traffic is transmitted over one link.