Network2/Concept/Link

A link is a network of nodes in which every pair of nodes can exchange messages via interfaces attached to media. Frequently, links are made to encompass more nodes by bridging two or more distinct media, e.g. as is done with wired switches, wired hubs, multi-channel wireless access points, or with the physical bridges and tunnels that connect road networks separated by water or mountains.

Links are characterized by their:

• capacity, latency, jitter, and error characteristics
• support (or lack thereof) for efficient unicast, multicast, or broadcast message propagation
• media access control (MAC) protocol, which participating interfaces use to reduce the frequency of message collisions
• framing protocol, which participating interfaces use to detect message boundaries and to encapsulate other protocols' messages for transport
• maximum transmission unit (MTU), which is the size of the largest single message that the link can propagate

and by what kind of message they carry.