|
Unit Contents
Overview 
Local area network (LAN) and wide area network (WAN) protocols are the ones used to get information into the node so it can, in turn, be delivered to the processes at the higher layers. In that regard, these protocols are normally less complex than those above it. For example, one may find headers consisting of more than 10 fields to accommodate Transmission Control Protocol (TCP) functionality because of the various services offered by the Transport Layer. On the other hand, the function of Data Link Layer protocols is essentially limited to local, group, and broadcast address recognition and certain basic error checking, as implemented in the Frame Check Sequence. Additionally, there are both connection-oriented and connectionless modes of operation available. These protocols get information, in the form of frames, from one point, across a link, to the next point in the network. In a LAN environment, this would be from a network interface card (NIC) across the physical media to another NIC. In a WAN environment, the protocols get information across a longer distance from router-to-router, normally using public facilities, such as copper telephone lines and fiber optic links.
[ Previous Unit ] [ Next Section ]
 |
