4. link layer encapsulates the datagram received from the network layer into a frame?
In order for a datagram to be transferred from source host to destination host, it must be moved over each of the individual links in the end-to-end path. Over a given link, a transmitting node encapsulates the datagram in a link-layer frame and transmits the frame into the link; the receiving node then receives the frame and extracts the datagram.
A link-layer protocol is used to move a datagram over an individual link. The link-layer protocol defines the format of the packets exchanged between the nodes at the ends of the link, as well as the actions taken by these nodes when the packets are sent and received. The units of data exchanged by a link-layer protocol are called frames, and that each link-layer frame typically encapsulates a network-layer datagram. The actions taken by a link-layer protocol when sending and receiving frames …show more content…
What operations does the link layer and physical Layer support? https://web.cs.wpi.edu/~cs4514/b98/week3-dll/week3-dll.html Operations of link layer and physical layer support
Although the basic service of any link layer is to move a datagram from one node to an adjacent node over a single communication link, the details of the provided service can vary from one link-layer protocol to the next. Possible services that can be offered by a link-layer protocol include:
Framing:
Almost all link-layer protocols encapsulate each network-layer datagram within a link-layer frame before transmission over the link. A frame consists of a data field, in which the network-layer datagram is inserted, and a number of header fields. (A frame may also include trailer fields; however, we will refer to both header and trailer fields as header fields.) The structure of the frame is specified by the link-layer protocol. We'll see several different frame formats when we examine specific link-layer protocols in the second half of this section.
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