March 21, Tetra 4D 3d Pdf Converter 35 Crack March 19, March 17, Table of Contents. Behrouz A. Chegg Study. Unlike static PDF.. Look Up Quick Results Now! Questions testbanklive. At the network layer, the unit of data is a datagram. At the data-link layer, the unit of data is a frame. A frame is a link-layer data unit. It encapsulates a data unit coming from the network layer.
In this case, the data unit is a datagram. A user datagram is a transport-layer data unit. It decapsulates a data unit going to the application layer. In this case, the data unit is a message. The data unit should belong to layer 4. In this case, it is a user datagram. The transport-layer packet needs to include two port numbers: source and destination port numbers.
The transport-layer header needs to be at least 32 bits four bytes long, but we will see in Chapter 24 that the header size is normally much longer because we need to include other pieces of information.
At the application layer, we normally use a name to define the destinationcomputer name and the name of the file we need to access.
An example is [email protected] b. At the network layer, we use two logical addresses source and destination to define the source and destination computers. These addresses are unique universally.
At the data-link layer, we use two link-layer addresses source and destination to define the source and destination connections to the link. The answer is no. It only means that each of the transport-layer protocols such as TCP or UDP can carry a packet from any application-layer protocol that needs its service. However, a transport-layer packet can carry one, and only one, packet from an application-layer protocol. We do not need a link-layer switch because the communication in this case is automatically one-to-one.
A link-layer switch is needed when we need to change a one-to-many communication to a one-to-one. We do not need a router in this case because a router is needed when there is more than one path between the two hosts; the router is responsible for choosing the best path at each moment.
Problems P The services provided in part a and part b are the opposite of each other. Layer 1 takes the ciphertext from layer 2, inserts encapsulates it in an envelope and sends it.
Layer 1 receives the mail, removes decapsulates the ciphertext from the envelope and delivers it to layer 2. Layer 2 takes the plaintext from layer 3, encrypts it, and delivers it to layer 1. Layer 2 takes the ciphertext from layer 1, decrypts it, and delivers it to layer 3.
In 10 years, the number of hosts becomes about six times 1. This means the number of hosts connected to the Internet is more than three billion. The system transmits bytes for a byte message. The advantage of using large packets is less overhead. When using large packets, the number of packets to be sent for a huge file becomes small. Since we are adding three headers to each packet, we are sending fewer extra bytes than in the case in which the number of packets is large.
The disadvantage manifests itself when a packet is lost or corrupted during the transmission; we need to resend a large amount of data. The network layer is responsible for route determination.
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