Q1-1) Identify the five components of a data communications system. 1.Message.
Q1-11) Why are protocols needed?
To achieve end-to-end delivery of data.
Q-17) Explain the difference between an Internet draft and a proposed standard? - An Internet draft is a working document (a work inprogress) with no official status and a six- month lifetime. - A proposed standard is elevated to draft standard status after atleast two successful independent and interoperable implementations. Q2-5) A host communicates with another host using the TCP/IP protocol suite. What is the unit of data sent or received at each of the following layers? a. application layer:Message b. network layer:Datagram c. data-link layer:Frame
Q2-12) When we say that the transport layer multiplexes and demultiplexes application layer messages, do we mean that a transport-layer protocol can combine several messages from the application layer in one packet? Explain. The TCP/IP protocol suite uses several protocols at some layers, we can say that we have multiplexing at the source and demultiplexing at the destination. Multiplexing in this case means that a protocol at a layer can encapsulate a packet from several next-higher layer protocols (one at a time); demultiplexing means that a protocol can decapsulate and deliver a packet to several next-higher layer protocols (one at a time). To be able to multiplex and demultiplex, a protocol needs to have a field in its header to identify to which protocol the encapsulated packets belong. At the transport layer, either UDP or TCP can accept a message from several application-layerprotocols. At the network layer, IP can accept a segment from TCP or a user datagram from UDP. IP can also accept a packet from other protocols such as ICMP, IGMP, and so on. At the data-link layer, a frame may carry the payload coming from IP or other protocols such as ARP....
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