Question

1. Explain how rules are used to facilitate communication.

2. Explain the role of protocols and standards organizations in facilitating interoperability in network communications.

3. Explain how devices on a LAN access resources in a small to medium-sized business network.

Answer 1

1. Explain how rules are used to facilitate communication.

 All communication methods have three elements in common:

• Source or sender • Destination or receiver • Channel or media

 Rules or protocols govern all methods of communication.

Rule Establishment:

Protocols are necessary for effective communication and include:

• An identified sender and receiver

• Common language and grammar

• Speed and timing of delivery

• Confirmation or acknowledgment requirements

 Protocols used in network communications also define:

• Message encoding

• Message delivery options

• Message Formatting and Encapsulation

• Message Timing

• Message Size

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2. Explain the role of protocols and standards organizations in facilitating interoperability in network communications.

Rules that Govern Communications

 Protocol suites are implemented by hosts and networking devices in software, hardware or both.

 The protocols are viewed in terms of layers, with each higher level service depending on the functionality defined by the protocols shown in the lower levels.

Network Protocols

 Networking protocols define a common format and set of rules for exchanging messages between devices.

 Some common networking protocols are Hypertext Transfer Protocol (HTTP), Transmission Control Protocol (TCP), and Internet Protocol (IP).

Protocol Interaction

 Communication between a web server and web client is an example of an interaction between several protocols:

• HTTP - an application protocol that governs the way a web server and a web client interact.

• TCP - transport protocol that manages the individual conversations.

• IP – encapsulates the TCP segments into packets, assigns addresses, and delivers to the destination host.

• Ethernet - allows communication over a data link and the physical transmission of data on the network media.

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3. Explain how devices on a LAN access resources in a small to medium-sized business network.

Message Segmentation:

 Large streams of data are divided into smaller, more manageable pieces to send over the network. • By sending smaller pieces, many different conversations can be interleaved on the network, called multiplexing. • Each piece must be labeled. • If part of the message fails to make it to the destination, only the missing pieces need to be retransmitted.

Protocol Data Units:

As application data is passed down the protocol stack, information is added at each level. This is known as the encapsulation process.  The form that the data takes at each layer is known as a Protocol Data Unit (PDU). • Data - application layer PDU • Segment – Transport layer PDU • Packet – Network layer PDU • Frame – Data Link Layer PDU • Bits – Physical Layer PDU

1. Data Access: (Network Address)

 Network layer source and destination addresses - Responsible for delivering the IP packet from the original source to the final destination. • Source IP address - The IP address of the sending device, the original source of the packet. • Destination IP address - The IP address of the receiving device, the final destination of the packet.

2. Data Link Address

The purpose of the data link address is to deliver the data link frame from one network interface to another network interface on the same network. • As the IP packet travels from source to destination it is encapsulated in a new data link frame when it is forwarded by each router.

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