Lecture 5 - Network Devices

-

Introduction to Network Devices

1. Repeater:

- It is a double pot device that regenerate the signal before the signal becomes too weak or corrupted by coping it bit by bit.

- It does not amplify the signal.


2. Hub:

- It is multiport repeater which connects multiple wires coming from different branches.

- It doesn't filter data, so data packets are sent to all connected devices causing collision domain, inefficiencies and wastage.

Types of Hub:

1. Active Hub: have their own power supply, can clean, boost, and relay the signal along with the network and used to extend the maximum distance between nodes.

2. Passive Hub: have power supply from the active hub, relay signals onto the network, cleaning, boosting and can’t be used to extend the distance between nodes.

3. Intelligent Hub: works like active hubs and also has remote management capabilities. It provides flexible data rates to network devices and enables an administrator to monitor and to configure the traffic passing through the hub.

3. Switches:

- A switch is multiport bridge which can boost its efficiency, check error, and forward packets selectively to the correct port only.

- It causes no collision domain, but the broadcast domain remains the same.


4. Router:

- It is a device like a switch that routes data packets based on their IP addresses.

- Router divide broadcast domains of hosts connected through it.

               



Network switches

Steps of switch operation:

1. The switch receives a frame.

2. The switch reads the source and destination MAC addresses.

3. The switch looks up the destination MAC address in its switching table.

4. The switch forwards the frame to the port where the computer owning the MAC address is found.

5. The switching table is updated with the source MAC address and port information.


NICs and MAC Address

MAC address is stored in read-only memory (ROM) on the NIC.

24-bit hexadecimal numbers manufacturer ID called OUI.

24-bit serial number assigned by the manufacturer.


NICs as Gatekeeper

When a frame arrives at a NIC, the NIC check’s the frame’s destination MAC address.

When the destination MAC address matches the MAC burned-in address (BIA), or the physical address of a NIC, it’s a unicast frame.

When the destination is the broadcast address, it’s a broadcast frame which are intended to be processed by all computers on the network.

Promiscuous mode: turns off the gatekeeper functions and enables the NIC to process all frames.


Indicator lights in NIC

The link light is usually green when the NIC has a valid connection to the network color.

Some NICs support multiple speeds, therefore is usually a separate light for each speed or light of different color so that you can determine at what speed the NIC is connected to the hub or switch.


Routers Work with IP Addresses and Routing Tables

Default route: where to send a packet when the router doesn’t have an entry in its routing table.

Default gateway: In a computer’s IP address configuration, the IP address of the computer’s router.

Network unreachable: Message sent when the network can’t be found and no default route.

Comments

Post a Comment

Popular posts from this blog

Lecture 2 - Fetch, Execution and IO

-
  Data is stored in Bits 1 byte = 8 bits Bit - the smallest unit of data measurement in computer.       - it can be either 0 or 1. Pulse of 5 volts of electricity = 1bit Pulse of 0 volts of electricity = 0 1 bit - presence of light 0 bit - absence of light A "byte" is a collection of 8 bits. Functional units 1. Primary memory (main memory) - Organized into words of typically 32 bits (contains four 8-bit bytes) - Programs and their data must be in memory to be executed. 2. Cache memory (smaller and faster than main memory) - Holds sections of the program and data currently/frequently being executed. 3. Processor - Logic circuits: for performing arithmetic and logic operations on word-size data operands. - Timing and control circuits: for fetching program instructions and data from memory, one after another. - Registers (typically 16 or 36): holds one word of operand data sections of the program and data currently/frequently being executed.   Computer - Computer...
Read more

Lecture 11 Linux Network and Process Management

-
Image
  Process In Linux, a process is a currently executing program, representing an instance of a program managed by the Linux kernel. Every process is distinguished by a specific Process ID (PID) and possesses its own allocated resources, including memory and CPU time. Process States Process States in a System: Running : Actively executing code. Ready : Awaiting CPU time to run. Sleeping : Paused, pending an event or resource. Stopped : Halted intentionally by user or the system. Zombie : Process finished, but still listed in the process table. Process Management Commands for Managing Processes in Linux: ps : Displays a snapshot of the current processes.             Example: ps ps  aux: Shows detailed information about all processes.             Example: ps aux ps aux | grep username : Filters processes by a specific username.             Example:...
Read more

Lecture 12 Clint Server Architecture

-
Image
  Introduction The client-server architecture is a framework for computer networks where numerous clients, acting as remote processors, seek and obtain services from a central server or host computer.  Clients serve as interfaces, enabling computer users to solicit services from the server and showcase the outcomes returned by the server. Servers, in turn, anticipate incoming requests from clients and subsequently fulfill them with appropriate responses. Client  – The client can be any computer that requests something from the server. For example – visiting any website we request the webpage from its domain. So here we act as a client. Server  – On the other hand, the Server is the computer that is designed to serve the requests to the client. For the same example as above, the client asks for the webpage then the server responds with the webpage to the client. Working of Client-Server Architecture when a client seeks data from a server, it initiates the process by q...
Read more