Computer Networking Lecture 2 PDF

Network Devices Dr. Enas Elgeldawi Reminder - What is a Computer Network? A computer network is simply two or more computing devices connected together in a way that lets them exchange information and share resources. A computer network is a set of computer...

Network Devices Dr. Enas Elgeldawi Reminder - What is a Computer Network? A computer network is simply two or more computing devices connected together in a way that lets them exchange information and share resources. A computer network is a set of computers sharing resources located on or provided by network nodes. What is a Node? A network node  is a connection point in a communication network. Nodes have capability to send, receive, store, process or create information, and forward transmissions to other network nodes.  is any addressable device connected to a network.  is a connection point in a communications network. Each node is an endpoint for data transmissions or redistribution. Nodes have capability to process, send, receive, store or create information, and forward transmissions to other network nodes. Nodes Examples What is a Node? A network node  is a connection point in a communication network. Nodes have capability to send, receive, store, process or create information, and forward transmissions to other network nodes.  is any addressable device connected to a network.  is a connection point in a communications network. Each node is an endpoint for data transmissions or redistribution. Nodes have capability to process, send, receive, store or create information, and forward transmissions to other network nodes. Hosts / Endpoints Nodes Examples What is a Client? A Client is a device that requests and then accesses a service that is made available by the server What is a Server? A Server is a device that provides functions or services for clients. IBM Server China Telecom Data Center Occupying 10,763,910 square feet and being located in China, this is the world’s largest server room. The DC in Hohhon is recognized to be the greatest facility for datum storage and processing around the world. It saves 50% of the marker datum in China. The facility has over 400 subdivisions around the country; the main facility occupies a territory of 100 hectares. The DC provides cloud computing, telecommunication, and financial services. Such giants of the world market as Alibaba, Tencent, and Baidu utilize their capacities. Client / Server Relationship: Example 1 Client / Server Relationship: Example 1 Client / Server Relationship: Example 1 Client / Server Relationship: Example 1 Client / Server Relationship: Example 2 Client / Server Relationship: Example 2 Client / Server Relationship: Example 3 AirDrop AirDrop The same device can be a client at some situations, and a server in other situations. What is a Switch?  Typically we don’t connect PCs or servers directly to each other, we aggregate the connections to a device called a switch.  A switch has a lot of interfaces (or Ports), usually 24 or more ports, to connect hosts (PCs or servers) to it.  Switches are used to connect LAN devices and forward traffic within the same LAN. However, they can not directly be connected to the internet and send data or provide connectivity between different LANs. Switches TP-Link Netgear JGS524 Switches – Routers – Firewalls Switches – Routers – Firewalls Switches – Routers – Firewalls Switches – Routers – Firewalls Switches – Routers – Firewalls Routers Switches – Routers – Firewalls Switches – Routers – Firewalls Firewalls Switches – Routers – Firewalls Switches – Routers – Firewalls  Switches – Routers – Firewalls  Firewalls are specialty network security devices that control network traffic entering and exiting your network.  Firewalls can be placed ‘outside’ of your router, like FW1, or ‘inside’ of your network, like FW2.  What’s important is that they protect the end hosts inside, like the PCs and Servers in this network.  Firewalls must be configured with security rules to determine which network traffic should be allowed and which should be denied. Switches – Routers – Firewalls  Switches – Routers – Firewalls  If you configure the rules properly, if PC1 in the New York Branch tries to access SRV1 in Tokyo, the firewalls should permit the traffic through.  The return traffic from SRV 1 to PC1 should be allowed as well.  However, if the attacker tries to access anything inside of our networks, the firewall should block it. Firewalls