Topic1-Part I Modules1-5.pdf

Part I Network Fundamentals 1 Part I Module 1: Networking Fundamentals 1.1 Network Terminology 3 Sneakernet, also called sneaker net, is an informal term for the transfer of electronic information by physically moving media such as magnetic tape, floppy disks, optical discs, USB flash drives or exte...

Part I Network Fundamentals 1 Part I Module 1: Networking Fundamentals 1.1 Network Terminology 3 Sneakernet, also called sneaker net, is an informal term for the transfer of electronic information by physically moving media such as magnetic tape, floppy disks, optical discs, USB flash drives or external hard drives between computers, rather than transmitting it over a computer network. The term, a tongue-in-cheek play on net(work) as in Internet or Ethernet, refers to walking in sneakers as the transport mechanism. Sneakernet 4 Data networks 5 LAN (how to define LAN?) 6 LAN 7 WAN (WAN = Internet?) 8 Examples of data networks 9 Networking devices 10 Repeater 11 Bridge Details will be covered in module 8.1.1 Layer 2 bridging 12 Swtich 13 Network topology 14 The diagram shows many different topologies connected by network devices. It shows a network of moderate complexity that is typical of a school or a small business. 15 16 A real network topology of a University in HK Network protocols A protocol is a formal description of a set of rules and conventions that govern a particular aspect of how devices on a network communicate. Protocols determine the format, timing, sequencing, and error control in data communication. organizations and committees: the Institute of Electrical and Electronic Engineers (IEEE), American National Standards Institute (ANSI), Telecommunications Industry Association (TIA), Electronic Industries Alliance (EIA) International Telecommunications Union (ITU) 17 Storage-area networks (SANs) SAN is a dedicated, high-performance network used to move data between servers and storage resources. Because it is a separate, dedicated network, it avoids any traffic conflict between clients and servers. SAN technology allows high-speed server-to-storage, storage-to-storage, or server-to-server connectivity. This method uses a separate network infrastructure that relieves any problems associated with existing network connectivity. 18 Network Attached Storage (NAS) NAS devices are storage arrays or gateways that support file-based storage protocols such as NFS and CiFS, and are typically connected via an IP network. These file-based protocols provide clients shared access to storage resources. This centralization of shared storage resources reduces management complexity, minimizes stranded disk capacity, improves storage utilization rates and eliminates file server sprawl. 19 NAS vs SAN The primary difference between NAS and SAN solutions is the type of access protocol. NAS protocols such as NFS and CiFS provide shared file level access to storage resources. The management of the file system resides with the NAS device. SAN protocols such as iSCSI and fibre channel provide block level access to storage resources. Block level devices are accessed by servers via the SAN, and the servers manage the file system. 20 https://youtu.be/3yZDDr0JKVc Virtual private network (VPN) A VPN is a private network that is constructed within a public network infrastructure such as the global Internet. Using VPN, a telecommuter can remotely access the network of the company headquarters. Through the Internet, a secure tunnel can be built between the PC of the telecommuter and a VPN router at the company headquarters. 21 1.2 Bandwidth 22 22 Importance of bandwidth Why bandwidth is important: – – – – Bandwidth is limited by physical and technology Bandwidth is not free Bandwidth requirements are growing at a rapid rate Bandwidth is critical to network performance 23 Pipe Analogy for Bandwidth 24 Highway Analogy for Bandwidth 25 2.2.3 Units of Bandwidth 26 Maximum Bandwidths and Length Limitations 27 WAN Services and Bandwidths 28 Throughput Throughput – The measure of the transfer of bits across the media over a given period of time – B B ->A A->C D->C 105 Layer 2 switching A bridge has only two ports and divides a collision domain into two parts. A bridge will divide a collision domain but has no effect on a broadcast domain. A switch is essentially a fast, multi-port bridge. Each port creates its own collision domain. 106 Switch Operation 107 Full Duplex 108 Network Latency 109 Cut-Through Store-and-Forward 110 Spanning-Tree Protocol 111 5.2 Collision Domains and Broadcast Domains 112 112 Shared media environments 113 Collision domains 114 Collision Domain Segmentation 115 Layer 1 devices extend collision domains Limiting the collision domain 116 Segmenting a collision domain with a bridge 117 Layer 3 Broadcasts Broadcasts in a bridged environment 118 119 Broadcast domains segmentation 120 What is a network segement? Network segment: Section of a network that is bounded by bridges, routers, or switches. 121