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Network Hardware

Explore the world of network hardware and its impact on productivity. Learn about Ethernet technology, cable mediums like UTP, and ways to connect and expand Ethernets using hubs, switches, and routers. Proper installation and documentation are key. Stay ahead of the rapidly evolving tech landscape!

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Network Hardware

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  1. Network Hardware Chapter 15

  2. Introduction • Nothing is influencing our culture today more than the ability to move large amounts of data from one place to another very quickly. • We now have world-wide connectivity at a level that only die-hard sci-fi fanatics would have dreamed of just a few years ago. • Behind all of this craziness is fancy network hardware and - you guessed it - a whole bunch of stuff that originated in the deep dark caves of UNIX Chapter 15 - Network Hardware

  3. Introduction • Keeping up with these fast-moving bits is a challenge. • The speed and reliability of your network has a direct effect on your organization’s productivity. • A poorly designed network is a personal and professional embarrassment. • It can be very expensive to fix Chapter 15 - Network Hardware

  4. Introduction • At least three major factors contribute to a successful installation: • Development of a reasonable network design • Selection of high-quality hardware • Proper installation and documentation. Chapter 15 - Network Hardware

  5. 1. LAN, WAN, or MAN? • Introduction: • We’re lucky, in a sense, that TCP/IP can be easily transported over a variety of media. • In reality, however, the network market is split into a variety of confusing classifications • LAN - within a building (or group of) • WAN - geographically dispersed • MAN - Metropolitan Area Network Chapter 15 - Network Hardware

  6. 2. Ethernet: The Common LAN • Introduction: • Having captured over 80% of the worldwide LAN market, Ethernet can be found just about everywhere in its many forms. • It started as Bob Metcalf’s Ph.D. at MIT • He graduated, and went to Xerox PARC • Xerox, together with DEC and Intel, eventually developed Ethernet into a product. Chapter 15 - Network Hardware

  7. 2. Ethernet: The Common LAN Chapter 15 - Network Hardware

  8. 2. Ethernet: The Common LAN • How Ethernet works • Ethernet can be described as a polite dinner party at which guests don’t interrupt each other but rather wait for a lull in the conversation before speaking. • If two guests start to talk at once (a collision) they both stop, excuse themselves, wait a bit, and then one of them starts talking again. Chapter 15 - Network Hardware

  9. 2. Ethernet: The Common LAN • How Ethernet works • The technical term for this scheme is CSMA/CD • Carrier Sense - you can tell whether anyone is talking • Multiple Access - everyone can talk • Collision Detect - you know when you interrupt someone Chapter 15 - Network Hardware

  10. 2. Ethernet: The Common LAN • Ethernet topology • The Ethernet topology is a branching bus with no loops (acyclic graph) • Ethernet provides a mechanism to exchange three types of packets on a segment • unicast • multicast • broadcast Chapter 15 - Network Hardware

  11. 2. Ethernet: The Common LAN • Unshielded twisted pair • UTP is the preferred cable medium for Ethernet • It s based upon a star topology and has several advantages over other media: • It uses inexpensive, readily available copper wire • UTP is much easier to install and debug than coax or fiber • Custom lengths are easily made. • UTP uses RJ-45 connectors which are cheap, reliable, and easy to install. • The link to each machine is independent (and private!) Chapter 15 - Network Hardware

  12. 2. Ethernet: The Common LAN • Unshielded twisted pair Chapter 15 - Network Hardware

  13. 2. Ethernet: The Common LAN • Unshielded twisted pair • Category of wires • Category 1 - (and 2) cables are suitable only for voice applications (if that) • Category 3 - the standard for 10 Mb/s (and voice) • Category 4 - 16 Mb/s token ring • Category 5 - support 100 Mb/s • Category 5E (and 6) support 1 Gb/s Chapter 15 - Network Hardware

  14. 2. Ethernet: The Common LAN • Connecting and expanding Ethernets • Ethernets can be logically connected at several points in the seven layer ISO network • Layer 1 - physical layer - repeaters (hubs) • Layer 2 - data link layer - switches • Layer 3 - network layer - routers Chapter 15 - Network Hardware

  15. 2. Ethernet: The Common LAN • Connecting and expanding Ethernets • Hubs and Concentrators • Hubs are active devices that connect physical segments in UTP Ethernet networks. (They require external power) • Acting as a repeater, a hub retimes and reconstitutes Ethernet frames but does not interpret them • The two farthest points ona network must never be more than 4 hubs apart (10 Mb/s) • 100 Mb/s allows 2 • 1000BaseT allows 1 Chapter 15 - Network Hardware

  16. 2. Ethernet: The Common LAN • Connecting and expanding Ethernets • Switches • Their purpose is to join two different physical networks in a way that makes them seem like one big physical network. • They do not require software, but rather receive, regenerate, and retransmit packets in hardware (therefore do not have the repeater limits) Chapter 15 - Network Hardware

  17. 2. Ethernet: The Common LAN • Connecting and expanding Ethernets • Switches (cont) • Most switches use a dynamic learning algorithm to determine where to forward packets. • The goal is only to those that need it. • Switches keep getting smarter as more functionality is built into their firmware. • Some can be used to monitor security by recording any foreign Ethernet address they receive. Chapter 15 - Network Hardware

  18. 2. Ethernet: The Common LAN • Connecting and expanding Ethernets • Switches (cont) • Large sites can benefit from switches that can partition their ports (through software) into subgroups called Virtual Local Area Networks (VLANs) • A VLAN is a group of ports that belong to the same logical segment. • Such partitioning increases the ability of the switch to isolate traffic -- which helps security and performance. Chapter 15 - Network Hardware

  19. 2. Ethernet: The Common LAN • Connecting and expanding Ethernets • Routers • Routers are dedicated computers-in-a-box that contain two or more network interfaces and direct traffic at the network layer (layer 3) • They shuttle packets based upon the information in the TCP/IP protocol headers. • They also packet filter. • Hardware interfaces of many types (FDDI, Ethernet, ATM, …) can be found in a single router Chapter 15 - Network Hardware

  20. 2. Ethernet: The Common LAN • Connecting and expanding Ethernets • Routers (cont) • Depending on your reliability needs and expected traffic load, a dedicated router may or may not be cheaper than a UNIX system configured to at as a router. • However a dedicated router will usually provide superior performance and reliability. • Spend the extra money and avoid the headaches if you are growing… Chapter 15 - Network Hardware

  21. 3. FDDI: The Disappointing and Expensive LAN • Introduction • Fiber Distributed Data Interface (FDDI) was marketed as a 100Mb/s token ring. • It once looked like it would be the easy solution to may organization’s bandwidth needs. • FDDI has been a disappointment • Cost - interfaces were around $10,000 • Performance was terrible. Chapter 15 - Network Hardware

  22. 3. FDDI: The Disappointing and Expensive LAN • Introduction (cont) • The FDDI standard specifies a 100 Mb/s token passing dual ring Chapter 15 - Network Hardware

  23. 4: ATM: The Promised (but sorely defeated) LAN • Introduction • ATM stands for Asynchronous Transfer Mode • or Another Technical Mistake • ATM is mostly dead - except in the WAN environment where large telco corporations are still trying to leverage their misguided investments in ATM hardware. Chapter 15 - Network Hardware

  24. 5. FRAME Relay: The Sacrificial WAN • Introduction • Frame relay is a WAN technology that offers packet-switched data service, usually for a reasonable cost. • Frame relay connections have some packet switching overhead, and link speed may degrade during periods of heavy use. Chapter 15 - Network Hardware

  25. 6. ISDN: The Indigenous WAN • Introduction • Integrated Services Digital Network (ISDN) is a phone company offering that takes many forms. • In its most common form, ISDN is essentially an all digital phone line that provides two dial up (64Kb/s) channels and one (16Kb/s) signaling channel. • You need interfaces (like modems) at each end. Chapter 15 - Network Hardware

  26. 7. DSL: The People’s WAN • Introduction • Digital Subscriber Line (DSL) uses ordinary copper telephone wire to transmit data at speeds of up to 7 Mb/s (256 Kb/s to 768 Kb/s is more typical) • This is the preferred technology for homes. • It is a dedicated network service that is always connected. • The race for “last mile” connectivity to hundreds of millions of homes is a hot one • The other option is cable. Chapter 15 - Network Hardware

  27. 8. Where is the Network going? • Introduction • The simple inexpensive technologies are succeeding and the complex expensive ones are dying. • Ethernet has pummeled its rivals because it is incredibly inexpensive. • Another exciting area of development is wireless networking. • Debugging a wireless network is something of a black art. • And TCP/IP runs on it all…. Chapter 15 - Network Hardware

  28. 9. Network Testing and Debugging • Introduction • One major advantage of the large scale migration to Ethernet is the ease of network debugging. • Since these networks can be analyzed link by link, hardware problems can often be isolated in seconds rather than days. • Having the right tools for the job is a big part of being able to get the job one. • The first is a hand-held cable analyzer. • The second is a network sniffer. Chapter 15 - Network Hardware

  29. 10. Building Wiring • Introduction • Whether you’re running gigabit Ethernet or just serial cables, we recommend that you use the highest possible quality of wire. • It will increase the chances that you can still use the same wire 10 years down the road Chapter 15 - Network Hardware

  30. 11. Network Design Issues • Introduction: • Most of network design consists of the specification of: • The types of media that will be used. • The topology and routing of cables • The use of repeaters, bridges, and routers. • Another key issue in network design is congestion control. Chapter 15 - Network Hardware

  31. 12. Management Issues • Introduction: • If the network is to work correctly, some things need to be centralized, some distributed, some local. • A typical environment includes • A backbone network among buildings • Departmental subnets connected to the backbone • Group subnets within a department • Connections to the outside world Chapter 15 - Network Hardware

  32. 12. Management Issues • Introduction: • Prime targets for central control are: • The network design, including the use of subnets, routers, switches, etc. • The backbone cable itself, including connections to it. • Host IP addresses, hostnames, and subdomain names. • Protocols • Routing policy to the internet. Chapter 15 - Network Hardware

  33. 14. Recommended Reading • Groth, David and Jim McBee. Cabling: The Complete Guide to Network Wiring. Sybex 2000. • Seifert, Rich. Gigabit Ethernet. Reading, MA: Addison-Wesley. 1998. Chapter 15 - Network Hardware

  34. Chapter 15 - Network Hardware

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