Network Hardware Chapter 15 Network Hardware Introduction n

Network Hardware Chapter 15 - Network Hardware

Introduction n Nothing is influencing our culture today more than the ability to move large amounts of data from one place to another very quickly. n 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. n 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 Chapter 15 - Network Hardware UNIX

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

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

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

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

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

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

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

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

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

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

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

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

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

2. Ethernet: The Common LAN n Connecting and expanding Ethernets n Switches n Their purpose is to join two different physical networks in a way that makes them seem like one big physical network. n 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

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

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

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

2. Ethernet: The Common LAN n Connecting and expanding Ethernets n Routers (cont) n 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. n However a dedicated router will usually provide superior performance and reliability. n Spend the extra money and avoid the headaches if you are growing… Chapter 15 - Network Hardware

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

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

4: ATM: The Promised (but sorely defeated) LAN n Introduction n ATM stands for Asynchronous Transfer Mode n or Another Technical Mistake n 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

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

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

7. DSL: The People’s WAN n 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) n This is the preferred technology for homes. n n It is a dedicated network service that is always connected. n The race for “last mile” connectivity to hundreds of millions of homes is a hot one n The other option is cable. Chapter 15 - Network Hardware

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

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

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

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

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

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

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

Chapter 15 - Network Hardware