Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Wake-on-LAN wikipedia , lookup
Power over Ethernet wikipedia , lookup
Asynchronous Transfer Mode wikipedia , lookup
Computer network wikipedia , lookup
Piggybacking (Internet access) wikipedia , lookup
Passive optical network wikipedia , lookup
Cracking of wireless networks wikipedia , lookup
List of wireless community networks by region wikipedia , lookup
Network tap wikipedia , lookup
Network topologies Unit objective Describe different logical and physical network topologies Compare and contrast different LAN technologies Categorize WAN technology types and properties Identify virtual network components Topic A Topic A: Network topologies Topic B: LAN technologies Topic C: WAN technologies Topic D: Virtual networks Local area networks Located within a confined area Connected by wires or radio waves Node: any network device Host: always a computer Can be connected to the Internet Requires host OS Network topologies Networks defined by logical and physical topologies Logical — The path that data takes between nodes Physical — The material layout of network wiring and locations of nodes Logical network topologies Two basic LANs: – Peer-to-peer – Client/server Extend LAN remotely: – Virtual private network (VPN) Peer-to-peer model Simple file and resource sharing Home or small office Computers have: – NIC for wired or wireless connections – Client OS that supports network connectivity; hosts can have different OSs Fewer than a dozen hosts – Client OSs have connection limits Decentralized All hosts have equal authority Each host controls its own resources Individual user responsibility Peer-to-peer authentication User account includes – User name – Password – Permissions User account exists on single computer Valid user credentials for computer use User name and password for authentication, validation, logging on Can create additional user accounts Can share local resources with other users Client/server model Servers hold data and provide services Scales larger than peer-to-peer network Network operating system on server Servers manage resources Unlimited connections NOS provides: – Network directory services – Network security, monitoring, and auditing features – Architectural framework (APIs) to support server-based applications A client/server LAN Client/server authentication Client OS sends login information to directory server Directory server responsible for user authentication Login process — Client communicates with NOS on server Activity A-1 Describing network models Star topology Nodes connected to central network connectivity device Central device distributes information packets Single break doesn’t affect other nodes If central device fails, all communication fails Bus topology Continuous line is formed Nodes connected to next in line Coaxial and T-connectors End of line uses terminating device Terminator absorbs the data signal Information passes through each node once Node determines if data is addressed to it Simple and inexpensive design Single break in line stops all communication Ring topology Each node is connected to two nodes on either side of it All nodes form a continuous loop Data token passes around the ring Node can transmit data if it has the token Mesh topology All nodes have independent connections to all other nodes Very fault-tolerant and scalable design Nodes need multiple network cards Complex wiring scheme Most often wide-area or campus links Might not be fully meshed Hybrid topology Two or more types of network topologies combined into one network Point-to-point vs. point-to-multipoint Point-to-point: – Dedicated connection between two nodes – Only those two nodes communicate over the connection Point-to-multipoint: – Multiple connections from single node to multiple nodes MPLS Multiprotocol Label Switching Uses labels to move data Protocol-agnostic network Operates between OSI Layers 2 and 3 Can carry different types of traffic for both circuit- and packet-switching clients Provides traffic management and QoS support Simple traffic shaping and Layer 3 VPNs Label Edge Routers Assign each data packet an MPLS header Header contains one or more labels called a stack Label stack is a 32-bit field Label contains four elements: – – – – 20-bit label value 3-bit traffic class field 1-bit bottom-of-stack flag 8-bit time-to-live (TTL) field Activity A-2 Describing physical network topologies Topic B Topic A: Network topologies Topic B: LAN technologies Topic C: WAN technologies Topic D: Virtual networks Ethernet 10 Gigabit Ethernet (10GbE) – Fastest Ethernet standard – Data rate of 10 gigabits per second 1000-Mbps Ethernet (Gigabit Ethernet) – Data rate of 1000 Mbps (1 gigabit per second) – Used for large, high-speed LANs and heavy-traffic server connections 100-Mbps Ethernet (Fast Ethernet) – Data rate of 100 Mbps 10-Mbps Ethernet (Twisted-pair Ethernet) – Data rate of 10 Mbps – Became known as Ethernet IEEE 802.3 – All subsequent Ethernet architectures conform to IEEE 802.3 Ethernet media BASE-R — Fiber optic cable BASE-W — Wide Area Network Physical Layer (WAN PHY) – Fiber optic cables – Same types of fiber and support the same distances as 10GBASE-R – Ethernet frames encapsulated in SONET frames BASE-T — STP or UTP BASE-C — Shielded copper twisted-pair continued Ethernet media, continued F typically identifies fiber optic cabling R refers to LAN technologies W refers to WAN encodings S, L, and E designate wavelength 10-Gigabit Ethernet standards Standard Medium Distance 10GBASE-T Copper twistedpair, shielded or unshielded 100 meters with CAT6a; up to 55 meters with CAT6 10GBASE-SR, 10GBASE-SW Multi-mode fiber 26 or 82 meters, depending on cable type Notes Preferred choice for optical cabling within buildings. 300 meters over 50 microns at 2000 MHz per km with OM3 multi-mode fiber 10GBASE-LR, 10GBASE-LW Single-mode fiber 10 km 10GBASE-ER, 10GBASE-EW Single-mode fiber 40 km Used to connect transceivers. Gigabit Ethernet standards Standard Medium Distance Notes 1000BASE-T Unshielded twistedpair: CAT5, CAT5e, or CAT6 100 meters per network segment Requires all four wire pairs. 1000BASE-CX Balanced copper 25 meters shielded twisted-pair An initial standard for Gigabit Ethernet connections. 1000BASE-LX Single-mode optic fiber 5 km* (See the notes below this table in course book.) 1000BASE-LX10 Single-mode optic fiber 10 km Wavelength of 1270 to 1355 nm. 1000BASE-BX10 Single-mode fiber, over single-strand fiber 10 km Different wavelength going in each direction— 1490 nm downstream, 1310 nm upstream. 1000BASE-SX Multi-mode optic fiber 500 meters Fast Ethernet standards Standard Medium Distance Notes 100BASE-TX Twisted-pair copper, CAT5 or above 100 meters per network segment Runs over two pairs: one pair of twisted wires in each direction. The most common Fast Ethernet. 100BASE-FX Single- or multi-mode fiber 400 meters for halfduplex 2 km for full-duplex over MMF Uses two strands: one for receiving and one for transmitting. Not compatible with 10BASE-FL. 10BASE-T 10 Mbps Copper twisted-pair cable Up to 100 meters Easier to install than coax Ethernet Ethernet bonding Combines bandwidth of two NICs Increases bandwidth Provides fault tolerance Data transmission Ethernet LANs are broadcast domains Wire is a shared transmission system All nodes detect the data transmission on the network Only the node to which the data was addressed receives it Data collisions Channel access methods Determine physical methodology by which data is sent across transmitting media CSMA/CD – Carrier sensing – Multiple access – Collision detection CSMA/CA – Avoids collisions; does not detect them – Uses alert messages Activity B-1 Describing Ethernet standards Topic C Topic A: Network topologies Topic B: LAN technologies Topic C: WAN technologies Topic D: Virtual networks Wide area networks Span larger geographical distances Connect multiple LANs using high-speed communication lines Expand beyond own premises Typically lease data lines from public carrier Packet vs. circuit switching Packet switching: – Data grouped into packets before being sent over shared network – Packets can contain a variety of data types – Packets can be buffered and queued – Can result in transmission delays – Examples: LAN and Internet Circuit switching: – Dedicated path for data transmission between two nodes – Transfer moves at non-stop rate – Path unavailable for other traffic until it’s released – Examples: PSTN and ISDN WAN connections WAN connection Description Dial-up networking (DUN) Uses a modem to connect through regular analog phone lines. Digital Subscriber Line (DSL) High-speed connections made over regular analog phone lines. Cable Connections made over the same lines that carry cable television signals. Satellite Connections made by sending signals to and receiving signals from satellites in orbit around the earth. Wireless Connections made through infrared light or radio waves. Wireless connections can also be made over cellular telephone networks or via satellite. Cellular Connections made through a cell phone or laptop’s cellular network PC Card on a cellular phone network. continued WAN connections, continued Used to connect: – Small ISP or large business to regional ISP – Regional ISP to an Internet backbone T lines and E lines X.25 and frame relay ATM POTS/PSTN Dial-up system over telephone lines Connection isn’t continuous Phone and data share line; only one can be used at a time Max data speed 56 Kbps Modem bonding combines speed of multiple modems ISDN Uses phone lines – 2 data channels – Control signal channel Data not converted to analog Terminal adapter Each data channel can transmit data at up to 64 Kbps Two channels can be combined to move data at speed of 128 Kbps Basic Rate Interface (BRI) PRI: 23 channels + control channel DSL High-speed data and voice transmission line Uses telephone wires for data transmission Carries digital data at frequencies above voice transmission Can transmit voice and digital data on same line at same time Typical speeds: 1.5 Mbps in both directions continued DSL, continued ADSL — Up to 640 Kbps upstream and 7.1 Mbps downstream SDSL — Up to 1.544 Mbps HDSL — Up to 1.5 Mbps VDSL — Up to 52 Mbps downstream and 16 Mbps upstream DSL Lite or G.Lite — Up to 384 Kbps upstream and 6 Mbps downstream Can bond multiple DSL lines for higher bandwidth Cable Uses transceiver (cable modem) to send and receive data Uses same line as cable TV Different frequencies Speed examples: 500 Kbps up to 10 Mbps Optional VoIP Satellite Useful in rural areas Uses dish mounted on building to communicate with stationary satellite in orbit Downlink uses satellite (up to 1.5 Mbps) Uplink sometimes dial-up Wireless Technologies that don’t use cables Public radio, cell phones, one-way paging, satellite, infrared, and private, proprietary radio More expensive to install and use Health concerns; wireless network can interfere with other devices Two types: fixed-point wireless and mobile wireless WiMAX 802.16 Air Interface Standard Worldwide Interoperability of Microwave Access Provides DSL and T1-level service Point-to-multipoint broadband wireless access standard Used for WANs and MANs 10–66 GHz licensed; 2–11 GHz unlicensed 70 Mbps Max of 31 miles Doesn’t require a line of sight Cellular Provided by major cell phone companies Access via cell signal with Internet-capable phone or laptop using cellular network PC card Faster than dial-up; slower than DSL or cable T and E lines First digitized voice transmission Work with leased digital communications line Transmit both voice and data T1 – 24 channels – 64 Kbps each – Total of 1.544 Mbps T3 – 672 channels – Total of 44.736 Mbps continued T and E lines, continued E carrier: European equivalent of T line – E1: 2.048 Mbps – E3: 34.368 Mbps T and E use 4 wires: 2 for receiving and 2 for sending Fiber optic and STP preferred over coaxial Repeaters every 6000 ft. continued T and E lines, continued Business lines – T1: coaxial, microwave, or fiber optic – T3: microwave or fiber optic Can lease fractional line – T1: 64 Kbps increments – T3: 1.544 Mbps increments D3 (Digital Signal 3): Digital T3 or E3 line X.25 and frame relay Packet-switching communication protocols Designed for long-distance data transmission Packet-switching technology – – – – Divides data into packets Sends each packet separately Used on Internet Uses bandwidth efficiently continued X.25 and frame relay, continued Frame relay – Digital – T1 or T3 lines – Speeds from 64 Kbps to 44.736 Mbps X.25 – Analog – Up to 56 Kbps Both use a permanent virtual circuit (PVC) continued X.25 and frame relay, continued PVCs aren’t dedicated lines – You specify Nodes (two endpoints) Amount of bandwidth required – Carrier sends data along any number of paths between the two endpoints Advantage: pay for only the amount of bandwidth you need International businesses use frame relay ATM Very fast network technology Used with LANs and WANs Uses cells to transmit data, voice, video, and frame relay traffic Each cell is 53 bytes – 48 bytes of data – 5-byte header Uses virtual circuits – PVCs – SVCs Throughput of 622 Mbps Best with fiber optic cable; can use TP SONET and SDH Synchronous Optical Network ANSI standard for signal transmission on optical networks Signal Digital Hierarchy: European counterpart to SONET Categories: Signal Rate STS-1, OC-1 51.8 Mbps STS-3, OC-3 155.5 Mbps STS-12, OC-12 622.0 Mbps STS-48, OC-48 2.48 Gbps STS-192, OC-192 9.95 Gbps STS-768, OC-768 39.81 Gbps DWDM Dense wavelength division multiplexing Increases data capacity of fiber networks such as SONET and SDM Assigns optical signals to specific frequencies of light within a band Can carry multiple protocols without a common signal format PON Passive optical network Shared point-to-multipoint fiber network continued PON, continued Activity C-1 Discussing WAN bandwidth technologies Topic D Topic A: Network topologies Topic B: LAN technologies Topic C: WAN technologies Topic D: Virtual networks Virtual computers Virtual applications Virtual desktops Virtual servers Virtual PBX Virtualization concerns and risks Compliance with security standards Rogue VMs Orphaned VMs Legal and regulatory compliance Activity D-1 Exploring the benefits and risks of virtualization Cloud computing Key features – – – – – – Elastic provisioning Cost benefits Standardized API Simplified installation Multi-tenancy Reliability and redundancy Cloud deployment Public cloud Private cloud Mixed cloud Cloud categories Software as a Service Platform as a Service Infrastructure as a Service Risks and concerns Data residing outside your network Privacy and data loss Compliance with laws and regulations Intellectual property agreements Activity D-2 Exploring the benefits and risks of cloud computing Unit summary Described different logical and physical network topologies Compared and contrasted different LAN technologies Categorized WAN technology types and properties Identified virtual network components