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LAN - Local Area Network. A network that interconnects PCs, terminals, workstations, servers, printers, and other peripherals at high speed over short distances (ethernet, token ring, FDDI, ATM, wireless)
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WAN - Wide Area Network. A network that covers long-haul areas and usually utilizes public phone companies (T1/T3, ISDN, xDSL, Frame Relay, SMDS, ATM)
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The International Standards Organization (ISO) has developed OSI standard in order to provide some level of uniformity among network vendors. OSI reference model consists of 7 layers. Each layer provides a service for the layer immediately above it:
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(1) Physical: passes bit stream between computer and network; defines voltage used, the data transmission timing, handshaking requirements; EIA-RS232, RS449, ethernet, token ring, FDDI
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(2) Data Link: provides reliable data transfer between computer and network; packages data into data frames; HDSL, SDSL, ATM, FR, NDIS, ODI
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(3) Network: sets up and maintains connections; establishes virtual circuits between computers; IP, X.25, IPX
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(4) Transport: provides control of quality of service; TCP, UDP, SPX, NetBEUI
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(5) Session: handles coordination between processes; concentrates on network management, password recognition, logon and logoff procedures, network monitoring; SNMP, FTP, SMTP, Telnet
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(6) Presentation: provides data formatting and code conversion, network security and file transfers; AFP
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(7) Application: provides user interface to lower level; X.400, X.500, FTAM
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Thin ethernet cable
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50-ohm, 0.2-inch-diameter RG-58 A/U or RG-58 C/U
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Connector: BNC, BNC barrel, T-BNC, BNC terminator
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Max length of ethernet segment: 185 m
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Distance between nodes: 0.5 m
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Thick ethernet cable (yellow cable)
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50-ohm, 0.4-inch-diameterm, stiffer than thin cable
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Connector: N-series male connector, N-series barrel
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connector, N-series terminator
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Max length of ethernet segment: 500m
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Distance between nodes: 2.5 m
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Broadband coax cable
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75-ohm; can carry integrated voice, data and video signals
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bridge - a network device that connects two (or more) LANs and forwards or filters data packets between them, based on their destination address; bridge operates at the Data Link Layer (OSI) and is transparent to higher network protocols
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switch - multi-port device designed to increase performance; packet are filtered or forwarded based on their MAC source and destination addresses. There are Cut-Through switches and Store-and-Forward switches
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router - a network device capable of filtering/forwarding packets, reading their network addresses (e.g. IP) and route accordingly; router operates at the Network Layer (OSI)
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brouter - a device that routes specific protocols, such as TCP/IP and bridges other protocols
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gateway - a device for interconnecting 2 or more dissimilar networks; it can translate protocols and operates at all layers of OSI Reference Model
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Wireless (802.11) 2-10 Mbps
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Ethernet (802.3) 10 Mbps
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Iso Enet (802.9) 16 Mbps
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Token Bus/Ring (802.4,802.5) 4, 16 Mbps
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100VG-AnyLAN (802.12) 96 Mbps
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Fast Ethernet (802.3u) 100 Mbps
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FDDI (X3T9.5) 100 Mbps
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Fiber Channel 133, 266, 531, 1062 Mbps
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Giga Ethernet (802.3z) 1000 Mbps
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ATM 25, 100, 140, 155, 622 Mbps
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HiPPI 800, 1600, 6400 Mbps
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Modem 9.6, 14.4, 19.2, 28.8, 33.6, 56 Kbps
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Switched 56 KBPS 56 Kbps
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ISDN B, BRI(2B+D), PRI(23B+D) 64 Kbps, 144 Kbps, 1.544 Mbps
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T1 (DS-1) 1.544 Mbps
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X.25 up to (64 Kbps) 2 Mbps
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Frame Relay 56 Kbps-(1.544 Mbps)-36 Mbps
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HDSL 1.544 Mbps
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SDSL 160 Kbps- 2 Mbps
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ADSL 1.5 - 8 Mbps
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VDSL 2.3 - 51.84 Mbps
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SMDS 56Kbps - 34 Mbps
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T3 (DS-3) 45.736 Mbps
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SONET OC-1/STS-1 51.84 Mbps
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ATM-25 25 Mbps
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ATM DS-3 44.736 Mbps
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ATM TAXI 100 Mbps
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ATM OC-3,12,48,128 155.52, 622.08 Mbps, 2.488, 6.4 Gbps
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standard: IEEE 802.3
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media: optical fiber, coax, twisted pair, microwave
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media access: CSMA/CD (Carrier Sense Multiple Access/Collision Detection)
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bandwidth: 10 Mbps, full duplex-20Mbps
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topology: bus, star
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max frame size: 1500 Bytes
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max nodes: 1024
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max interstation distance: fiber - 2km; twisted pair - 70 m; coax - 1.5 km; microwave - 4.5 miles
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max coverage: 2.8km
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connection between hubs: crossover cable
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frame formats: Ethernet_II, Ethernet_802.3, Ethernet_802.2
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specification: IEEE 802.3u; speed: 100 Mbps; access method: CSMA/CD;
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topology: star; applications: enterprise servers, backbone
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100base-TX
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wiring : cat5 UTP/STP; length : 100m; connector : 8-pin (RJ45), 9-pin (D-type)
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two pair of wire: one for receive and one for transmit
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100base-FX
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wiring 62.5/125 Mm fiber; length 2 km
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connector SC, ST, MIC
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100base-T4
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wiring Cat 3 or above; four pair wire cat 3; length 100 m
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connector 8-pin (RJ45)
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100VGAnyLAN
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a new ethernet standard IEEE 802.12; access method: demand priority
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speed: 96 Mbps; wiring: UTP cat3,5; fiber single mode, multimode
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standard: IEEE 802.5
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media: optical fiber, twisted pair STP or UTP
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media access: Token Passing - information is traveling from station to station and is regenerated by each station
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bandwidth: 4 or 16 Mbps
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max frame size: (4 Mbps) no limit; (16 Mbps) 18,000 Bytes
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max nodes: 260 for STP and 72 for UTP
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max interstation distance: 300 m to MSAU
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topology: physical star, logical ring
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hardware:
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Token Ring Adapter - 4 MBPS and 16 MBPS
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MSAU - Multi-Station Access Unit, usually 16 ports
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Token Ring Adapter Cables and patch cables - 9 pin connector on one end and "Type A" connector that plugs into the MSAU
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100VG AnyLAN is a 100 Mbps high speed networking standard that was originally developed to transmit Ethernet or Token Ring packets over existing wiring (UTP cat 3,4,5 or fiber);
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VG stands for Voice Grade
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standard: IEEE 802.11
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actual throughput: up to 96 Mbps
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frames: standard 802.3 ethernet format or 802.5 TokenRing format
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distance (hub to node, or hub to hub): UTP cat3 - 100m; UTP cat5 - 200m; fiber - 2000m
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access method: Demand Priority (MAC layer protocol), no collisions
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compatible with existing software; easy to implement
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number of nodes: up to 1024 unbridged nodes
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ideal for multimedia applications (traffic can be prioritized)
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comparison between CSMA/CD and Demand Priority:
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CSMA/CD: try to send whenever there is data
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Demand Priority: only send when it is O.K. to do so; a station demands of the hub the permission to send and indicates the priority; hub services higher priority first.
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topology: cascade to 3 levels of hubs (total network span=1200m)
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hardware: NICs PCI-VG10/100, EISA-VG10/100 , ISA-VG10/100 with 2 RJ45 (one for ethernet, one for VG); VG-HUB with RJ45 VG ports, HUB with ethernet-to-100VG Bridge
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vendor: Ragula Systems, Cisco, Cabletron, Hewlett Packard, etc
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FDDI is an excellent medium for building backbones of LANS.
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standard: ANSI X3T9.5; media: optical fiber
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media access: Timed Token Passing Dual Ring
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bandwidth: 100 Mbps (FDDI network actually has a 125 Mbps signaling rate, however 4B/5B (Differential Manchester) encoding takes up to 25 Mbps)
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max frame size: 4500 Bytes; max nodes: 500
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max interstation distance: 2 km; max distance: 100 km (60 miles)
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topology: dual ring (for redundancy); stations act as repeaters; DAS - Dual Attached Station is attached to both rings; SAS - Single Attached Station is attached only to the primary ring
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connectors: ST, MIC, SMA906; status: mature, reliable and proven
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transition modes: asynchronous - traffic is not prioritized; synchronous - allows for prioritization of time-sensitive traffic; circuit-based (in FDDI II only) -allows for dedicated communication line with guaranteed bandwidth
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standard: IEEE 802.11
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types of implementation:
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DSSS -- Direct Sequence Spread Spectrum (higher performance)
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FHSS -- Frequency Hopping Spread Spectrum (lower cost)
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OSI Physical layer (Access Point, antennas, LAN interfaces)
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radio-frequency-based -- FCC license not required for the following frequencies 902-928 MHz, 2.4-2.4835 GHz, 5.725-5.850 GHz
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infrared-based -- no government regulations
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OSI Data Link layer:
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DFWMAC - Distributed Foundation Wireless Media Access Control
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access method: CSMA/CA - Carrier Sense Multiple Access with Collision Avoidance (no ability to detect collisions)
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typical parameters:
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data rates: 2 Mbps, 10 Mbps
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distance: up to 3 miles; up to 10 miles with amplifiers;
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up to 30 miles - point-to-point without obstacles (mountains, hills)
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topologies: point-to-point, point-to-mulitipoint
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Characteristics:
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fixed size packets (cells) - 53 bytes
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switching technology
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high, scalable bandwidth
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ability to dedicate a certain bandwidth to an application (QoS - Quality of Service)
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can handle real-time applications
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broadband technology (for voice, video, and data)
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viable for LANs and WANs
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still the most expensive service
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ATM network consists of ATM switches
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wireless ATM (28 GHz range), SMDS over ATM, Frame Relay over ATM
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SONET / SDH - Synchronous Optical Network / Synchronous Digital Hierarchy
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physical layer standard for fiber optic transmissions standardized by ANSI and recommended by CCITT
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SONET is the carrier format used in the USA in which OC3c corresponds to a 155 Mbps
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SDH is a European carrier system in which STM-1 corresponds to 155 Mbps
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ATM and SMDS operates on top of SONET
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interface rates: OC1, OC3, OC9, OC12, OC18, OC24, OC36, OC48
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OC-3c/STM-1 SONET/SDH
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OC-12c/STM-4c SONET/SDH
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fiber based or microwave based (OC3, 6 GHz)
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framing STS-3c/STM
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Classical IP-Over-ATM (IPOA RFC 1577)
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ATM is a connection-oriented protocol, which means that connection must be established between two communicating entities before data transfer can begin. IP is inherently connectionless. There are 2 ways to run transparently IP traffic over ATM: Classical IP and LAN emulation
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The term "classical" indicates that the ATM network has the same properties as existing legacy LANs.
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SVC management is performed via UNI specification, which defines signaling: Q.93B (UNI3.0), Q.2931 (UNI3.1).
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Once a Classical IP connection has been established, IP datagrams are encapsulated using IEEE 802.2 LLC/SNAP and are segmented into ATM cells using AAL5.
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There is no support for broadcast and multicast in a Classical IP environment. The Classical network is divided into LISs (Logical IP Subnets).
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Each LIS must have only on ATM ARP server configured on a switch or a host ARP server is responsible for resolving an IP addresses into ATM addresses.
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LAN Emulation: IP-Over-ATM (IPOA LANE 1.0)
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LANE over ATM is the natural path for migrating ethernet and token ring LANs to fault tolerant ATM network. LANE ver1.0 emulates MAC layer ; standard 1996
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Applications can run unmodified over an ATM network. LANE works by allowing the OS and all protocols at and above Layer 2 to seamlessly operate with ATM
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components: LES, LEC, LECS, BUS
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version 1.0 permits only one LES / BUS on an emulated network creating single point of failure
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LECS - LAN Emulation Configuration Server contains the configuration of the emulated networks
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LES - LAN Emulation Server mapping between MAC addresses and ATM addresses
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BUS - Broadcast and Unknown Server handles broadcast and multicast as well as unknown addresses
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LEC - LAN Emulation Client runs on every workstation
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Emulated LAN operates in client/server environment applying Virtual LAN concept
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Voice over ATM (VTOA - Voice and Telephone over ATM)
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QoS parameters: delay, jitter in delay, loss rate
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CBR for voice current ATM Forum specification
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silence detection (voice has 60% of silence)
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unstructured circuit emulation: maps entire T1 circuit to a single ATM VC
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structured circuit emulation: maps individual 64 Kbps circuits to ATM VCs
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Compression: G.726 ADPCM, G.728 LD-CELP, G.729 CS-ACELP
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average national network delay for voice traffic specified by G.114, G.131, G.126
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current VTOA: lack of compression, lack of silence suppression, limitations of AAL1
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Other ATM Protocols
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MPOA - Multi Protocol Over ATM : layer 3 protocols like IP or IPX can be carried transparently over an ATM network
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mapping on network layer on ATM network
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performance, scalability
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sends routed traffic over connection-oriented circuits
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NHRP - Next Hop Reservation Protocol is used for forwarding
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CIF - Cells in Frames; solution for delivering ATM to the desktop
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IISP - Interim Inter-switch Signaling Protocol
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PNNI - Private Network to Network Interface
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I-PNNI- Integrated PNNI
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Hardware: ATM switch, ATM analyzer, ATM adapter
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ATM Carrier Services: MCI, WorldCom, Sprint, AT&T, GTE, Pacific Bell, US West, Ameritech, Southwestern Bell, Bell Atlantic
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The services are provided by hundreds POPs (Point of Presence)
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Frame: a group of all 24 T1 sub-channels with 8 bits per channel and one framing bit. One frame equals 193 bits; 12 frames = D4; 24 frames = ESF
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Channelized T1 - used to supply 24 individual channels to different locations
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E1 - 32 DS0 channels = 2,048 Kbps (in Europe) AMI is not used; B8ZS is replaced by HDB3 encoding (High Density Bipolar)
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Devices required:
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CSU / DSU = Channel Service Unit / Digital Service Unit
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V.35, EIA RS449 or RS 530 interface to DTE; RJ48C or RJ48X jack
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LAN---bridge --(V.35)---CSU/DSU---(T1)---CSU/DSU--(V.35)---bridge--LAN
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Bell Atlantic: installation $622; usage $642/month (in 1997)
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ISDN integrates data, voice, and video signals into a digital telephone line
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Specification:
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CCITT in 1984 (spec I.100-400), 1988 (I.500-600) ; 96 basic specifications
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Physical I.430/431 basic/primary interface
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Logical Link I.441/Q.921 Link Access Protocol D channel (LAPD)
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Network I.451/Q.931 control signaling, call control
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Narrow-band ISDN (N-ISDN)- original standard operates over copper cable (operates on physical,logical and network layers)
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BRI = Basic Rate Interface (2B+D=144 Kbps)
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B = 64 Kbps, B (bearer) - data transmission channel
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D = 16 Kbps, D (delta) - Signaling (2 modes: 64 Kbps and 56Kbps)
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PRI = Primary Rate Interface (23B+D=1.544 Mbps) in Europe 30B+D (D = 64 Kbps, signaling channel)
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Hardware:
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Popular switches : 5ESS AT&T, DMS100
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NT1 (Network Termination) converts the 2-wire (U) ISDN line into 4-wire (2 pairs) connection for the terminal adapter (S/T)
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Terminal Adapter: minimalist approach (only ISDN): ISDN*tek Internet+Plus; Analog and ISDN in one device (ISDN and fax, analog phone or modem): Digi DataFire Go!; High End TAs : Motorola BitSURFER Pro
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Services: ISDN (digital) phone, ISDN fax, PC with ISDN, videoconferencing
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Security: PAP - Password Authentication Protocol, CHAP - Challenge Handshake Authentication Protocol
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SPID: Service Provider ID (example:31547792030000/31547788030000)
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Service cost - installation: $160; usage: $36/per line per month; TA ~$500
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xDSL - allows mixing data, voice and video over conventional, copper phone lines.
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The service under development (since 1987).
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Competes with ISDN and cable modems
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xDSL family : ADSL, RADSL, IDSL, HDSL, SDSL, VDSL
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All xDSL technologies run on existing copper phone lines and use modulation to boost transmission rates.
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CAP - amplitude phase modulation
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DMT - discrete multi-tone modulation
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DWMT- discrete wavelet multi-tone modulation.
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The key in xDSL technology is modulation, a process in which one signal modifies a properties of another.
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Hardware: DSL requires modems and splitters for end-users; carriers use DSLAMs (digital subscriber line access multiplexers)
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Differences between xDSL technologies: speed, operating distance, applications, ratio between up and downstream
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Different approaches: ATM-based ADSL, ISDN DSL. The important thing is what is running over xDSL...
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Developed to address the slowness of X.25 network. FR specification removes flow control and error checking from the intermediate nodes.
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FR evolved from X.25 and ISDN. It operates on the first and second layer of OSI Reference Model. The standard proposed in 1984.
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Characteristics:
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line speed: 56Kbps - 1.544 Mbps ---> 36 Mbps ---ᡥ Mbps
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packet (variable size) oriented, switched communication method,
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connection-oriented technology based on the leased point-to-point circuits (PVC - Permanent Virtual Channel)
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not intended for time-sensitive applications due to its variable-length frames
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Hardware:
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FRED - Frame Relay Assembler / Disassembler
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FRND - Frame Relay Network Device (Node)
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Frame Relay Forum supported by Cisco, DEC, Northern Telecom, StrataCom
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Public network offering available from most public Carriers: AT&T, MCI, Sprint, RBOCs (RBOC=Regional Bell Operating Company)
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Frame Relay vs. ATM
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both offer QoS
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both connection-oriented technologies
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FR top bandwidth - 45 Mbps
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ATM lowest bandwidth -25 Mbps
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FR: variable size packets; ATM : fixed length cells;
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FR addresses E.164 and X.121 specifications
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ATM addresses E.164, ICD, DCC
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FRF.5 spec (network internetworking)
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FRF.8 spec (service internetworking)
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TCP/IP protocol suite (selected list):
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Telnet - Remote login (RFC 854, 855)
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FTP - File Transfer Protocol (RFC 959)
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SMTP - Simple Mail Transfer Protocol (RFC 821, 822)
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NFS - Network File System (RFC 1001,1002)
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DNS - Domain Name Service (RFC 1035)
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NIS - Network Information System (Yellow Pages)
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X - Remote Windowing System
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RPC - Remote Procedure Call
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SNMP - Simple Network Management Protocol
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TCP - Transmission Control Protocol (RFC 793)
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UDP - User Datagram Protocol (RFC 768)
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ICMP - Internet Control Message Protocol (RFC 792)
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IGMP - Internet Group Management Protocol
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IP - Internet Protocol (RFC 791)
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ARP, RARP - (Reverse) Address Resolution Protocol (RFC 826)
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IP routing
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RIP - Routing Information Protocol (RFC 1058)
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OSPF - Open Shortest Path First (RFC 1247)
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EGP - Exterior Gateway protocol (RFC 904)
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Transport layer: TCP/UDP
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port numbers are used to identify applications; on Unix port numbers are defined in /etc/services; well-known ports:
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21 (ftp), 23 (telnet), 25 (smtp), 80 (www), 119 (nntp), 123 (ntp)
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sockets - a combination of IP address and port number
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Other Protocols
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DHCP - Dynamic Host Configuration Protocol designed (Microsoft) to centrally manage IP addresses on the network by allocating them dynamically whenever a client requires one. DHCP maintains a database of the addresses reserved and leased to clients.
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BOOTP- Booting Protocol (RFC 951)
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SNMP - Simple Network Management Protocol SNMP v1,2,3
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What is IPv6 ?
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IPv6 stands for Internet Protocol versions 6. The current version is called IPv4. The explosive growth of the Internet is the primary reason a new version of IP is being developed. IPv6 has:
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ability to better handle video and audio transmission
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enhanced addressing scheme
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support for data integrity, authentication, confidentiality
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IPv6 isn't backward-compatible with IPv4. A technique called tunneling lets the two protocols coexist. IPv6 packets are tunneled by encapsulating the packets in IPv4 datagrams and routing them over the IPv4 network.
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IPv6 (IPng = next generation) completely redefines the nature of Internet addresses; IPv6 is 128 bit long. It is large enough to assign unique IP address for every proton in the earth, or install several billion computers on every square meter of the Earth's surface.
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Fore more information see:
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http://playgroud.sun.com/pub/ipng/html/ipng-main.html
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IP Unicast, Multicast and Broadcast
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A IP broadcast goes to every device on the network, often distributing control data that supports the network.
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In IP multicasting, the data goes only to devices that request it.
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Unicast datagram has defined and unique sender and recipient.
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IP multicasting is a way of forwarding data to a group of host systems simultaneously. It is similar to IP broadcasting except that instead of all hosts receiving the data, only systems which belong to a multicast host group receive the data.
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A multicast host group is a group of systems which have the same Class D
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IP destination address (for example 224.99.0.6);
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Class D covers addresses: 224.0.0.0 - 239.255.255.255
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Multicast must be enabled on hosts and routers
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If multicast is not supported, we have to built a tunnel i.e. encapsulate multicast messages in unicast datagrams
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IGMP (RFC 1112) - Internet Group Management Protocol - propagates multicast membership group information; this is used by multicast hosts to report their group membership to any immediately neighboring multicast routers; IGMP implements prunning algorithm in order to minimize traffic (paths to networks on which there are no subscribed recipients are pruned);
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TTL - Time-to-Live limits the geographic range of a multicast session; ttl value is assigned to each packet for the session; ttl threshold is set in IP multicast-capable routers; ttl field in each packet is decremented as it hops from router to router; before the multicast packet hops over any mrouter its ttl value has to be greater than the mrouter's threshold value
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PIM - Protocol Independent Multicast (routing protocol from Cisco, Bay Networks). PIM is used by multicast routers to determine which other multicast routers should receive multicast packets; dense-mode: transmits packets to all LANs unless it receives instruction to the contrary; sparse-mode: transmits packets to LANs which have made "join" request
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DVMPR - Distance Vector Multicast Routing Protocol (Cisco, Bay, 3Com) more complicated than RIP
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MOSPF - Multicast Open Shortest Path First (3Com) - multicast routing
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Transport Layer:
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RTMP - Routing Table Maintenance Protocol, maintains and broadcasts routing information (every few seconds)
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AEP - AppleTalk Echo Protocol, sends datagrams to other nodes in the network to determine their existence
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ATP - AppleTalk Transaction Protocol, determines whether requests are lost or delayed
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NBP - Name Binding Protocol, translates device a name into AppleTalk address
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Session Layer:
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ADSP - AppleTalk Data Stream Protocol, works with ATP to ensure reliable data transmission; includes flow control
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ZIP - Zone Information Protocol, maps network numbers to network zones; the information is kept in ZIT=Zone Information Table
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ASP - AppleTalk Session Protocol, responsible for opening and closing sessions
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PAP - Printer Access Protocol, maintains print service
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Presentation and Application Layers:
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AFP - AppleTalk Filing Protocol
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PostScript - paged description language
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AppleShare is a centralized file-sharing system that runs on top of AppleTalk on a Macintosh system; AppleShare servers are accessed by AppleShare clients
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NetBIOS - Network Basic Input Output System
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NetBEUI - NetBIOS Extended User Interface
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Protocols designed by IBM and Microsoft to support network communication in a small-sized LAN consisted of personal computers (Microsoft Network)
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Implementation: OS/2, Windows for Workgroups, Windows NT, Microsoft LAN Manager, IBM LAN Server
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In Windows NT network one can choose the protocol used for networking: NetBEUI, TCP/IP or IPX
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NetBIOS is a generalized program-to-program communication facility that enables peer-to-peer and client/server communication between PCs operating in a LAN environment.
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NetBIOS supports 3 services:
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name service (no centralized name servers are required)
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session service (connection-oriented)
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datagram service (connection-less; used to deliver broadcast)
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NetBIOS names can be resolved to TCP/IP addresses in 2 ways:
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LMHOSTS file
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WINS - Windows Internet Name Service
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originally created by Sun Microsystems, Inc as a file sharing system for TCP/IP networks.
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Sun's concept : The network is the computer = The computer is the network
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NFS is a distributed, client-server file system: the client requests the information and the NFS server distribute the information
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it is widely implemented, contains security features
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NFS allows users to access files and printers on other systems as if they were local files
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server: broadcasts (exports) the directories that it is sharing
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client: mounts (automounts) the directories
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specifications:
-
NFSv2 RFC 1094
-
NFSv3 RFC 1813
|
|
supports IP, DECnet, IPX, AppleTalk, Mac layer bridging;
|
|
operates over dialup or leased lines;
|
|
allows to assign IP address automatically (dynamically);
|
|
there are no speed limitations built into the PPP protocol;
|
|
frames have variable sizes;
|
Physical Layer:
-
EIA-232E, EIA-422, EIA-423, V.24, V.35
|
Data Link Layer:
-
HDLC- High-level Data Link Control
-
LCP - Link Control Protocol
|
Network Layer:
-
NCP - Network Control Protocol
|
Outside Index
Summary of Material
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