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Standards and Network Protocols. Department of Computer and System Instituto Tecnológico de Morelia jcolivar@itmorelia.edu.mx 19.72388 lat, -101.1848 long. M.C. Juan Carlos Olivares Rojas. Disclaimer.
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Standards and Network Protocols Department of Computer and System Instituto Tecnológico de Morelia jcolivar@itmorelia.edu.mx 19.72388 lat, -101.1848 long M.C. Juan Carlos Olivares Rojas
Disclaimer Some material in this presentation has been obtained from various sources, each of which has intellectual property, so in this presentation will only have some rights reserved. These slides are free, so you can add, modify, and delete slides (including this one) and slide content to suit your needs. They obviously represent a lot of work on my part. In return for use, I only ask the following: if you use these slides (e.g., in a class) in substantially unaltered form, that you mention their source.
Outline Standards of IEEE LAN Conection. 802 Project Connection. 802.1 Connection between Networks. 802.2 Logical Link Control (LLC). 802.3 Ethernet. 802.4 Token Bus. 802.5 Token Ring. 802.6 FDDI. 802.11 Wireless LAN.
Outline Protocol Architectures TCP/IP NetBEUI/NetBIOS IPX/SPX. Emergent Protocols Similarities and differences between OSI and TCP/IP models.
Objectives of the Session • The students will know the basis of intenrnational computer networks standards. • The students will know and apply the LAN concepts.
Standards of IEEE LAN Conection The standards only indicate how computer networks must be works guarantee interoperability between another Equipments. The main functions in the 802.x standards are the framming and Medium Access Control.
IEEE 802.x Technologies • The group of standards 802.x is concern about the implementation and use of Local Area Network (e.g. TokenRing, Ethernet) and Wide Area Network (e.g. FDDI, WiMax). • These standars are focused in DataLink Layer. The transmission medium can be wired o wireless. • Some standards are focused in define services in DataLink Layer such quality of service, security, among others.
802.1 Connection between Networks • DataLink Services • Provide services to the Network Layer • Send and receive data in a frame format • Processing and error correction • DataFlow Control • Medium Access Control ***
Where is the link layer implemented? in each and every host link layer implemented in “adaptor” (aka network interface card NIC) Ethernet card, PCMCI card, 802.11 card implements link, physical layer attaches into host’s system buses combination of hardware, software, firmware application transport network link link physical host schematic cpu memory host bus (e.g., PCI) controller physical transmission network adapter card
MAC Addressing • MAC (or LAN or physical or Ethernet) address: • function:get frame from one interface to another physically-connected interface (same network) • 48 bit MAC address (for most LANs) • burned in NIC ROM, also sometimes software settable
LAN Addresses Each adapter on LAN has unique LAN address Broadcast address = FF-FF-FF-FF-FF-FF 1A-2F-BB-76-09-AD LAN (wired or wireless) = adapter 71-65-F7-2B-08-53 58-23-D7-FA-20-B0 0C-C4-11-6F-E3-98
802.2 Logical Link Control (LLC) The Logical Link Control (LLC) data communication protocol layer is the upper sublayer of the Data Link Layer specified in the seven-layer OSI model (layer 2). It provides multiplexing and flow control mechanisms that make it possible for several network protocols (IP, IPX) to coexist within a multipoint network and to be transported over the same network media.
802.2 Logical Link Control (LLC) The LLC sub-layer acts as an interface between the Media Access Control (MAC) sublayer and the network layer. It is the same for the various physical media (such as Ethernet, token ring, and WLAN).
Medium Access Control • There are a lot of technices for sharing the transmision medium. The more used in computer networks are: • ALOHA • CSMA • Protocols without colision • Wireless Protocol • Other Multiplexation
ALOHA The frames are transmitting in arbitrary moment
CSMA (Carrier Sense Multiple Access) 5: DataLink Layer CSMA: listen before transmit: If channel sensed idle: transmit entire frame • If channel sensed busy, defer transmission • human analogy: don’t interrupt others! • collisions can still occur: • propagation delay means • two nodes may not hear • each other’s transmission • role of distance & propagation delay in determining collision probability
CSMA/CD (Collision Detection) CSMA/CD: carrier sensing, deferral as in CSMA • collisions detected within short time • colliding transmissions aborted, reducing channel wastage • collision detection: • easy in wired LANs: measure signal strengths, compare transmitted, received signals • difficult in wireless LANs: received signal strength overwhelmed by local transmission strength
CSMA Collision Detection CSMA/CD can be in 3 states: contention, transmission, or idle
Token Passing • control token passed from one node to next sequentially. • token message • concerns: • token overhead • Latency • single point of failure (token) T (nothing to send) T data
Extra (10 points in a Final Unit) • Make a program wich simulate Ethernet Newtrok with collisions. • Must be graphical (easy way) with computers conects in a Hub or by Bus. • The paramaters (time, persistence, frecuency) cab be set up. • The simulation must show the colisions and calculate statistc
802.3 Ethernet “dominant” wired LAN technology: • cheap $20 for NIC • first widely used LAN technology • simpler, cheaper than token LANs and ATM • kept up with speed race: 10 Mbps – 10 Gbps Metcalfe’s Ethernet sketch
Ethernet: Unreliable, connectionless • connectionless: No handshaking between sending and receiving NICs • unreliable: receiving NIC doesn’t send acks or nacks to sending NIC • stream of datagrams passed to network layer can have gaps (missing datagrams) • gaps will be filled if app is using TCP • otherwise, app will see gaps • Ethernet’s MAC protocol: unslotted CSMA/CD
Manchester encoding • used in 10BaseT • each bit has a transition • allows clocks in sending and receiving nodes to synchronize to each other • no need for a centralized, global clock among nodes! • Hey, this is physical-layer stuff!
802.4 Token Bus • Token bus is a network implementing the token ring protocol over a "virtual ring" on a coaxial cable. • A token is passed around the network nodes and only the node possessing the token may transmit. • If a node doesn't have anything to send, the token is passed on to the next node on the virtual ring.
802.4 Token Bus • Each node must know the address of its neighbour in the ring, so a special protocol is needed to notify the other nodes of connections to, and disconnections from, the ring. • It is mainly used for industrial applications. Token bus was used by GM (General Motors) for their Manufacturing Automation Protocol (MAP) standardization effort.
802. 5 Token Ring • Token ring is a local area network protocol which resides at the data link layer (DLL) of the OSI model. It uses a special three-byte frame called a token that travels around the ring. Token ring frames travel completely around the loop. • Cabling is generally IBM "Type-1" shielded twisted pair, with unique hermaphroditic connectors.
Token Ring • Initially (in 1985) token ring ran at 4 Mbit/s, but in 1989 IBM introduced the first 16 Mbit/s token ring products and the 802.5 standard was extended to support this. • Token ring LANs normally use differential Manchester encoding of bits on the LAN media.
802.6 FDDI • Fiber distributed data interface (FDDI) provides a standard for data transmission in a local area network that can extend in range up to 200 kilometers. • These protocol is derived from the IEEE 802.4 token bus timed token protocol. • It uses optical fiber (though it can use copper cable, in which case one can refer to CDDI). FDDI uses a dual-attached, counter-rotating token ring topology.
FDDI • A FDDI network contains two token rings, one for possible backup in case the primary ring fails. The primary ring offers up to 100 Mbit/s capacity. When a network has no requirement for the secondary ring to do backup, it can also carry data, extending capacity to 200 Mbit/s. The single ring can extend the maximum distance; a dual ring can extend 100 km (62 miles).