Advantages of ATM :ATM Advantages ATM supports voice, video and data allowing multimedia and mixed services over a single network. High evolution potential, works with existing, legacy technologies Provides the best multiple service support Supports delay close to that of dedicated services Supports the broadest range of burstiness, delay tolerance and loss performance through the implementation of multiple QoS classes Provides the capability to support both connection-oriented and connectionless traffic using AALs Able to use all common physical transmission paths like SONET. Cable can be twisted-pair, coaxial or fiber-optic Ability to connect LAN to WAN Legacy LAN emulation Efficient bandwidth use by statistical multiplexing Scalability Higher aggregate bandwidth High speed Mbps and possibly Gbps
Flexible to efficiency’s expense, at present, for any one application it is usually possible to find a more optimized technology Cost, although it will decrease with time New customer premises hardware and software are required Competition from other technologies -100 Mbps FDDI, 100 Mbps Ethernet and fast Ethernet Presently the applications that can benefit from ATM such as multimedia are rare The wait, with all the promise of ATM’s capabilities many details are still in the standards process
High-speed communication Connection-oriented service, similar to traditional telephony Fast, hardware-based switching A single, universal, interoperable network transport A single network connection that can reliably mix voice, video, and data Flexible and efficient allocation of network bandwidth
The Address Resolution Protocol (ARP) is a telecommunication protocol used for resolution of network layer addresses into link layer addresses, a critical function in multiple-access networks. ARP is used for mapping a network address (e.g. an IPv4 address) to a physical address like an Ethernet address (also named a MAC address).ARP :picture the computers Matterhorn and Washington in an office, connected to each other on the office local area network by Ethernet cables and network switches, with no intervening gateways or routers.Example :
The Reverse Address Resolution Protocol (RARP) is an obsolete computer networking protocol used by a client computer to request its Internet Protocol (IPv4) address from a computer network, when all it has available is its link layer or hardware address, such as a MAC addressRARP :
It permits a host to determine its IP address from the network. This is useful for diskless hosts which need to configure themselves dynamically upon bootstrap. In this scenario, the diskless host reads the MAC address of its network adapter and sends out a RARP request for its IP address to the network. This is typically done with a broadcast request. As such, the RARP request is not forwarded by routers. One or more RARP servers would then reply to the diskless host with a unicast reply providing the IP address. Bootp provides another mechanism for doing this function. In addition, bootp allows more data than just the IP address to be sent.We need RARP/function does RARP serve :
It provides a mechanism to translate IP addresses into MAC addresses.we need ARP/ function ARP serve :
IP provides a connectionless or datagram service between and systems.There are a number of advantages of connectionless internetworking. i) A connectionless internet facility is flexible. It can deal with variety network, some of which are themselves connectionless. ii) A connectionless Internet service can be made highly robust. iii) A connectionless internet service is best for connectionless transport protocols, because it doesn't impose unnecessary overhead.
It allows host A to impersonate host B and respond to an arp request on behalf of host B. The original intention of this is to allow a router to respond to an arp request on one of its networks for a host on another of its networks. In this way, the router is able to make the different networks work in a more transparent way.Proxy ARP And Function does it serve :
1) It can be served high data rates typically 2Mbps. 2) Low error rates. 3) It is less expensive 4) It provides both parmanent & switched connection.
1) No mechanism for transmitting a damaged frame. 2) Difficult to configure. 3) no network layer. 4) Moe difficult to manage. 5) One serial port at the central site.
A protocol is a set of rules that governs data communications. A protocol defines what is communicated, how it is communicated and when it is communicated.Protocol :
a) Encapsulation b) Segmentation & resembling c) Connection Control d) Ordered delivery e) Flow Control f) Error control g) Addressing h) Multiplexing i) Transmission service.
References model : Protocol standard is also know as a reference model.References model :
It has two types ,These i) OSI & ii) TCP/IP OSI : The full form of OSI is the open System interconnection. OSI deals with connect opebn systems that is systems that are open communication with other system. It has seven phases/layer for communicating data from source to destination, this is why it is called seven layer model. 1) Application 2) Presentation 3) Session 4) Transport 5) Network 6) Data Link 7) Physical Fig : OSI Layer 1) Physical layer : The layer od OSI that co-ordinates the function required to transmit a bit over a physical medium called physical layer. It deals with the mechanical and electrical specification of devices. Characteristics : i) Physical characteristics of interfaces & media ii) It represents the data iii) Data rate iv) Synchronization of bits v) Physical topology vi) Transmission mode vii) Line configuration 2) Data Link layer : The layer of OSI that transforms the physical layer to a reliable link is called data link layer. Characteristics : i) It deals with framing ii) Physical addressing iii) Flow control iv) Error control v) Access control vi) Traffic regulation mechanism 3) Network Layer : The layer that responsible source to destination to delivery of packet multiple network is called network layer. Characteristics : i) Logical addressing ii) Routing iii) Connecting different network. 4) Transport Layer : The layer of OSI that is for process to process delivery of the entire message is called transport layer. Characteristics : i) Service point addressing ii) Segmentation and re-assembly iii) Connection control iv) Flow control v) Error control vi) Port control 5) Session Layer : The Layer of OSI that allows of different machine to establish session among them is called session layer. Characteristics : i) Provides enhanced service to the u ii) It allows the user to log into a remain time sharing system. iii) It means dialogue control among the devices iv) It allows traffic to go in both direction at the same time v) Provides token management facility vi) Synchronization of the devices. 6) Presentation Layer : The layer which is concerned with the semantics of the information exchange between the two systems is called presentation layer. Characteristics : i) Translation ii) Encryption iii) Compression iv) Relation between the layers 7) Application Layer : The layer that provides human or user to access the network is called application layer. Characteristics : i) mail-Service ii) File transfer/management iii) Remote log in iv) Directory service v) Access of WWW.