Parcial 2 Flashcards
Protocol layering, packet switching, routing and data streaming are the principies on wich
Computer Networks
The computers and other devices that use the network for communication purposes are refered to as
Host
This is the delay that occurs after a send operation is executed before dta stars to arrive at the destination computer in network performance
Latency
This term is used to refer to any computer or switching device attached to a network
Node
This is the speed at wich data can be transferred between two computers in the network once transmission has begun
Data transfer rate
This is a single communication subsystem providing communication between all of the host that are conected to it, where the internet is constructed from many subnets
The internet
The carry messages at lower speeds between nodes that are often in different organizations and may be separated by large distances
Wide area networks (WANs)
The end-to-end communication must provide totally error-free: the detection of communication errors and their correction is the we call
Reliability
This is a sequence of binary data (an array of bits or bytes) of restricted lenght, together with addressing information sufficient to identify the source and destination computers
The simplest form of packet
This is a unit of routing (delivering data from one part of the internet to another)
Subnet
This type of networks is based on the high bandwith copper and fiber optic cabling recently installed in some towns and cities for the transmission of video, voice and other data over distances of up to 50 kilometers
Metropolitan area networks (MANs)
This is defines as the ability to meet deadlines when transmission and processing streams of real-time multimedia data
Quality of services
This is a communication subsystem in which several networks are linked together to provide common data communication facilities that overlay yhe technologies and protocols of the individual component networks and the methods used to their interconnection
Internetworks
This is why many networks technologies support the simultaneous transmission of messages to several recipients
Multicasting
The IEEE 802.16 WIMAX standars is targeted at this class of network. It aims to provide an alternative to wired connections to home and office buildings.
Wireless metropolitan area networks (WMANs)
This is refered to as the transmission and display of audio and video in real time. It requires much higher handwidths than most other forms of communication in distribuited systems
Data Streaming
They are composed of a number of personal devices such as mobile phones, tablets, digital cameras, music players and so on that are now carried by many people
Wireless personal area networks (WPANs)
They are generally used to hold the video frames, but because the flow is continuous as opposed to the intermittent traffic generated by typical client-server interactions and are handled somewhat differently
UDP internet packets
In this type of network, most mobile phone networks are based on digital wireless network technologies such as the GSM standar, which is used in most countries of the world
Wireless wide area networks (WWAN)
They are specially designed to provide high bandwidth and low latencies and to support quality of services by resrvation of network resources
ATM networks
This is transmission technique that involves no switching, everything is transmitted to every node, and it is up to potential receivers to notice transmissions addressed to them
Broadcats
In this type of switching, each packet arriving at a node is first stored in memory at the node and then processed bya program that transmits it on a outgoing circuit, which transfers the packet to another node that is closer to its ultimate destination
Packet switching
Their operation was simple to understand, when a caller dialed a number, the pair of wires from her phone to the local exchange was connected by an automatic switch at the exchange to the pair of wires connectedthe other party’s phone
Circuit switching
This is used to refer to a well-know set of rules and formats to be used for communication between processes in roder to perform a given task
the term Protocol
The task of dividing messages into packets before transmission and reassembling them at the receiving computer is ussually performed in the transport layer
Packet assembly
They are software-defined destination points at as host computer. They are attached to processes, enabling data transmission to be addressed to a specific process at a destination node
Port / Ports
This is a numeric identifier that uniquely identifies a host computer and enables it to be located by nodes that are responsible for routing data to it
A network address
When a pair of nodes connected to two separate networks need to communicate through another type of network or over an alien protocol, they can do so by construcion a protocol under a scheme of
Tunnel / Tunneling
This is a function that is required in all networks exept those LANs such as the ethernet, that provide direct connections between all pairs of attached hosts
Routing
A unified addressing scheme between different networks that enables packets to be addressing to any host connected to any subnet is an necessary element to build
Internetworking
This must lend itself to the development of a flexible and efficient ruting scheme, but the addresses themselves cannot contain very much of the information needed to route a packet to its destination
The addressing scheme
The determination of routes for the transmission of packets to their destinations is the responsability of this procedure, which has two parts
Routing alforithm
It is based upon the permanent allocation of a normal IP address to each mobile host on a subnet in its home domain
Mobile IP
The purpose of this is to monitor and control all communication into and out of a intranet
Firewall
Message passing between a pair of processes can be support by two messgae communication operations
send and receive operations
In this form of communication, the use of the send operation is non-blocking, the receive operation can have blocking and non-blocking variants
Asynchronous communication
We can describe this as the guarantee to deliver the message despite a reasonable number of packets being dropped or lost
Reliability
Both forms of communication (UDP and TCP)_______, which provides an endpoint for communication between processes
socket abstraction
In this form onf communication , the sending and receiving processes synchonize at every message. In this case, both send and receive are blocking operations
the synchronous communication
Any process may make use of multiple of these elements to receive message, but a process cannot share them with other process on the same computer
Ports
The internet protocols, and the local port pairs define the
Message destination
The consist of transmiting a message between a socket in one process and a socket in another process
Interprocess communication
This is sent by UDP is transmitted from a sending process to a receive process without acknowledgment or retries
Datagram
Messgae may be dropped occasionally, either because of a checksum error or because no buffer space is available at the source or destination, it’s called
Omission failures
This defines reliable communicattion for channels in terms of two properties: integrity and validity
Failure model
This was originated from BSD 4.x UNIX and provides the abstraction of a stream of bytes to wich data may be written and from which data may be read
API to the TCP protocol
This assume that when a pair of processes are establishing a connection, one of them plays the client role and another play the server role, but thereafter the could be peers
The API for stream communication
The TCP protocol uses an acknowledgement scheme. If the sender does not receive an acknowledgement with a time out, it retransmits the messgae and this is performed when
Lost messages
The TCP protocol attempts to match the speeds of the processes that read from and write to a stream, this is called
Flow Control
These items transmitted in messages can be data values of many different types, and not all computers store primitive values such as intergers in the same order
Individual primitive data
This is process of taking a collection of data items and assembling or disassembling (respectively) into a form suitable for transmission in a message
Marshalling and Unmarshalling
They are three alternative approaches to external data representation
XML, CORBA’s, Java’s object serialization
The first one was designed for defining the appearance of web pages while the second one was designed for writing structures documnets for the web
HTML, XML
They are tagged with ‘markup’ strings. the tags are used to describe the logical structure of the data and to associate atribute-vañue pairs witg logical structures
XML data items
XML is _____________ in the sense that users can define theri own tags, in constrast to HTML, which uses a fixed set of tags
Extensible
This is a markup language that was defined by the World Wide Web Consortium (W3C) for general use on the web
XML
The structure of an XML document is defined by pairs of these elements encloses in angle brackets
Tags
They define the name of values associate to tags in XML schemes
XML-Attributes
This is used to enable clients to communicate with web services and for defining the interfaces and other properties of web services
XML-Service
All of the information in XML elements must be expressed as character data. but teh question is how do we represent encrypted elements or secure hashes?
Binary data
Every start tag has a matching end tag and all tags are correctly nested, these are
Basic Rules of XML
Every XML document must have this as its first line and must least specify the version XML in use )which is currently 1.0)
Prolog
This is a set of names for a collection of elemt types and distributes that is referenced by a URL
XML namespaces
This defines the elements and attributes that can appear in a document, how the element are nested and the order and number of elements, and whether an element is empty or can include text
XML schema
This protocol is bases on a trio of communication primitives: doOperation getRequest and sendReplay
The request-replay protocol
This scheme invlolves the management of messgaes and requires that each messages have a unique element by which it may be referenced
Message Identifiers
As its name indicates, it is a mechanism to call aprocedure or a function available on a remote computer
*RCP
This uses the HTTP protocol to pass infotmation from a client computer to a server computer and uses a small XML vocabulary to describe the nature of request and responses
*XML-RPC Structure
This specifies a procedure name and paramenters in the XML request, and the server returns either a fault or a response in the XML response
*XML RCP Parameters
Data model, request structures and response structures are parts of
*XML RPC
They are a simple list of types and contet -structs and arrays are the most complex types available
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