Network performance management
Encyclopedia
Factors affecting network performance
Not all networks are the same. As data is broken into component parts (often known frames, packets, or segments) for transmission, several factors can affect their delivery.- LatencyLagLag is a common word meaning to fail to keep up or to fall behind. In real-time applications, the term is used when the application fails to respond in a timely fashion to inputs...
: It can take a long time for a packet to be delivered across intervening networks. In reliable protocols where a receiver acknowledges delivery of each chunk of data, it is possible to measure this as round-trip time. - Packet lossPacket lossPacket loss occurs when one or more packets of data travelling across a computer network fail to reach their destination. Packet loss is distinguished as one of the three main error types encountered in digital communications; the other two being bit error and spurious packets caused due to noise.-...
: In some cases, intermediate devices in a network will lose packets. This may be due to errors, to overloading of the intermediate network, or to intentional discarding of traffic in order to enforce a particular service level. - RetransmissionRetransmissionRetransmission might refer to:* Retransmission , the resending of packets which have been damaged or lost* Replication of a signal at a repeater**re-broadcast through a rebroadcaster or broadcast translator or booster, or relay station...
: When packets are lost in a reliable network, they are retransmitted. This incurs two delays: First, the delay from re-sending the data; and second, the delay resulting from waiting until the data is received in the correct order before forwarding it up the protocol stack. - ThroughputThroughputIn communication networks, such as Ethernet or packet radio, throughput or network throughput is the average rate of successful message delivery over a communication channel. This data may be delivered over a physical or logical link, or pass through a certain network node...
: The amount of traffic a network can carry is measured as throughput, usually in terms such as kilobits per second. Throughput is analogous to the number of lanes on a highway, whereas latency is analogous to its speed limit.
These factors, and others (such as the performance of the network signaling on the end nodes, compression
Data compression
In computer science and information theory, data compression, source coding or bit-rate reduction is the process of encoding information using fewer bits than the original representation would use....
, encryption
Encryption
In cryptography, encryption is the process of transforming information using an algorithm to make it unreadable to anyone except those possessing special knowledge, usually referred to as a key. The result of the process is encrypted information...
, concurrency, and so on) all affect the effective performance of a network. In some cases, the network may not work at all; in others, it may be slow or unusable. And because applications run over these networks, application performance suffers. Various intelligent solutions are available to ensure that traffic over the network is effectively managed to optimize performance for all users. See Traffic Shaping
Traffic shaping
Traffic shaping is the control of computer network traffic in order to optimize or guarantee performance, improve latency, and/or increase usable bandwidth for some kinds of packets by delaying other kinds of packets that meet certain criteria...
The performance management discipline
Network performance management consists of measuring, modeling, planning, and optimizing networks to ensure that they carry traffic with the speed, reliability, and capacity that is appropriate for the nature of the application and the cost constraints of the organization.Different applications warrant different blends of capacity, latency, and reliability. For example:
- Streaming video or voice can be unreliable (brief moments of static) but needs to have very low latency so that lags don't occur
- Bulk file transfer or e-mail must be reliable and have high capacity, but doesn't need to be instantaneous
- Instant messaging doesn't consume much bandwidth, but should be fast and reliable
Network performance management tasks and classes of tools
Network Performance management is a core component of the FCAPSFCAPS
FCAPS is the ISO Telecommunications Management Network model and framework for network management. FCAPS is an acronym for fault, configuration, accounting, performance, security, the management categories into which the ISO model defines network management tasks...
ISO telecommunications framework (the 'P' stands for Performance in this acronym). It enables the network engineers to proactively prepare for degradations in their IT infrastructure and ultimately help the end-user experience.
Network managers perform many tasks; these include performance measurement, forensic analysis, capacity planning, and load-testing or load generation. They also work closely with application developers and IT departments who rely on them to deliver underlying network services.
- For performance measurement, operators typically measure the performance of their networks at different levels. They either use per-port metrics (how much traffic on port 80 flowed between a client and a server and how long did it take) or they rely on end-user metrics (how fast did the login page load for Bob.)
- Per-port metrics are collected using flow-based monitoring and protocols such as NetflowNetflowNetFlow is a network protocol developed by Cisco Systems for collecting IP traffic information. NetFlow has become an industry standard for traffic monitoring and is supported by platforms other than Cisco IOS and NXOS such as Juniper routers, Enterasys Switches, vNetworking in version 5 of...
(now standardized as IPFIX) or RMONRMONThe Remote Network MONitoring MIB was developed by the IETF to support monitoring and protocol analysis of LANs. The original version focused on OSI Layer 1 and Layer 2 information in Ethernet and Token Ring networks...
. - End-user metrics are collected through web logsServer logA server log is a log file automatically created and maintained by a server of activity performed by it.A typical example is a web server log which maintains a history of page requests. The W3C maintains a standard format for web server log files, but other proprietary formats exist...
, synthetic monitoringSynthetic monitoringSynthetic monitoring is website monitoring that is done using a web browser emulation or scripted real web browsers. Behavioral scripts are created to simulate an action or path that a customer or end-user would take on a site...
, or real user monitoringReal user monitoringReal user monitoring is a passive web monitoring technology that records all user interaction with a website. Monitoring actual user interaction with a website is important to website operators to determine if users are being served quickly, error free and if not which part of a business process...
. An example is ART (application response time) which provides end to end statistics that measure Quality of ExperienceQuality of experienceQuality of experience , some times also known as quality of user experience, is a subjective measure of a customer's experiences with a service...
.
- Per-port metrics are collected using flow-based monitoring and protocols such as Netflow
- For forensic analysis, operators often rely on snifferSnifferSniffer may refer to:* Packet analyzer , computer software or hardware that can intercept and log traffic passing over a digital network...
s that break down the transactions by their protocols and can locate problems such as retransmissions or protocol negotiations. - For capacity planning, modeling tools such as OPNETOPNETOPNET Technologies, Inc. is a software business that provides performance analysis for computer networks and applications.The company was founded in 1986 and went public in 2000. It is headquartered in Bethesda, Maryland and has offices in Cary, North Carolina; Nashua, New Hampshire; Dallas,...
, PacketTrapPacketTrapPacketTrap provides network management and traffic analysis software for midsize companies. PacketTrap has offices in Silicon Valley and Calcutta, India.- History :...
, Zyrion TraverseZyrion TraverseZyrion Traverse is a IT Infrastructure & Cloud monitoring software that leverages the concept of Business Service Management using ‘service containers’ for correlating application and network problems. BSM has gained prevalence in the network management arena in recent years...
, Scrutinizer NetFlow and sFlow Analyzer, or NetQoSNetQoSNetQoS Inc. provides network management software and services, including applications for performance management and response time analysis. "QoS" refers to "quality of service." NetQoS Ranked Number 184 Fastest Growing Company in North America on Deloitte’s 2007 Technology Fast 500...
that project the impact of new applications or increased usage are invaluable. - For load generation that helps to understand the breaking point, operators may use software or appliances that generate scripted traffic. Some hosted service providers also offer pay-as-you-go traffic generation for sites that face the public Internet.
See also
- Capacity managementCapacity managementCapacity Management is a process used to manage information technology . Its primary goal is to ensure that IT capacity meets current and future business requirements in a cost-effective manner. One common interpretation of Capacity Management is described in the ITIL framework...
- Capacity planningCapacity planningCapacity planning is the process of determining the production capacity needed by an organization to meet changing demands for its products. In the context of capacity planning, "capacity" is the maximum amount of work that an organization is capable of completing in a given period of time...
- Network planning and designNetwork planning and designNetwork planning and design is an iterative process, encompassingtopological design, network-synthesis, and network-realization, and is aimed at ensuring that a new network or service meets the needs of the subscriber and operator....
- Network monitoringNetwork monitoringThe term network monitoring describes the use of a system that constantly monitors a computer network for slow or failing components and that notifies the network administrator in case of outages...
- Performance engineeringPerformance EngineeringPerformance engineering within systems engineering, encompasses the set of roles, skills, activities, practices, tools, and deliverables applied at every phase of the Systems Development Life Cycle which ensures that a solution will be designed, implemented, and operationally supported to meet the...
- Performance tuningPerformance tuningPerformance tuning is the improvement of system performance. This is typically a computer application, but the same methods can be applied to economic markets, bureaucracies or other complex systems. The motivation for such activity is called a performance problem, which can be real or anticipated....
- Systems engineeringSystems engineeringSystems engineering is an interdisciplinary field of engineering that focuses on how complex engineering projects should be designed and managed over the life cycle of the project. Issues such as logistics, the coordination of different teams, and automatic control of machinery become more...
- Computer Measurement GroupComputer Measurement GroupThe Computer Measurement Group , founded in 1974, is a worldwide non-profit organization of data processing professionals whose work involves measuring and managing the performance of computing systems...