Catalyst is the brand for a variety of network switches , wireless controllers, and wireless access points sold by Cisco Systems . While commonly associated with Ethernet switches, a number of different types of network interfaces have been available throughout the history of the brand. Cisco acquired several different companies and rebranded their products as different versions of the Catalyst product line. The original Catalyst 5000 and 6000 series were based on technology acquired from Crescendo Communications . The 1700, 1900, and 2800 series Catalysts came from Grand Junction Networks , and the Catalyst 3000 series came from Kalpana in 1994.
72-547: The newest Catalyst series is the Catalyst 9000 family. The Catalyst 9000 family includes switches, wireless access points, and wireless controllers. In most cases, the technology for the Catalyst Switch was developed separately from Cisco's router technology. The Catalyst switches originally ran software called CatOS rather than the more widely known Cisco IOS software used by routers. However, this has changed as
144-679: A Trivial File Transfer Protocol (TFTP) server for storing the configuration files and any IOS images for updating. Complex configurations are best created using a text editor (using a site standard template), putting the file on the TFTP server and copying it to the Cisco device. However, it can be noted that a TFTP server can present its own security problems. StackWise and Stackwise Virtual previously known as VSS are technologies offered by Cisco Systems that allows some models of Catalyst switches to operate as though they were one switch. One switch from
216-417: A router , making them layer 3 devices; when coupled with TCP and UDP filtering, these switches are capable of layer 2-4 operation. Depending on the exact software image, a Catalyst switch that runs IOS or IOS XE may be able to tackle large-scale enterprise routing tasks, using router technologies like OSPF or BGP . Modular chassis-based Catalyst switching models, like the Catalyst 9400 and 9600 Series, have
288-411: A serial console , telnet or Secure Shell . Simple Network Management Protocol (SNMP) allows monitoring of many states, and measurement of traffic flows. Many devices can also run an HTTP server . Configuration of the switch is done in plain text and is thus easy to audit. No special tools are required to generate a useful configuration. For sites with more than a few devices, it is useful to set up
360-424: A simple early form of HTML , from web server(s) using a new basic communication protocol that was named HTTP 0.9 . In August 1991 Tim Berners-Lee announced the birth of WWW technology and encouraged scientists to adopt and develop it. Soon after, those programs, along with their source code , were made available to people interested in their usage. Although the source code was not formally licensed or placed in
432-452: A Linux-based operating system. The IOS network operating system was created from code written by William Yeager at Stanford University , which was developed in the 1980s for routers with 256 kB of memory and low CPU processing power. Through modular extensions, IOS has been adapted to increasing hardware capabilities and new networking protocols. When IOS was developed, Cisco Systems' main product line were routers. The company acquired
504-526: A basis for general computer-to-computer communication, as well as support for WebDAV extensions, have extended the application of web servers well beyond their original purpose of serving human-readable pages. This is a very brief history of web server programs , so some information necessarily overlaps with the histories of the web browsers , the World Wide Web and the Internet ; therefore, for
576-473: A configurable selection of chassis, power supplies, line cards and supervisor modules. Among Cisco's modular series are: Announced 2020 (remainder including 2960-X & 2960-XR) 24/48 8P8C/2 X2 (3750E) Announced 2013 (3750V2) 9200L 9300L Cisco IOS The Internetworking Operating System ( IOS ) is a family of proprietary network operating systems used on several router and network switch models manufactured by Cisco Systems . The system
648-644: A later major revision because they may be running critical infrastructure on their devices, and hence prefer to minimize change and risk. Interim releases – Are usually produced on a weekly basis, and form a roll-up of current development effort. The Cisco advisory web site may list more than one possible interim to fix an associated issue (the reason for this is unknown to the general public). Maintenance releases – Rigorously tested releases that are made available and include enhancements and bug fixes. Cisco recommend upgrading to Maintenance releases where possible, over Interim and Rebuild releases. Cisco says, "A train
720-816: A local account is usually still required for emergency situations. At the Black Hat Briefings conference in July 2005, Michael Lynn, working for Internet Security Systems at the time, presented information about a vulnerability in IOS. Cisco had already issued a patch, but asked that the flaw not be disclosed. Cisco filed a lawsuit, but settled after an injunction was issued to prevent further disclosures. With IOS being phased out on devices, IOS-XE adopted many improvements including updated defaults. Some use cases can now store secrets as one-way hashes . For Cisco products that required very high availability, such as
792-1064: A long time and so Apache suffered, even more, the competition of commercial servers and, above all, of other open-source servers which meanwhile had already achieved far superior performances (mostly when serving static content) since the beginning of their development and at the time of the Apache decline were able to offer also a long enough list of well tested advanced features. In fact, a few years after 2000 started, not only other commercial and highly competitive web servers, e.g. LiteSpeed , but also many other open-source programs, often of excellent quality and very high performances, among which should be noted Hiawatha , Cherokee HTTP server , Lighttpd , Nginx and other derived/related products also available with commercial support, emerged. Around 2007–2008, most popular web browsers increased their previous default limit of 2 persistent connections per host-domain (a limit recommended by RFC-2616) to 4, 6 or 8 persistent connections per host-domain, in order to speed up
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#1732775767515864-536: A number of young companies that focused on network switches, such as the inventor of the first Ethernet switch Kalpana , and as a result Cisco switches did not initially run IOS. Prior to IOS, the Cisco Catalyst series ran CatOS . The IOS command-line interface (CLI) provides a fixed set of multiple-word commands . The set available is determined by the "mode" and the privilege level of the current user. "Global configuration mode" provides commands to change
936-509: A particular function can be determined using the Cisco Feature Navigator . Routers come with IP Base installed, and additional feature pack licenses can be installed as bolt-on additions to expand the feature set of the device. The available feature packs are: IOS images can not be updated with software bug fixes. To patch a vulnerability in IOS, a binary file with the entire operating system needs to be loaded. Cisco IOS
1008-514: A physical file system path, to an absolute path under the target website's root directory. Website's root directory may be specified by a configuration file or by some internal rule of the web server by using the name of the website which is the host part of the URL found in HTTP client request. Path translation to file system is done for the following types of web resources: The web server appends
1080-464: A stack is elected in the following order: There are two general types of Catalyst switches: fixed configuration models that are usually one or two rack units in size, with 12 to 80 ports; and modular switches in which virtually every component, from the CPU card to power supplies to switch cards, are individually installed in a chassis. In general, switch model designations start with WS-C or C, followed by
1152-428: A strong impetus to the adoption of reverse proxies in front of slower web servers and it gave also one more chance to the emerging new web servers that could show all their speed and their capability to handle very high numbers of concurrent connections without requiring too many hardware resources (expensive computers with lots of CPUs, RAM and fast disks). In 2015, RFCs published new protocol version [HTTP/2], and as
1224-422: A unique reference to that interface. IOS is shipped as a unique file that has been compiled for specific Cisco network devices. Each IOS Image therefore include a feature set, which determine the command-line interface (CLI) commands and features that are available on different Cisco devices. Upgrading to another feature set therefore entails the installation of a new IOS image on the networking device and reloading
1296-451: A web server and some of the tasks that it may perform in order to have a sufficiently wide scenario about the topic. A web server program plays the role of a server in a client–server model by implementing one or more versions of HTTP protocol, often including the HTTPS secure variant and other features and extensions that are considered useful for its planned usage. The complexity and
1368-438: A web server can be a pre-existing file ( static content ) available to the web server, or it can be generated at the time of the request ( dynamic content ) by another program that communicates with the server software. The former usually can be served faster and can be more easily cached for repeated requests, while the latter supports a broader range of applications. Technologies such as REST and SOAP , which use HTTP as
1440-427: A web server implements one or more of the above-mentioned advanced features then the path part of a valid URL may not always match an existing file system path under website directory tree (a file or a directory in file system ) because it can refer to a virtual name of an internal or external module processor for dynamic requests. Web server programs are able to translate an URL path (all or part of it), that refers to
1512-467: Is computer software and underlying hardware that accepts requests via HTTP (the network protocol created to distribute web content ) or its secure variant HTTPS . A user agent, commonly a web browser or web crawler , initiates communication by making a request for a web page or other resource using HTTP, and the server responds with the content of that resource or an error message . A web server can also accept and store resources sent from
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#17327757675151584-421: Is a package of routing, switching, internetworking and telecommunications functions integrated into a multitasking operating system. Although the IOS code base includes a cooperative multitasking kernel, most IOS features have been ported to other kernels such as QNX and Linux for use in Cisco products. Cisco Catalyst products run IOS or a Linux-derived version called Cisco IOS XE . It was originally called XDI by
1656-672: Is a package of routing, switching, internetworking, and telecommunications functions integrated into a multitasking operating system. Although the IOS code base includes a cooperative multitasking kernel, most IOS features have been ported to other kernels, such as Linux and QNX , for use in Cisco products. Not all Cisco networking products run IOS. Exceptions include some Cisco Catalyst switches, which run IOS XE , and Cisco ASR routers, which run either IOS XE or IOS XR ; both are Linux-based operating systems. For data center environments, Cisco Nexus switches ( Ethernet ) and Cisco MDS switches ( Fibre Channel ) both run Cisco NX-OS , also
1728-504: Is a vehicle for delivering Cisco software to a specific set of platforms and features." Before Cisco IOS release 15, releases were split into several trains , each containing a different set of features. Trains more or less map onto distinct markets or groups of customers that Cisco targeted. There were other trains from time to time, designed for specific needs — for example, the 12.0AA train contained new code required for Cisco's AS5800 product. Starting with Cisco IOS release 15, there
1800-505: Is just a single train, the M/T train. This train includes both extended maintenance releases and standard maintenance releases. The M releases are extended maintenance releases, and Cisco will provide bug fixes for 44 months. The T releases are standard maintenance releases, and Cisco will only provide bug fixes for 18 months. Because IOS needs to know the cleartext password for certain uses, (e.g., CHAP authentication) passwords entered into
1872-568: Is no memory protection between processes and IOS has a run to completion scheduler , which means that the kernel does not pre-empt a running process . Instead the process must make a kernel call before other processes get a chance to run. IOS considers each process a single thread and assigns it a priority value, so that high priority processes are executed on the CPU before queued low priority processes, but high priority processes cannot interrupt running low priority processes. The Cisco IOS monolithic kernel does not implement memory protection for
1944-481: Is referring to, so that that resource can be returned to the requesting client. This process is performed with every request that is made to a web server, with some of the requests being served with a file, such as an HTML document, or a gif image, others with the results of running a CGI program, and others by some other process, such as a built-in module handler, a PHP document, or a Java servlet." In practice, web server programs that implement advanced features, beyond
2016-425: Is used by the forwarding function of the router. On router platforms with software-only forwarding (e.g., Cisco 7200), most traffic handling, including access control list filtering and forwarding, is done at interrupt level using Cisco Express Forwarding (CEF) or dCEF (Distributed CEF). This means IOS does not have to do a process context switch to forward a packet. Routing functions such as OSPF or BGP run at
2088-403: Is versioned using three numbers and some letters, in the general form a.b(c.d)e , where: Rebuilds – Often a rebuild is compiled to fix a single specific problem or vulnerability for a given IOS version. For example, 12.1(8)E14 is a Rebuild, the 14 denoting the 14th rebuild of 12.1(8)E. Rebuilds are produced to either quickly repair a defect, or to satisfy customers who do not want to upgrade to
2160-601: The CGI to communicate with external programs. These capabilities, along with the multimedia features of NCSA's Mosaic browser (also able to manage HTML FORMs in order to send data to a web server) highlighted the potential of web technology for publishing and distributed computing applications. In the second half of 1994, the development of NCSA httpd stalled to the point that a group of external software developers, webmasters and other professional figures interested in that server, started to write and collect patches thanks to
2232-693: The Cisco CRS-1 , the limitations of a monolithic kernel were not acceptable. In addition, competitive router operating systems that emerged 10–20 years after IOS, such as Juniper 's Junos OS , were designed to not have these limitations. Cisco's response was to develop a completely new operating system that offered modularity, memory protection between processes, lightweight threads, pre-emptive scheduling , ability to independently restart failed processes and massive scale for use in Service Provider networks. The IOS XR development train initially used
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2304-480: The public domain . This statement freed web server developers from any possible legal issue about the development of derivative work based on that source code (a threat that in practice never existed). At the beginning of 1994, the most notable among new web servers was NCSA httpd which ran on a variety of Unix -based OSs and could serve dynamically generated content by implementing the POST HTTP method and
2376-534: The real-time operating system microkernel ( QNX ) and a large part of the IOS source code was re-written to take advantage of the features offered by the kernel. In 2005 Cisco introduced the Cisco IOS XR network operating system on the 12000 series of network routers, extending the microkernel architecture from the CRS-1 routers to Cisco's widely deployed core routers . As of release 6.x of Cisco IOS XR, QNX
2448-458: The CLI by default are weakly encrypted as 'Type 7' ciphertext, such as " Router(config)#username jdoe password 7 0832585B1910010713181F ". This is designed to prevent "shoulder-surfing" attacks when viewing router configurations and is not secure – they are easily decrypted using software called "getpass" available since 1995, or "ios7crypt", a modern variant, although the passwords can be decoded by
2520-677: The Cisco IOS) also allow web-based management using a graphical interface (GUI) module which is hosted on a HTTP server located on the switch. The Catalyst 2960-L SM Series of switches is an example of a Cisco Catalyst switch that allows this style of GUI via HTTP. Cisco IOS , formally the Cisco Internetwork Operating System, is a family of network operating systems used on many Cisco Systems network switches, routers, wireless controllers and wireless access points. Earlier, Cisco switches ran CatOS. Cisco IOS
2592-583: The IOS operating system. Information about the IOS version and feature-set running on a Cisco device can be obtained with the show version command. Most Cisco products that run IOS also have one or more "feature sets" or "packages", typically eight packages for Cisco routers and five packages for Cisco network switches. For example, Cisco IOS releases meant for use on Catalyst switches are available as "standard" versions (providing only basic IP routing), "enhanced" versions, which provide full IPv4 routing support, and "advanced IP services" versions, which provide
2664-541: The IP address, interface state, and packet statistics for networking data. Cisco's IOS software maintains one IDB for each hardware interface in a particular Cisco switch or router and one IDB for each subinterface. The number of IDBs present in a system varies with the Cisco hardware platform type. Physical and logical interfaces on the switch will be referenced with either expanded or abbreviated port description names. This combined with slot, module, and interface numbering creates
2736-629: The NCSA httpd source code being available to the public domain. At the beginning of 1995 those patches were all applied to the last release of NCSA source code and, after several tests, the Apache HTTP server project was started. At the end of 1994, a new commercial web server, named Netsite , was released with specific features. It was the first one of many other similar products that were developed first by Netscape , then also by Sun Microsystems , and finally by Oracle Corporation . In mid-1995,
2808-537: The availability of new protocol , not only because they had the work force and the time to do so, but also because usually their previous implementation of SPDY protocol could be reused as a starting point and because most used web browsers implemented it very quickly for the same reason. Another reason that prompted those developers to act quickly was that webmasters felt the pressure of the ever increasing web traffic and they really wanted to install and to try – as soon as possible – something that could drastically lower
2880-517: The concept of field-replaceable supervisor, line cards, power supplies and fans. Mirroring most Cisco router designs, these work by separating the line cards, chassis, and supervisor engine . The chassis provides power and a high-speed backplane , the line cards provide interfaces to the network, and the supervisor engine moves packets, participates in routing protocols, etc. This gives several advantages: Catalyst switches offer advanced customization and manageability. The switches can be configured using
2952-424: The data of different processes. The entire physical memory is mapped into one virtual address space. The Cisco IOS kernel does not perform any memory paging or swapping. Therefore the addressable memory is limited to the physical memory of the network device on which the operating system is installed. IOS does however support aliasing of duplicated virtual memory contents to the same physical memory. This architecture
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3024-870: The efficiency of a web server program may vary a lot depending on (e.g.): Although web server programs differ in how they are implemented, most of them offer the following common features. These are basic features that most web servers usually have. A few other more advanced and popular features ( only a very short selection ) are the following ones. A web server program, when it is running, usually performs several general tasks , (e.g.): Web server programs are able: Once an HTTP request message has been decoded and verified, its values can be used to determine whether that request can be satisfied or not. This requires many other steps, including security checks . Web server programs usually perform some type of URL normalization ( URL found in most HTTP request messages) in order to: The term URL normalization refers to
3096-481: The enhanced features as well as IPv6 support. Beginning with the 1900, 2900 and 3900 series of ISR Routers, Cisco revised the licensing model of IOS. To simplify the process of enlarging the feature-set and reduce the need for network operating system reloads, Cisco introduced universal IOS images, that include all features available for a device and customers may unlock certain features by purchasing an additional software license . The exact feature set required for
3168-499: The event of an IOS crash, the operating system automatically reboots and reloads the saved configuration. In all versions of Cisco IOS, packet routing and forwarding ( switching ) are distinct functions. Routing and other protocols run as Cisco IOS processes and contribute to the Routing Information Base (RIB). This is processed to generate the final IP forwarding table (FIB, Forwarding Information Base), which
3240-406: The first version of IIS was released, for Windows NT OS, by Microsoft . This marked the entry, in the field of World Wide Web technologies, of a very important commercial developer and vendor that has played and still is playing a key role on both sides (client and server) of the web. In the second half of 1995, CERN and NCSA web servers started to decline (in global percentage usage) because of
3312-483: The implementation of new specifications was not trivial at all, a dilemma arose among developers of less popular web servers (e.g. with a percentage of usage lower than 1% .. 2%), about adding or not adding support for that new protocol version. In fact supporting HTTP/2 often required radical changes to their internal implementation due to many factors (practically always required encrypted connections, capability to distinguish between HTTP/1.x and HTTP/2 connections on
3384-441: The interpreter can be scripted to react to events within the networking environment, such as interface failure or periodic timers. Available command modes include: And more than 100 configuration modes and submodes. Cisco IOS has a monolithic architecture, owing to the limited hardware resources of routers and switches in the 1980s. This means that all processes have direct hardware access to conserve CPU processing time. There
3456-408: The maximum number of concurrent connections allowed and to improve their level of scalability. Between 1996 and 1999, Netscape Enterprise Server and Microsoft's IIS emerged among the leading commercial options whereas among the freely available and open-source programs Apache HTTP Server held the lead as the preferred server (because of its reliability and its many features). In those years there
3528-405: The model line (e.g. C9600). A letter at the end of this number signifies a special feature, followed by the number of ports (usually 24 or 48) and additional nomenclature indicating other features like UPOE (e.g. C9300-48U). Catalyst 9000 switches also include software subscription license indicators (e.g. C9200-48T-P, E for Essentials, A for Advantage and P for Premier) Cisco modular switches offer
3600-643: The model. Other models can support T1 , E1 , and ISDN PRI interfaces to provide connections to the PSTN . Legacy models supported a variety of interfaces, such as Token Ring , FDDI , Asynchronous Transfer Mode and 100BaseVG , but are no longer sold by Cisco Systems. All models have basic layer 2 functions and are capable of switching Ethernet frames between ports. Commonly found additional features are VLANs , trunking and QoS . The switches, whether IOS or IOS XE, are fully manageable. Many Catalyst switches that run IOS or IOS XE are also capable of functioning as
3672-406: The new switch on-the-fly to accommodate minimal downtime and reduce maintenance effort and errors. Stackwise physically connects the switch stack using special stack interconnect cables, typically up to eight switches per stack. StackWise Virtual and VSS allow for the virtual clustering of two chassis together into a single, logical entity without physical interconnect cables. The primary switch of
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#17327757675153744-500: The number of TCP/IP connections and speedup accesses to hosted websites. In 2020–2021 the HTTP/2 dynamics about its implementation (by top web servers and popular web browsers) were partly replicated after the publication of advanced drafts of future RFC about HTTP/3 protocol. The following technical overview should be considered only as an attempt to give a few very limited examples about some features that may be implemented in
3816-424: The primary switch fails, another switch in the stack will automatically take over as primary. This feature means greater redundancy, as one switch's failure will not bring about a failure of the entire stack. As each switch contains the entire configuration for the stack, one of the benefits of this technology is the ability to replace a faulty switch (any—including primary) with a new switch. The stack will configure
3888-455: The process level. In routers with hardware-based forwarding, such as the Cisco 12000 series, IOS computes the FIB in software and loads it into the forwarding hardware (such as an ASIC or network processor), which performs the actual packet forwarding function. An Interface Descriptor Block, or simply IDB, is a portion of memory or Cisco IOS internal data structure that contains information such as
3960-431: The process of modifying and standardizing a URL in a consistent manner. There are several types of normalization that may be performed, including the conversion of the scheme and host to lowercase. Among the most important normalizations are the removal of "." and ".." path segments and adding trailing slashes to a non-empty path component. "URL mapping is the process by which a URL is analyzed to figure out what resource it
4032-497: The product lines have merged closer together. In some cases, particularly in the modular chassis switches, a configuration called hybrid has emerged - this is where the layer 2 functions are configured using CatOS, and the layer 3 elements are configured using IOS. Native IOS can also be found with newer software versions that have eliminated CatOS entirely in favor of IOS, even on hardware that originally required CatOS. Some newer Catalyst switch models (with recent versions of
4104-543: The public domain, CERN informally allowed users and developers to experiment and further develop on top of them. Berners-Lee started promoting the adoption and the usage of those programs along with their porting to other operating systems . In December 1991, the first web server outside Europe was installed at SLAC (U.S.A.). This was a very important event because it started trans-continental web communications between web browsers and web servers. In 1991–1993, CERN web server program continued to be actively developed by
4176-429: The retrieval of heavy web pages with lots of images, and to mitigate the problem of the shortage of persistent connections dedicated to dynamic objects used for bi-directional notifications of events in web pages. Within a year, these changes, on average, nearly tripled the maximum number of persistent connections that web servers had to manage. This trend (of increasing the number of persistent connections) definitely gave
4248-505: The router using the "key chain" command and entering the type 7 password as the key, and then issuing a "show key" command; the above example decrypts to "stupidpass". However, the program will not decrypt 'Type 5' passwords or passwords set with the enable secret command, which uses salted MD5 hashes . Cisco recommends that all Cisco IOS devices implement the authentication, authorization, and accounting (AAA) security model. AAA can use local, RADIUS , and TACACS+ databases. However,
4320-438: The sake of clarity and understandability, some key historical information below reported may be similar to that found also in one or more of the above-mentioned history articles. In March 1989, Sir Tim Berners-Lee proposed a new project to his employer CERN , with the goal of easing the exchange of information between scientists by using a hypertext system. The proposal titled "HyperText and CERN" , asked for comments and it
4392-416: The same TCP port, binary representation of HTTP messages, message priority, compression of HTTP headers, use of streams also known as TCP/IP sub-connections and related flow-control, etc.) and so a few developers of those web servers opted for not supporting new HTTP/2 version (at least in the near future) also because of these main reasons: Instead, developers of most popular web servers, rushed to offer
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#17327757675154464-426: The simple static content serving (e.g. URL rewrite engine, dynamic content serving), usually have to figure out how that URL has to be handled, e.g. as a: One or more configuration files of web server may specify the mapping of parts of URL path (e.g. initial parts of file path , filename extension and other path components) to a specific URL handler (file, directory, external program or internal module). When
4536-412: The stack will act as the primary switch. The primary switch will maintain the stack and allows for configuration and monitoring of the whole stack as though one via a single console. This allows for more efficient management and typically provides more bandwidth between individual switches than other uplink technology. If one switch fails, the remaining switches will continue to operate by bypassing it. If
4608-501: The switching company Crescendo Communications, Inc. Cisco renamed it to CatOS when they acquired Crescendo and later still to Cisco IOS as the operating system was extended to other Cisco products. The newer Catalyst 9000 family uses the Cisco IOS XE operating system. As Catalyst devices are primarily Ethernet switches, all modern Catalyst models have Ethernet interfaces ranging from 10 Mbit/s to 100 Gbit/s depending on
4680-433: The system's configuration, and "interface configuration mode" provides commands to change the configuration of a specific interface. All commands are assigned a privilege level , from 0 to 15, and can only be accessed by users with the necessary privilege. Through the CLI, the commands available to each privilege level can be defined. Most builds of IOS include a Tcl interpreter. Using the embedded event manager feature,
4752-431: The user agent if configured to do so. The hardware used to run a web server can vary according to the volume of requests that it needs to handle. At the low end of the range are embedded systems , such as a router that runs a small web server as its configuration interface. A high-traffic Internet website might handle requests with hundreds of servers that run on racks of high-speed computers. A resource sent from
4824-720: The widespread adoption of new web servers which had a much faster development cycle along with more features, more fixes applied, and more performances than the previous ones. At the end of 1996, there were already over fifty known (different) web server software programs that were available to everybody who wanted to own an Internet domain name and/or to host websites. Many of them lived only shortly and were replaced by other web servers. The publication of RFCs about protocol versions HTTP/1.0 (1996) and HTTP/1.1 (1997, 1999), forced most web servers to comply (not always completely) with those standards. The use of TCP/IP persistent connections (HTTP/1.1) required web servers both to increase
4896-418: The www group, meanwhile, thanks to the availability of its source code and the public specifications of the HTTP protocol, many other implementations of web servers started to be developed. In April 1993, CERN issued a public official statement stating that the three components of Web software (the basic line-mode client, the web server and the library of common code), along with their source code , were put in
4968-817: Was also another commercial, highly innovative and thus notable web server called Zeus ( now discontinued ) that was known as one of the fastest and most scalable web servers available on market, at least till the first decade of 2000s, despite its low percentage of usage. Apache resulted in the most used web server from mid-1996 to the end of 2015 when, after a few years of decline, it was surpassed initially by IIS and then by Nginx. Afterward IIS dropped to much lower percentages of usage than Apache (see also market share ). From 2005–2006, Apache started to improve its speed and its scalability level by introducing new performance features (e.g. event MPM and new content cache). As those new performance improvements initially were marked as experimental, they were not enabled by its users for
5040-472: Was dropped in favor of Linux. Part of the initial work focused on modularity inspired modification of monolithic IOS into modular IOS, which extends the microkernel architecture into the IOS environment, while still providing the software upgrade capabilities. That idea was only tested on Catalyst 6500, got limited exposure and was quickly discontinued as requirements were too high and significantly impaired platform operation. HTTP server A web server
5112-414: Was implemented by Cisco in order to ensure system performance and minimize the operational overheads of the operating system. The disadvantage of the IOS architecture is that it increases the complexity of the operating system, data corruption is possible as one process can write over the data of another, and one process can destabilize the entire operating system or even cause a software-forced crash . In
5184-510: Was read by several people. In October 1990 the proposal was reformulated and enriched (having as co-author Robert Cailliau ), and finally, it was approved. Between late 1990 and early 1991 the project resulted in Berners-Lee and his developers writing and testing several software libraries along with three programs, which initially ran on NeXTSTEP OS installed on NeXT workstations: Those early browsers retrieved web pages written in
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