Cisco 1800 Router

Nortel ERS 8600

Cisco 7600 Routers

A router (pronounced /'rautər/ in the USA and Australia, and pronounced /'ru:tər/ in the UK) is a computer whose software and hardware are usually tailored to the tasks of routing and forwarding information. Routers generally contain a specialized operating system (e.g. Cisco's IOS or Juniper Networks JUNOS and JUNOSe or Extreme Networks XOS), RAM, NVRAM, flash memory, and one or more processors. High-end routers contain many processors and specialized Application-specific integrated circuits (ASIC) and do a great deal of parallel processing. Chassis based systems like the Nortel MERS-8600 or ERS-8600 routing switch, (pictured right) have multiple ASICs on every module and allow for a wide variety of LAN, MAN, METRO, and WAN port technologies or other connections that are customizable. Much simpler routers are used where cost is important and the demand is low, for example in providing a home internet service. With appropriate software (such as SmoothWall, XORP or Quagga), a standard PC can act as a router. A D-handle fixed-base router A router is a woodworking tool used to rout out (hollow out) an area in the face of a piece of wood. ... A residential gateway is a hardware device connecting a home network with a wide area network (WAN) or the Internet. ... PCB Layout Program Electronic design automation (EDA) is the category of tools for designing and producing electronic systems ranging from printed circuit boards (PCBs) to integrated circuits. ... Routing is a crucial step in the design of integrated circuits. ... Image File history File links No higher resolution available. ... Image File history File links No higher resolution available. ... Image File history File links No higher resolution available. ... Image File history File links No higher resolution available. ... ERS 8600 Nortel Ethernet Routing Switch 8600 or ERS 8600 (previously named Passport 8600) is a modular chassis combination router and switch manufactured by Nortel. ... Image File history File links No higher resolution available. ... Image File history File links No higher resolution available. ... This article is about the machine. ... This article is about routing in computer networks. ... This article describes routing in computer networks, a method of finding paths from origins to destinations, along which information can be passed. ... An operating system (OS) is a software that manages computer resources and provides programmers with an interface used to access those resources. ... Cisco redirects here. ... Cisco IOS (originally Internetwork Operating System) is the software used on the vast majority of Cisco Systems routers and all current Cisco network switches. ... Juniper Networks NASDAQ: JNPR is a telecommunications equipment company. ... Extreme Networks, is a creator of enterprise level switching routers. ... RAM redirects here. ... It has been suggested that this article or section be merged with Non-volatile memory. ... A USB flash drive. ... CPU redirects here. ... This article does not cite any references or sources. ... Parallel processing is the ability of the brain to simultaneously process incoming stimuli. ... Northern Telecommunications Networks, commonly known as Nortel, is a telecommunications equipment manufacturer headquartered in Canada. ... Metro Ethernet Routing Switch 8600 or MERS 8600 is a modular chassis router and/or switch manufactured by Nortel. ... ERS 8600 Nortel Ethernet Routing Switch 8600 or ERS 8600 (previously named Passport 8600) is a modular chassis combination router and switch manufactured by Nortel. ... Lan can stand for several things: A local area network Lan (airline) formerly LanChile Lan Peru Län, a kind of administrative division used in Sweden Lan Mandragoran, a fictional character in the Wheel of Time fantasy series by Robert Jordan. ... Metropolitan area networks, or MANs, are large computer networks usually spanning a city. ... Wide Area Network (WAN) is a computer network that covers a broad area (i. ... SmoothWall is a firewall distribution based on the GNU/Linux operating system. ... XORP, or Extensible Open Router Platform, is a project to create open source routing system. ... Quagga is a free software routing suite, providing implementations of OSPF (v2 & v3), RIP (v1, v2 & v3) and BGP (v4) for Unix platforms, particularly FreeBSD, GNU/Linux, Solaris and NetBSD. Quagga is a fork of the GNU Zebra project (inactive since 2003) which was developed by Kunihiro Ishiguro. ...

Routers connect two or more logical subnets, which do not necessarily map one-to-one to the physical interfaces of the router.^[1] The term layer 3 switch often is used interchangeably with router, but switch is really a general term without a rigorous technical definition. In marketing usage, it is generally optimized for Ethernet LAN interfaces and may not have other physical interface types. A graphic representation of relationships and source of the various variables representing a chunk of C subnets In computer networks, a subnetwork or subnet is a range of logical addresses within the address space that is assigned to an organization. ... A network switch is a computer networking device that connects network segments. ...

Routers operate in two different planes ^[2]:

• Control Plane, in which the router learns the outgoing interface that is most appropriate for forwarding specific packets to specific destinations,
• Forwarding Plane, which is responsible for the actual process of sending a packet received on a logical interface to an outbound logical interface.

In routing, the control plane defines the part of the router architecture that is concerned with drawing the network map, or the information in a (possibly augmented) routing table that defines what to do with incoming packets. ... In routing, the forwarding plane defines the part of the router architecture that decides what to do with packets arriving on an inbound interface. ...

Control Plane

Main article: Control Plane

Routers are like intersections whereas switches are like streets.

Control Plane processing leads to the construction of what is variously called a routing table or routing information base (RIB). The RIB may be used by the Forwarding Plane to look up the outbound interface for a given packet, or, depending on the router implementation, the Control Plane may populate a separate Forwarding Information Base (FIB) with destination information. RIBs are optimized for efficient updating with control mechanisms such as routing protocols, while FIBs are optimized for the fastest possible lookup of the information needed to select the outbound interface. In routing, the control plane defines the part of the router architecture that is concerned with drawing the network map, or the information in a (possibly augmented) routing table that defines what to do with incoming packets. ... Image File history File links Download high resolution version (1070x703, 12 KB) Summary Router/Switch and Neighborhood Analogy. ... Image File history File links Download high resolution version (1070x703, 12 KB) Summary Router/Switch and Neighborhood Analogy. ... In computer networking a routing table is an electronic table (file) or database type object that is stored in a router or a networked computer. ... This article or section is in need of attention from an expert on the subject. ... Routing protocols allow different computer networks to communicate. ...

The Control Plane constructs the routing table from knowledge of the up/down status of its local interfaces, from hard-coded static routes, and from exchanging routing protocol information with other routers. It is not compulsory for a router to use routing protocols to function, if for example it was configured solely with static routes. The routing table stores the best routes to certain network destinations, the "routing metrics" associated with those routes, and the path to the next hop router. Static routing describes a system that does not implement adaptive routing. ... The introduction to this article provides insufficient context for those unfamiliar with the subject matter. ...

Routers do maintain state on the routes in the RIB/routing table, but this is quite distinct from not maintaining state on individual packets that have been forwarded. In information processing, a state is the complete set of properties (for example, its energy level, etc. ...

Forwarding Plane (a.k.a. Data Plane)

Main article: Forwarding Plane

For the pure Internet Protocol (IP) forwarding function, router design tries to minimize the state information kept on individual packets. Once a packet is forwarded, the router should no longer retain statistical information about it. It is the sending and receiving endpoints that keeps information about such things as errored or missing packets. Aka can refer to the following meanings: Aka is an initialism for Also Known As. ... In routing, the forwarding plane defines the part of the router architecture that decides what to do with packets arriving on an inbound interface. ... The Internet Protocol (IP) is a data-oriented protocol used for communicating data across a packet-switched internetwork. ... In information processing, a state is the complete set of properties (for example, its energy level, etc. ...

Forwarding decisions can involve decisions at layers other than the IP internetwork layer or OSI layer 3. Again, the marketing term switch can be applied to devices that have these capabilities. A function that forwards based on data link layer, or OSI layer 2, information, is properly called a bridge. Marketing literature may call it a layer 2 switch, but a switch has no precise definition. A network bridge connects multiple network segments at the data link layer (layer 2) of the OSI model. ...

Among the most important forwarding decisions is deciding what to do when congestion occurs, i.e., packets arrive at the router at a rate higher than the router can process. Three policies commonly used in the Internet are Tail drop, Random early detection, and Weighted random early detection. Tail drop is the simplest and most easily implemented; the router simply drops packets once the length of the queue exceeds the size of the buffers in the router. Random early detection (RED) probabilistically drops datagrams early when the queue exceeds a configured size. Weighted random early detection requires a weighted average queue size to exceed the configured size, so that short bursts will not trigger random drops. Tail Drop, or Drop Tail, is a simple queue management algorithm. ... Random early detection (RED) is a queue management algorithm. ... Weighted random early detection (WRED) is a queue management algorithm with congestion avoidance capabilities. ...

Types of routers

Cisco CRS-1 Carrier Routing System

Linksys BEFSR41 DSL Router

Routers may provide connectivity inside enterprises, between enterprises and the Internet, and inside Internet Service Providers (ISP). The largest routers (for example the Cisco CRS-1 or Juniper T1600) interconnect ISPs, are used inside ISPs, or may be used in very large enterprise networks. An example of an enterprise router would be the Cisco 7600 (pictured above). The smallest routers provide connectivity for small and home offices (for example the Linksys BEFSR41). Image File history File links No higher resolution available. ... Image File history File links No higher resolution available. ... Carrier Routing System is a new (as of 2004) large scale router, developed by Cisco Systems, Inc. ... Image File history File links No higher resolution available. ... Image File history File links No higher resolution available. ... An Internet Service Provider (ISP) is a business or organization that offers users access to the Internet and related services. ... Cisco redirects here. ... Carrier Routing System is a new (as of 2004) large scale router, developed by Cisco Systems, Inc. ...

Routers for Internet connectivity and internal use

Routers intended for ISP and major enterprise connectivity will almost invariably exchange routing information with the Border Gateway Protocol. RFC 4098^[3] defines several types of BGP-speaking routers: The Border Gateway Protocol (BGP) is the core routing protocol of the Internet. ...

• Provider Edge Router: Placed at the edge of an ISP network, it speaks external BGP (eBGP) to a BGP speaker in another provider or large enterprise Autonomous System (AS).
• Subscriber Edge Router: Located at the edge of the subscriber's network, it speaks eBGP to its provider's AS(s). It belongs to an end user (enterprise) organization.
• Inter-provider Border Router: Interconnecting ISPs, this is a BGP speaking router that maintains BGP sessions with other BGP speaking routers in other providers' ASes.
• Core router: A router that resides within the middle or backbone of the LAN network rather than at its periphery.

Within an ISP: Internal to the provider's AS, such a router speaks internal BGP (iBGP) to that provider's edge routers, other intra-provider core routers, or the provider's inter-provider border routers.

"Internet backbone:" The Internet does not have a clearly identifiable backbone, as did its predecessors. See default-free zone (DFZ). Nevertheless, it is the major ISPs' routers that make up what many would consider the core. These ISPs operate all four types of the BGP-speaking routers described here. In ISP usage, a "core" router is internal to an ISP, and used to interconnect its edge and border routers. Core routers may also have specialized functions in virtual private networks based on a combination of BGP and Multi-Protocol Label Switching (MPLS)^[4].

In the Internet, an autonomous system (AS) is a collection of IP networks and routers under the control of one entity (or sometimes more) that presents a common routing policy to the Internet. ... The Default-free zone refers simultaneously to both the collection of all Internet networks who do not use a defualt route and therefore have full BGP tables and the full BGP tables themselves. ... VPN redirects here. ... In computer networking and telecommunications, Multiprotocol Label Switching (MPLS) is a data-carrying mechanism, operating at a layer below protocols such as IP. It was designed to provide a unified data-carrying service for both circuit-based clients and packet-switching clients which provide a datagram service model. ...

Small Office Home Office (SOHO) connectivity

Main article: Residential gateway

Residential gateways (often called routers) are frequently used in homes to connect to a broadband service, such as IP over cable or DSL. A home router may allow connectivity to an enterprise via a secure Virtual Private Network. A residential gateway is a hardware device connecting a home network with a wide area network (WAN) or the Internet. ... For other uses, see Cable (disambiguation). ... DSL may refer to: Damn Small Linux Dark and Shattered Lands, a MUD based loosely on Forgotten Realms and Dragonlance books. ... VPN redirects here. ...

While functionally similar to routers, residential gateways use network address translation instead of routing. Instead of connecting local computers to the remote network directly, a residential gateway must make local computers appear to be a single computer. In computer networking, Network Address Translation (NAT, also known as Network Masquerading, Native Address Translation or IP Masquerading) is a technique of transceiving network traffic through a router that involves re-writing the source and/or destination IP addresses and usually also the TCP/UDP port numbers of IP packets...

Enterprise Routers

All sizes of routers may be found inside enterprises. While the most powerful routers tend to be found in ISPs, academic and research facilities, as well as large businesses, may need large routers.

A three-layer model is in common use, not all of which need be present in smaller networks ^[5].

Access

Access routers, including SOHO, are located at customer sites such as branch offices that do not need hierarchical routing of their own. Typically, they are optimized for low cost.

Distribution

Distribution routers aggregate traffic from multiple access routers, either at the same site, or to collect the data streams from multiple sites to a major enterprise location. Distribution routers often are responsible for enforcing quality of service across a WAN, so they may have considerable memory, multiple WAN interfaces, and substantial processing intelligence.

They may also provide connectivity to groups of servers or to external networks. In the latter application, the router's functionality must be carefully considered as part of the overall security architecture. Separate from the router may be a Firewall or VPN concentrator, or the router may include these and other security functions. Firewall may refer to: Firewall (construction), a physical barrier inside a building or vehicle, designed to limit the spread of fire, heat and structural collapse Firewall (networking), a logical barrier designed to prevent unauthorized or unwanted communications between sections of a computer network Firewall (film), a 2006 action film written... A Virtual Private Network, or VPN, is a private communications network usually used within a company, or by several different companies or organizations, communicating over a public network. ...

When an enterprise is primarily on one campus, there may not be a distinct distribution tier, other than perhaps off-campus access. In such cases, the access routers, connected to LANs, interconnect via core routers.

Core

In enterprises, core router may provide a "collapsed backbone" interconnecting the distribution tier routers from multiple buildings of a campus, or large enterprise locations. They tend to be optimized for high bandwidth. A core router is a router designed to operate in the Internet backbone, or core. ...

When an enterprise is widely distributed with no central location(s), the function of core routing may be subsumed by the WAN service to which the enterprise subscribes, and the distribution routers become the highest tier.

History

The very first device that had fundamentally the same functionality as a router does today, i.e a packet switch, was the Interface Message Processor (IMP); IMPs were the devices that made up the ARPANET, the first packet switching network. The idea for a router (although they were called "gateways" at the time) initially came about through an international group of computer networking researchers called the International Network Working Group (INWG). Set up in 1972 as an informal group to consider the technical issues involved in connecting different networks, later that year it became a subcommittee of the International Federation for Information Processing. ^[6] A packet switch is a node used to build a network which utilizes the packet switching paradigm for data communication. ... Leonard Kleinrock and the first IMP. Taken from http://www. ... ARPANET logical map, March 1977. ... In computer networking and telecommunications, packet switching is a communications paradigm in which packets (messages or fragments of messages) are individually routed between nodes, with no previously established communication path. ... The International Federation for Information Processing, usually known as IFIP, is an umbrella organization for national societies working in the field of information technology. ...

These devices were different from most previous packet switches in two ways. First, they connected dissimilar kinds of networks, such as serial lines and local area networks. Second, they were connectionless devices, which had no role in assuring that traffic was delivered reliably, leaving that entirely to the hosts (although this particular idea had been previously pioneered in the CYCLADES network). A male DE-9 serial port on the rear panel of a PC. In computing, a serial port consists of an interface on a computer system through which information transfers in or out one bit at a time (contrast parallel port). ... LAN redirects here. ... In a packet-switched network, connectionless mode transmission is transmission in which each packet is prepended with a header containing a destination address sufficient to permit the independent delivery of the packet without the aid of additional instructions. ... The Cyclades (Greek Κυκλάδες) are a Greek island group in the Aegean Sea, south-east of the mainland of Greece; and an administrative prefecture of Greece. ...

The idea was explored in more detail, with the intention to produce real prototype system, as part of two contemporaneous programs. One was the initial DARPA-initiated program, which created the TCP/IP architecture of today. ^[7] The other was a program at Xerox PARC to explore new networking technologies, which produced the PARC Universal Packet system, although due to corporate intellectual property concerns it received little attention outside Xerox until years later. ^[8] The Defense Advanced Research Projects Agency (DARPA) is an agency of the United States Department of Defense responsible for the development of new technology for use by the military. ... The Internet protocol suite is the set of communications protocols that implement the protocol stack on which the Internet runs. ... Bold text // Headline text Link title This article is about the computer research center. ... The PARC Universal Packet (commonly abbreviated to PUP, although the original documents usually use Pup) was one of the two earliest internetwork protocol suites; it was created by researchers at Xerox PARC in the mid-1970s. ...

The earliest Xerox routers came into operation sometime after early 1974. The first true IP router was developed by Virginia Strazisar at BBN, as part of that DARPA-initiated effort, during 1975-1976. By the end of 1976, three PDP-11-based routers were in service in the experimental prototype Internet. ^[9] BBN Technologies (originally Bolt Beranek and Newman) is a high-technology company that provides research and development services. ... The PDP-11 was a 16-bit minicomputer sold by Digital Equipment Corp. ...

The first multiprotocol routers were independently created by staff researchers at MIT and Stanford in 1981; the Stanford router was done by William Yeager, and the MIT one by Noel Chiappa; both were also based on PDP-11s. ^{[10] [11] [12] [13]} “MIT” redirects here. ... Stanford redirects here. ... William Bill Yeager (born June 16, 1940, San Francisco) is an American engineer. ...

As virtually all networking now uses IP at the network layer, multiprotocol routers are largely obsolete, although they were important in the early stages of the growth of computer networking, when several protocols other than TCP/IP were in widespread use. Routers that handle both IPv4 and IPv6 arguably are multiprotocol, but in a far less variable sense than a router that processed AppleTalk, DECnet, IP, and Xerox protocols.

In the original era of routing (from the mid-1970s through the 1980s), general-purpose mini-computers served as routers. Although general-purpose computers can perform routing, modern high-speed routers are highly specialized computers, generally with extra hardware added to accelerate both common routing functions such as packet forwarding and specialised functions such as IPsec encryption. The 1970s decade refers to the years from 1970 to 1979, also called The Seventies. ... The 1980s refers to the years from 1980 to 1989, also called The Eighties. The decade saw social, economic and general upheaval as wealth, production and western culture migrated to new industrializing economies. ... Introduction We all probably heard of supercomputers. ... IPsec (IP security) is a suite of protocols for securing Internet Protocol (IP) communications by authenticating and/or encrypting each IP packet in a data stream. ...

Still, there is substantial use of Linux and Unix machines, running open source routing code, for routing research and selected other applications. While Cisco's operating system was independently designed, other major router operating systems, such as those from Juniper Networks and Extreme Networks, are extensively modified but still have Unix ancestry. This article is about operating systems that use the Linux kernel. ... Filiation of Unix and Unix-like systems Unix (officially trademarked as UNIX®, sometimes also written as or ® with small caps) is a computer operating system originally developed in 1969 by a group of AT&T employees at Bell Labs including Ken Thompson, Dennis Ritchie and Douglas McIlroy. ... Cisco redirects here. ... Juniper Networks NASDAQ: JNPR is a telecommunications equipment company. ... Extreme Networks, is a creator of enterprise level switching routers. ...

See also

Look up router in Wiktionary, the free dictionary.

Wikibooks has a book on the topic of

Computer Networks/Routing

• Core router
• DSL router
• Wireless router
• Wireless bridge
• Access point
• Flapping router
• History of the Internet
• Network address translation (NAT)
• Network bridge
• Network switch
• Hub
• TR-069
• Wi-Fi

Wikipedia does not have an article with this exact name. ... Wiktionary (a portmanteau of wiki and dictionary) is a multilingual, Web-based project to create a free content dictionary, available in over 151 languages. ... Image File history File links Wikibooks-logo-en. ... Wikibooks logo Wikibooks, previously called Wikimedia Free Textbook Project and Wikimedia-Textbooks, is a wiki for the creation of books. ... A core router is a router designed to operate in the Internet backbone, or core. ... Linksys befsr41 DSL Router DSL Routers are a type of router that connect a LAN to the Internet via a DSL connection. ... This article may be too technical for most readers to understand. ... A wireless bridge is used for connecting two or more network segments separated physically, operating on the 802. ... A wireless access point (WAP or AP) is a device that connects wireless communication devices together to create a wireless network. ... In computer networking and telecommunications, a flapping router is a router that transmits routing updates alternately advertising a destination network first via one route, then via a different route. ... Prior to the widespread inter-networking that led to the Internet, most communication networks were limited by their nature to only allow communications between the stations on the network, and the prevalent computer networking method was based on the central mainframe method. ... In computer networking, Network Address Translation (NAT, also known as Network Masquerading, Native Address Translation or IP Masquerading) is a technique of transceiving network traffic through a router that involves re-writing the source and/or destination IP addresses and usually also the TCP/UDP port numbers of IP packets... A network bridge connects multiple network segments at the data link layer (layer 2) of the OSI model. ... A network switch is a computer networking device that connects network segments. ... In general, a hub is a centre point: a wheels hub, which is the center of the wheel with spokes radiating out from it. ... TR-069 (short for Technical Report 069) is a DSL Forum technical specification entitled CPE WAN Management Protocol (CWMP). ... Wi-Fi (IPA: ) is the common name for a popular wireless technology used in home networks, mobile phones, video games and more. ...

External links

• Internet Engineering Task Force, the Routing Area
• Internet Corporation for Assigned Names and Numbers
• North American Network Operators Group
• Réseaux IP Européens (European IP Networks
• American Registry for Internet Numbers
• Asia-Pacific Network Information Center
• Latin American Network Information Center
• African Region Internet Registry

References

1. ^ Requirements for IPv4 Routers,RFC 1812, F. Baker,June 1995
2. ^ Requirements for Separation of IP Control and Forwarding,RFC 3654, H. Khosravi & T. Anderson,November 2003
3. ^ Terminology for Benchmarking BGP Device Convergence in the Control Plane,RFC 4098, H. Berkowitz et al.,June 2005
4. ^ BGP/MPLS VPNs,RFC 2547, E. Rosen and Y. Rekhter,April 2004
5. ^ Oppenheimer, Priscilla (2004). Top-Down Network Design. Indianapolis: Cisco Press. ISBN 1587051524. 
6. ^ Davies, Shanks, Heart, Barker, Despres, Detwiler, and Riml, "Report of Subgroup 1 on Communication System", INWG Note #1.
7. ^ Vinton Cerf, Robert Kahn, "A Protocol for Packet Network Intercommunication", IEEE Transactions on Communications, Volume 22, Issue 5, May 1974, pp. 637 - 648.
8. ^ David Boggs, John Shoch, Edward Taft, Robert Metcalfe, "Pup: An Internetwork Architecture", IEEE Transactions on Communications, Volume 28, Issue 4, April 1980, pp. 612- 624.
9. ^ Craig Partridge, S. Blumenthal, "Data networking at BBN"; IEEE Annals of the History of Computing, Volume 28, Issue 1; January-March 2006.
10. ^ Valley of the Nerds: Who Really Invented the Multiprotocol Router, and Why Should We Care?, Public Broadcasting Service, Accessed August 11, 2007.
11. ^ Router Man, NetworkWorld, Accessed June 22, 2007.
12. ^ David D. Clark, "M.I.T. Campus Network Implementation", CCNG-2, Campus Computer Network Group, M.I.T., Cambridge, 1982; pp. 26.
13. ^ Pete Carey, "A Start-Up's True Tale: Often-told story of Cisco's launch leaves out the drama, intrigue", San Jose Mercury News, December 1, 2001.