The student should become familiar with:
The purpose for standard specifications,
The role of the IEEE,
What each section of the IEEE 802 committee maps to,
The student will learn the sections of the IEEE specification map primarily to be able to distinguish the various technologies and their compatibilities. The information is also required for CompTIA Network+ certification.
The IEEE - Institute of Electrical and Electronic Engineers, is an International standards organization that publishes standards for electrical and electronic manufacturing in particular so that materials, devices and equipment made by different manufacturers will be compatible with each other. This implies an "open architecture" attitude toward all specifications published by the IEEE. The IEEE saw that small computers were on the verge of becoming a very large industry and they knew that users would want to network them as well. So in February of 1980 the IEEE convened to etsablish a committee for publishing computer networking standards that manufacturers could use to develop everything from cabling to network interface cards to low level protocols that all devices would share in common and therefore be compatible with each other facilitating the technologies that already existed at the time. The named the committee the IEEE 802, 80 for the year 1980 and the two for the second month in which the committee was formed. The move could not have been more timely, in the following year the IBM PC would be released and literaly explode into the dominant market of small computers that exists today.
The IEEE 802 committee immediately began to establish a level standard in the existing "Ethernet" technologies many of which were not interoperable though sharing the same names on the cables, connectors, devices, etc. The structure of the data frames exchanged by network tranceivers (the network interface cards of modern netwroked PC's) was developed first. This would become known as the 802.2 subcommittee specification and is also known by its OSI model location. The 802.2 specifies the structure of Layer 2 frames a function defined by the OSI model to be handled by the LLC - Logical Link Control, sublayer. 802.2 is therefore the LLC specification for Ethernet. Ethernet however also needs to have the cables, connectors, actual elecrical properties of the signals on these cables specified along with the topology and the "rules of contention" That is, how will the machines be interconnected physically and how will they vy with each other for control of the cable in order to communicate.
The 802.3 committee would be completed later. This subcommittee lays out the cables, connectors, maximum lengths of cable allowed, electrical properties of the signals, topologies, and the "rules of contention" that the devices will all use. This subcommittee is further broken down into subcommittees as well and originally addressed the three most common technologies already in use on the market at the time. The effort of the IEEE was to make IEEE 802.3 standard equipment compatible with existing equipment as much as possible. This is why any computer industry specifications lag behind the equipment on the shelf and why the specification is then forced to lag even further because manufacturers push forward with manufacturing without a specification template and begin making modifications to a technology which must then be absorbed if possible into the specification. Ethernet had grown and evolved so much by the time the IEEE 802 committee first convened that many independent physical networking technologies had already emerged. These are covered in the 802.3 committee and are known as: 10Base5, 10Base2, and 10BaseT, and 10BaseF respectively. 10BaseF is itself three different sets of Ethernet over fiber optic cable: 10BaseFB which covers a fiber optic backbone used primarily to link 10BaseT hubs or 10Base2 or 10Base5 bridges over distances of up to 2000M (1.24 Miles) apart. 10BaseFL describes linking backbone nodes with fiber optic up to 1000M when interfacing with the older technology called FOIRL (Fiber Optic Inter-Repeater Link) and up to 2000M apart when used exclusively (without any FOIRL nodes). 10BaseFP describes a technology in which end nodes connect to a hub using fiber optic cabling in a star topology. Each 10BaseFP node may be up to 500M from the fiber optic hub.
By the time the 802.3 specifications were published, the computer industry manufacturers were already well on their way to developing 100Mbps Ethernet technologies. These would be added to the 802.3 subcommittee if they used the same "rules of contention" portion of the specification called CSMA/CD - Carrier Sense Multiple Access w/Collision Detection. The specific rules outlined in this specification literally describe Ethernet. This portion of the specification falls into the OSI model at the MAC - Media Access Control sublayer of the Data Link Layer (2) of the model. 802.3u covers the current 100Mbps Ethernet technologies in use today also known as Fast Ethernet. These technologies include 100BaseT, 100BaseTX and 100BaseFX a fiber optic cable based Fast Ethernet in which end nodes may attach to a central connectivity device in a star topology or it may be used to interlink 100BaseTX switches over greater distances than the copper cable can span. The maximum cable length of 100BaseFX is 400M. The differences between 100BaseT (uncommon) and 100BaseTX (the main standard found most often) have to do with the low level function of the nodes. 100BaseT nodes transmit link pulses over the bus when there is no traffic. Since the vast majority of networks use switches which effectively isolate the nodes and only switch together nodes when a frame is detected, 100BaseT link pulses would all be ignored by the switch and other nodes would not see them. This is why most copper 100Mbps Ethernet equipment is 100BaseTX compatible. 802.3z and 802.3ab each cover variations of the GigEther or Gigabit Ethernet technologies that are slowly emerging today also.
The 802.3z subcommittee added 1000BaseLX which is a Gigether that uses either single mode or multimode fiber optic fiber based equipment. The single mode supports maximum cables of 5000M and the multimode supports maximum cables of 550M. The 1000BaseSX also specified under 802.3z supports a variation of fiber optic technology using only 50 micron multimode fiber cables with a maximum length of 550M. 1000BaseCX uses STP but is limited to 25M. The 802.3ab subcommittee lays out the specification for Gigether that is similar to the 10BaseT and the 100BaseT predecessors and is called 1000BaseT. This technology supports the use of CAT5 for up to 100M. 802.3ab accomplishes this by using all four pairs simultaneously with each pair transmitting at 250Mbps. This solution is similar to the 100BaseT4 VG-AnyLAN technique of using three pairs of the CAT3 cable at 33Mbps each to achieve 100Mbps throughput although it is half duplex and of course this is exactly the same situation that 1000BaseT encounters: it is half duplex not full duplex.
To round out the 802 subcommittees then, 802.1 deals with Internetworking. This specification lays the groundwork for manufacturers to develop equipment designed specifically for attaching one entire complete and working network to another especially if they are using different low level technologies including different physical signaling, and logical framing. The 802.1d paragraph describes spanning tree bridges that will prevent infinite loops if more than one bridge can forward frames from one segment of a large network to another. 802.1q describes the standards for developing devices that can create VLANs. This is usually done by switches which are nothing more than multiport bridges so here again is a technology that pertains to bridging.
The IEEE 802.4 lays out the specifications for a totally obsolete technology called a Token Bus. In this form of LAN, all systems were attached to a bus like 10Base5 or 10Base2, but instead of using CSMA/CD like Ethernet, they used Token Passing for the MAC sublayer like IBM Token Ring. IBM Token Ring is fully laid out under IEEE 802.5 and is considered deprecated. IBM is slowly bringing many of its old technologies to the ends of their service lives meaning that they will no longer even have downloads available at their website. The three major contributions of the '80s are nearing this end of service life: PS/2 computers, OS/2 operating systems, IBM Token Ring networking.
IEEE 802.6 maps to Metropolitan Area Networking technologies. These will rarely be dealt with directly by the PC technician and the ComptTIA Network+ will not test on this section. IEEE 802.7 is the Broadband Technical Advisory Group. Another set of technologies that are not seen much at the PC level and again falls beyond the scope of the CompTIA Network+ and A+ examinations. The IEEE 802.8 Fiber-Optic Technical Advisory Group was going to develop a fiber optic lan technology based on the existing FDDI technologies. This appears to have been abandoned and the CompTIA will not ask about this section of the 802 standards either. The IEEE 802.9 specifications deal with Integrated Voice and Data networks that transmit voice and digital data over common twisted pair cabling installations as well as over ISDN lines. The CompTIA will not test the PC technician on this. 802.10 develops Standards for Interoperability between LANs using Security: SILS. This includes procedures as well as implementation and includes how networks should interface when they are using different security technologies. Again this falls beyond the scope of the PC technician.
802.11 is a rapidly growing section concerning Wireless networking. It is broken into four major discrete subcommittees: 802.11 "Original", 802.11a, 802.11b and 802.11g. 802.11 original, b and g all use the 2.4Ghz microwave band. While the original was the first equipment on the market, this equipment was not always reliably compliant with the standards which were still being developed and improved. b was the first fully functional standard to which manufacturers adhered with excellent interoperability results. a uses the higher absorbsion spectrum of the 5Ghz radio frequency band and is much shorter range and a much higher raw data transfer rate but also completely noncompatible with the predecessors and not yet approved in Europe and possibly elsewhere. g was designed specifically to use the band and transmission techniques of b so it is fully backwards compatible while offering the ability of two 802.11g devices to be able to fall forward to a faster data transfer rate than the 802.11b systems can achieve.
The IEEE 802.12 committee developed another set of LAN rules for medium contention called the "Demand Priority Access Method." This is the foundation specification document for 100BaseT4 VG-AnyLAN, a fairly rare and long obsolete technology that might still be in extremely limited use.
Here is a review table:
|802.1ab||Link layer discovery between Ethernet devices such as switches that exchange their MIB - Management Information Base, information|
|802.1ad||Amendment to the 802.1q that provides multiple instances of MAC services across a bridged LAN with minimal manual configuration (VLAN autoconfiguration/autodetection)|
|802.1d||Spanning Tree Algorithm for LAN Bridges (Bridges can detect each other and choose how to forward packets to avoid bridging loops)|
|802.1p||Switch packet prioritization and GARP - Generic Attributes Registration Protocol for VLAN's (superior throughput between members of tagged VLAN's)|
|802.1q||Standards for VLAN Technologies. Specification for tagged VLAN's including new "tagged VLAN Ethernet frame" adding 4 bytes to the original "raw" Ethernet frame header. 12 bits serve as the VLAN ID# allowing for up to 4096 separate VLAN's on the network.|
|802.1x||Network access control used in Wi-fi, also defines EAPOL - EAP Over LAN, for Ethernet, controls access to the network at the MAC level.|
|802.2||Ethernet LLC Sublayer|
|802.3||Ethernet MAC Sublayer (CSMA/CD) and Physical Layers|
|802.3z||Gigabit Ethernet: 1000BaseLX and 1000BaseSX (fiber optic based), 1000BaseCX (copper based but not compatible with existing 100BaseTX technologies)|
|802.3ab||Gigabit Ethernet: 1000BaseTX|
|802.3ad||Link Aggregation, allows two Ethernet nodes to communicate through more than one cable simultaneously|
|802.3ae||10 Gigabit Ethernet (fiber optic only)|
|802.3af||Power over Ethernet, provides 48V over 2 or 4 pair UTP|
|802.3ah||Ethernet over the First Mile: EFMC (copper) based on SHDSL, defines EFMF (fiber) also|
|802.3ak||Copper wire 10 Gigabit Ethernet, short distances using twinax cables|
|802.4||Token Bus (Abandoned)|
|802.5||IBM Token Ring|
|802.6||Metropolitan Area Networks|
|802.7||Broadband Technical Advisory Group|
|802.8||Fiber Optic Technical Advisory Group (Abandoned)|
|802.9||Integrated Voice and Data Networks|
|802.10||Standards for Interoperability between LANs using Security: SILS|
|802.11||Standards for Wireless LAN Technology - Wi-Fi|
|802.11b||Wireless LAN Technology: 11Mbps at 2.4Ghz|
|802.11a||Wireless LAN Technology: 54Mbps at 5Ghz|
|802.11g||Backwards compatible to 802.11b with higher data rates|
|802.12||Demand Priority MAC Sublayer Networks - 100BaseT4 (VG-AnyLAN)|
|802.16||Metropolitan Area Wireless Networking - WiMax|
Which IEEE specification would specify the usage of no more than 500M of RG-8?
Which IEEE specification specifies the usage of a form of Ethernet using STP cabling?
Which IEEE specification(s) might cover a form of Ethernet using SC or ST connectors?
Which IEEE specification attempted to develop a standard for FDDI network technologies?
Which IEEE specification describes Token ring networks?
Which IEEE specification describes Gigabit Ethernet with the same cables and ranges between nodes as its predecessors?
Which IEEE specification describes the protocol for intelligent bridges?
Which IEEE specification describes the technologies for use in VLANs?
Which IEEE specification describes the structure of Ethernet frames?
Which IEEE specification describes the rules of contention for Ethernet nodes?
Which IEEE specification describes 100BaseT4 networks?
Which IEEE specification describes wireless networking using the 5Ghz band?
Which IEEE specification describes a wireless technology purposely designed to be backwards compatible to its predecessor?
Which IEEE specification describes a wireless technology using the 2.4Ghz band and up to 11Mbps data transfer rates?
Which IEEE specification describes an Ethernet technology that uses 5000M single mode fiber optic cable? What is the speed of this network technology?
Which IEEE specification describes an Ethernet technology that is physically incapable of duplex operation? Explain why. This is similar to what other type of network? That type of network is described under which IEEE specification?
List all of the IEEE specifications that describe networks that use token passing at their MAC layer.
List all of the IEEE specifications that describe networks that use CSMA/CD at their MAC layer.
Which IEEE specification describe bridge functionality?
List all of the IEEE specifications that describe physical star topology networks.
List all of the IEEE specifications that describe physical bus topology networks.
List all of the IEEE specifications that describe fiber optic Ethernet technologies.
Copyrightę2000-2007 Brian Robinson ALL RIGHTS RESERVED