IEEE 802.3

The first version was an attempt to standardize although there was an ethernet header field is defined differently, then there have been successive extensions to the standard extensions covering speed (Fast Ethernet, Gigabit Ethernet and 10 Gigabit) networks virtual hubs, switches and various types of media, both fiber optic and copper cables (both coaxial and twisted pair).

The standards of this group do not necessarily reflect what is used in practice, but unlike other groups this is often closer to reality.

IEEE 802.1D

802.1D is the IEEE standard for MAC bridges (bridges MAC), which includes bridging (packet forwarding technique used by switches), the protocol Spaning Tree and operation of 802.11 networks, among others.

It also prevents loops that are formed when switches or bridges are interconnected through various rutas.el algorithm by exchanging BPDU messages with other switches to detect loops, and then removes the loop by the bridge closure selected interfaces. This algorithm ensures that there is one and only one active path between two network devices.

VLANs (virtual networks) are not part of 802.1D, but IEEE_802.1Q.

History:

• 1990 - Original Issue (802.1D-1990), based on the ISO / IEC 10038.
• 1998 - Revised version (802.1D-1998), incorporating extensions IEEE_802.1p, P802.12e, 802.1jy 802.6k.
• 2004 - Revised version (802.1D-2004), incorporating 802.1ty 802.1w extensions, which was published separately in 2001, eliminated the original protocol Spanning tree and instead incorporated the Rapid Spanning Tree Protocol (RSTP) for 802.1w.

IEEE 802.1Q

The IEEE 802.1Q was a project of the Working Group 802 of the IEEE to develop a mechanism to allow multiple networks transparently share the same physical medium, without problems of interference between them (Trunking). It is also the name of the current standards set out in this project and used to define the encapsulation protocol used to implement this mechanism over Ethernet networks.

Frame format

802.1Q does not actually encapsulate the original frame but adds 4 bytes to the original Ethernet header. The EtherType field value is changed to 0 × 8100 to mark the change in the format of the plot.

Because the change of the frame header is changed, 802.1Q force a recalculation of the field "FCS".

Native VLAN

Point 9 of the standard defines the encapsulation protocol used to multiplex VLANs across a single link, and introduces the concept of native VLAN. Frames belonging to the native VLAN is not tagged with VLAN ID when sending the trunk. And on the other hand, if a frame arrives port untagged, the plot is considered to belong to the native VLAN on the port. This mode was implemented funcionamiennto to ensure interoperability with older devices that do not understand 802.1Q.

The native VLAN is the VLAN to which it belonged on a switch port before being configured as a trunk. You can only have one native VLAN per port.

To establish a trunking 802.1qa both sides should have the same native VLAN encapsulation because still not been established and the two switches should discuss a link without encapsulation (using the native VLAN) to agree on these parameters. At Cisco Systems equipment default the native VLAN is VLAN 1. In addition to VLAN 1 data, it sends information about PAgP, CDP, VTP.

During the design is recommended

• The native VLAN should not be the management.
• Change the native VLAN 1 to any other as a security measure.
• All switches in the same native VLAN.
• Users and servers in their respective VLANs.
• Traffic between switches must be the only one not encapsulated in trunk links. Other traffic, including the management VLAN must be encapsulated by the trunks. If we can connect an encapsulating anyone who does not speak 802.1q equipment (switches and hubs) and will operate without our control.

IEEE 802.1p

IEEE 802.1p is a standard that provides traffic prioritization and dynamic multicast filtering. Essentially, it provides a mechanism for implematar Quality of Service (QoS) at the MAC (Media Access Control).

There are 8 different kinds of services, expressed by 3 bits of user priority field (user_priority) IEEE_802.1Q header added to the plot, assigning each packet a priority level between 0 and 7. Although a prioritization method widely used in LAN environments, has several disadvantages, such as the requirement for an additional 4-byte tag (defined in IEEE 802.1Q standard). In addition it can only be supported on a LAN, as 802.1Q tags are removed when the packets pass through a router.

It is defined as how to handle the traffic that is assigned to a particular class or priority, leaving freedom to the implementations. IEEE, however, has made extensive recommendations.

802.1p is integrated into IEEE_802.1D and 802.1Q standards.

IEEE 802.1X

The IEEE 802.1X is an IEEE standard for network admission control based on ports. It is part of the protocol IEEE 802 (IEEE 802.1). Enables authentication of devices connected to a LAN port, establishing a point to point connection or preventing access to that port if authentication fails. It is used in some wireless access points closed and is based on Extensible Authentication Protocol (EAP-RFC 2284). The RFC 2284 has been deprecated in favor of RFC 3748.

802.1X is available in certain network switches and can be configured to authenticate nodes that are equipped with supplicant software. This eliminates unauthorized access to network at the level of the data link layer.

Some vendors are implementing 802.1X wireless access points that can be used in certain situations in which the access point needs to be operated as a closed access point, correcting security flaws of WEP. This authentication is usually performed by a third party, such as a RADIUS server. This allows client authentication only or, more appropriately, strong mutual authentication using protocols such as EAP-TLS.

IEEE 802.11

The IEEE 802.11 or Wi-Fi IEEE defines the use of the two lower levels of the OSI architecture (physical and link layers of data), specifying its rules of operation in a WLAN. The protocols define the technology branch 802.x local area networks and metropolitan area networks (MAN).

Today most products are of the specification by the g, but has already completed the first draft of the 802.11n standard that raises the theoretical limit to 600 Mbps There are already several products that meet a first draft N standard with up to 300 Mbps (80-100 stable).

The 802.11n standard uses two bands, 2.4 GHz and 5 GHz networks working in 802.11b and 802.11g standards can suffer interference from microwave ovens, cordless phones and other devices that use the same band 2 , 4 Ghz.

However, the mass of 802.11n technology, which seems to be on their way, will also provide a progressive saturation of the spectrum of "free use" in the 5 GHz band.

In short, the 5.4 GHz-based services, such as the "Wimax, unlicensed" or Pre-Wimax, could be severely affected, especially in cities where it is most likely mass of wireless users.

This has happened between the years 2004-2005, also called "pre-wimax" working in 2.4 GHz frequency and caused 100% of the installed links would see in cities severely affected by the interference of wifi.

It all started when ADSL operators, begin to give wifi router 2.4 Ghz (802.11bg), this mass of users in the 2.4 GHz band operation resulted in the inability of the links on a certain distance (greater than 100 meters), due to the saturation spectrum.

It could be a strategy of the operators themselves, to eliminate competition in services that do not have licenses to use radio spectrum, but could also undermine other initiatives using free bands as a means of communication for urban networking.

Legacy IEEE 802.11

The original version of IEEE 802.11 standard published in 1997 specifies two theoretical data rates of 1 and 2 megabits per second (Mbit / s) signals that are transmitted by infrared (IR). IR remains a part of the standard, although there are no implementations available.

The original standard also defines the CSMA / CA (Multiple Carrier Detect access by avoiding collisions) as the access method. An important part of the theoretical transmission speed used in this encoding needs to improve transmission quality under different environmental conditions, which resulted in difficulties in interoperability between equipment of different brands. These and other weaknesses were corrected in the 802.11b standard, which was the first of this family to achieve broad acceptance among consumers.

IEEE 802.11a

In 1997, the IEEE (Institute of Electrical and Electronics Engineers) 802.11 standard created with transmission speeds of 2Mbps.

In 1999, the IEEE approved both standards: 802.11a and 802.11b.

In 2001 he made his appearance on the market 802.11a products.

802.11a revision to the original standard was ratified in 1999. The 802.11a standard uses the same basic set of protocols that the original standard, operates in the 5 GHz band and uses orthogonal subcarriers 52 frequency-division multiplexing (OFDM) with a top speed of 108 Mbit / s, making it a practical standard for wireless networks with actual speeds of about 20 Mbit / s. The data rate is reduced to 48, 36, 24, 18, 12, 9 and 6 Mbit / s if necessary. 802.11a has 12 non-overlapping channels, 8 for wireless network connections and 4 for point to point. Not interoperable with 802.11b equipment, unless equipment is available that implement both standards.

Since the 2.4 GHz band has much use (it is the same band used by cordless phones and microwave ovens, among other devices), using the 5 GHz band is an advantage of the 802.11a standard, since it have less interference. However, the use of this band also has its disadvantages, since it restricts the use of 802.11a equipment online only points of view, which is necessary to install more access points; This also means teams that work with this standard can not penetrate as far as the 802.11b standard because its waves are more easily absorbed.

802.11b IEEE

The review original 802.11b standard was ratified in 1999. 802.11b has a maximum transmission speed of 11 Mbit / s using the same access method CSMA / CA defined in the original standard. The 802.11b standard operates in the 2.4 GHz band due to the space occupied by the encoding of CSMA / CA, in practice, the transmission speed of this standard is approximately 5.9 Mbit / s over TCP and 7.1 Mbit / s over UDP.

Although it also uses a spread spectrum technique based on DSSS, 802.11b extension really introduces CCK (Complementary Code Keying) to reach speeds of 5.5 and 11 Mbps (bit physical). The standard also supports the use of PBCC (Packet Binary Convolutional Coding) as optional. 802.11b devices must maintain backward compatibility with DSSS equipment specified in the original IEEE 802.11 standard with bit rates of 1 and 2 Mbps

IEEE 802.11c

It is less used than the first two, but implementing this protocol reflects. The protocol 'c' is used for communication of two different networks or different types and can be either two separate buildings connected with each other, and connect two networks of different types via a wireless connection. The protocol 'c' is used daily, due to the cost of the long distance fiber optic installation, although more reliable, it is more costly both in monetary instruments as at installation time.

IEEE 802.11d

It complements the 802.11 standard is designed to enable international use of the local 802.11 networks. Allows multiple devices to exchange information in the frequency ranges as allowed in the country of origin of the device.

IEEE 802.11e

With the 802.11 standard, IEEE 802.11 technology supports real-time traffic in all types of environments and situations. Real-time applications are now a reality for guarantees Quality of Service (QoS) provided by the 802.11e. The aim of the new 802.11e standard is to introduce new mechanisms at the MAC layer to support services that require QoS guarantees. To achieve its objective IEEE 802.11e introduces a new element called Hybrid Coordination Function (HCF) with two types of access:

• (EDCA) and Enhanced Distributed Channel Access
• (HCCA) Controlled Access.

IEEE 802.11f

It is a recommendation for access point vendors that allows products to be more compatible. Use the IAPP protocol that allows a roaming user clearly changed an access point to another while moving no matter what brands of access points used in the network infrastructure. Also this property is known simply as roaming.

IEEE 802.11g

In June 2003, endorsed a third modulation standard, 802.11g. That is the evolution of the 802.11b standard, it uses the 2.4 GHz band (like 802.11b) but operates at a theoretical maximum speed of 54 Mbit / s, which on average is 22.0 Mbit / s real speed transfer, similar to the 802.11a standard. It is compatible with the standard by using the same frequencies. Much of the standard design process it took to reconcile the two standards. However, the standard g networks under the presence of nodes under the standard b significantly reduces the transmission rate.

The teams working on the 802.11g standard hit the market very quickly, even before ratification was given approx. on June 20, 2003. This was due in part to build teams under the new standard could be adapted and designed for the standard b.

Currently sell equipment with this specification, with powers up to half a watt, which allows communication at up to 50 km with appropriate dishes. and i-MOX technology will reach several kilometers.

IEEE 802.11h

The 802.11h specification is an amendment to the 802.11 standard for WLANs developed by working group 11 of the standards committee LAN / MAN of the IEEE (IEEE 802) and which was released in October 2003. 802.11h tries to resolve problems arising from the coexistence of 802.11 networks with radar and satellite systems

The development of 802.11h is about recommendations made by ITU who were motivated mainly because of the requirements that the European Radiocommunications Office (ERO) thought fit to minimize the impact of opening the 5 GHz band, generally used for military systems, ISM applications (ECC / DEC / (04) 08).

In order to comply with these requirements, 802.11h 802.11a networks provides the ability to manage both the frequency dynamically, such as transmission power.

Dynamic Frequency Selection and Transmit Power Control

DFS (Dynamic Frequency Selection) is a required feature for WLANs operating in the 5GHz band to avoid co-channel interference with radar systems and to ensure uniform use of the available channels.

TPC (Transmitter Power Control) is a required feature for WLANs operating in the 5GHz band to ensure that they comply with the limitations that can be transmitted power for different channels in a given region, so as to minimize interference with systems Satellite.

IEEE 802.11i

It is aimed at breaking the current vulnerability in the security authentication protocols and encryption. The standard encompasses 802.1X, TKIP (Integra Key Protocol - Secure - Temporary) and AES (Advanced Encryption Standard). It is implemented in WPA2.

IEEE 802.11j

Japan is to regulate what the 802.11h is to European regulation.

IEEE 802.11k

Allows switches and wireless access points to calculate and assess the resources from wireless clients in a WLAN network, improving its management. It is designed to be implemented in software, to support the equipment needs to be updated only WLAN. And, of course, that the standard be effective, must be supported by both clients (WLAN cards and adapters) and infrastructure (access points and WLAN switches).

IEEE 802.11n

In January 2004, the IEEE announced the formation of a working group 802.11 (TGN) to develop a new revision of the 802.11 standard. The actual transmission speed could reach 600 Mbps (which means that the theoretical transmission speeds would be even higher) and should be up to 10 times faster than a network under 802.11a and 802.11g standards, and about 40 times faster than a network under the 802.11b standard. It is also hoped that the scope of network operation is greater with this new standard by MIMO Multiple Input - Multiple Output, which allows to use several channels at once to send and receive data by incorporating multiple antennas (3 ). There are alternative proposals that might be considered and it is expected that the standard should be completed by late 2006, is implemented by 2008. In early 2007 approved the second draft of the standard. Earlier devices had already developed the protocol and offered it as an unofficial standard (with the promise of updates to meet the standard when the final was implanted). Has suffered a series of delays and the last one leads to November 2009. Having approved the project in January 2009 and that 7.0 is on track to meet the dates señaladas.Status of Project IEEE 802.11n.

Unlike other versions of Wi-Fi, 802.11n can operate in two frequency bands: 2.4 GHz (the one used 802.11b and 802.11g) and 5 GHz (802.11a he uses). As a result, 802.11n is compatible with devices based on all previous versions of Wi-Fi. Furthermore, it is useful to work in the 5 GHz band, since it is less congested and 802.11n can achieve higher performance.

IEEE 802.11p

This standard operates in the frequency spectrum of 5.9 GHz, especially suitable for cars. It will be the basis of the Dedicated Short Range Communications (DSRC) in North America. DSRC technology will allow data exchange between vehicles and between vehicles and roadside infrastructure.

IEEE 802.11r

Also known as Fast Basic Service Set Transition, and its main feature is to allow the network to establish security protocols that identify a device on the new access point before you leave today and go to it. This feature, which seems obvious once stated, indispensable in a wireless data system, allows the transition between nodes takes less than 50 milliseconds. A time lapse of this magnitude is short enough to maintain communication via VoIP without any noticeable cuts.

IEEE 802.11s

Defines interoperability as manufacturers Mesh protocols (networks are those that mix the two topologies in wireless networks, Ad-hoc topology and topology infrastructure.). It is well known that there is no standard, and therefore each manufacturer has its own mechanisms for mesh generation.

IEEE 802.11w

Not yet concluded. TWG is working to improve access control layer of IEEE 802.11 medium to increase the security of authentication protocols and encryption. Wireless LANs send system information in unprotected frames, which makes them vulnerable. This standard may protect against network interruption caused by malicious systems that create disassociated requests that appear to be sent by valid equipment. It tries to extend the protection provided by the 802.11i standard beyond data to management frames, which are responsible for the main components of a network. These extensions will interfere with IEEE IEEE 802.11u 802.11re.

Proprietary protocol

IEEE 802.11g +

Today 802.11g Turbo mode, with a band of 2.4 GHz, achieves a transfer rate of 108 Mbps This is provided by the Atheros chipset.

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