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Protocollege

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Extensible Authentication Protocol. Extensible Authentication Protocol, or EAP, is an authentication framework frequently used in wireless networks and point-to-point connections.

Extensible Authentication Protocol

It is defined in RFC 3748, which made RFC 2284 obsolete, and was updated by RFC 5247. EAP is in wide use. For example, in IEEE 802.11 (WiFi) the WPA and WPA2 standards have adopted IEEE 802.1X with five EAP types as the official authentication mechanisms. Methods[edit] EAP is an authentication framework, not a specific authentication mechanism.[1] It provides some common functions and negotiation of authentication methods called EAP methods. The standard also describes the conditions under which the AAA key management requirements described in RFC 4962 can be satisfied. LEAP[edit] EAP-TLS[edit] EAP-Transport Layer Security (EAP-TLS), defined in RFC 5216, is an IETF open standard that uses the Transport Layer Security (TLS) protocol, and is well-supported among wireless vendors. EAP-MD5[edit] EAP-POTP[edit] Carrier sense multiple access with collision detection.

Simplified Algorithm of CSMA/CD CSMA/CD is a modification of pure carrier sense multiple access (CSMA).

Carrier sense multiple access with collision detection

CSMA/CD is used to improve CSMA performance by terminating transmission as soon as a collision is detected, thus shortening the time required before a retry can be attempted. Main procedure[edit] Is my frame ready for transmission? If yes, it goes on to the next point.Is medium idle? Collision detected procedure[edit] Continue transmission (with a jam signal instead of frame header/data/CRC) until minimum packet time is reached to ensure that all receivers detect the collision.Increment retransmission counter.Was the maximum number of transmission attempts reached?

This can be likened to what happens at a dinner party, where all the guests talk to each other through a common medium (the air). Jam signal[edit] The maximum jam-time is calculated as follows: The maximum allowed diameter of an Ethernet installation is limited to 232 bits. Applications[edit] See also[edit] Carrier sense multiple access with collision avoidance. It is particularly important for wireless networks, where the collision detection of the alternative CSMA/CD is unreliable due to the hidden node problem.

Carrier sense multiple access with collision avoidance

CSMA/CA is a protocol that operates in the Data Link Layer (Layer 2) of the OSI model.[3] Simplified Algorithm of CSMA/CA Details[edit] Collision avoidance is used to improve the performance of the CSMA method by attempting to divide the channel somewhat equally among all transmitting nodes within the collision domain. Carrier Sense: prior to transmitting, a node first listens to the shared medium (such as listening for wireless signals in a wireless network) to determine whether another node is transmitting or not. Request to Send/Clear to Send (RTS/CTS) may optionally be used at this point to mediate access to the shared medium. IEEE 802.11 RTS/CTS Exchange[edit] CSMA/CA can optionally be supplemented by the exchange of a Request to Send (RTS) packet sent by the sender S, and a Clear to Send (CTS) packet sent by the intended receiver R.