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Medium Access Control Sublayer Medium Access Control Sublayer

Static Channel Allocation Static Channel Allocation

Dynamic Channel Allocation : Dynamic Channel Allocation :

Basic Assumptions Basic Assumptions

Basic assumptions contd… Basic assumptions contd…

Multiple Access Protocols Multiple Access Protocols

PURE ALOHA PURE ALOHA

Pure ALOHA contd… Pure ALOHA contd…

Pure ALOHA contd… Pure ALOHA contd…

Pure ALOHA contd… Pure ALOHA contd…

Pure ALOHA contd… Pure ALOHA contd…

Pure ALOHA contd… Pure ALOHA contd…

Contd. . Contd. .

Pure ALOHA contd… Pure ALOHA contd…

Slotted ALOHA Slotted ALOHA

Slotted ALOHA contd… Slotted ALOHA contd…

Slotted ALOHA Slotted ALOHA

CSMA : Carrier Sense Multiple Access Protocols CSMA : Carrier Sense Multiple Access Protocols

CSMA contd… CSMA contd…

1 -persistent contd. . 1 -persistent contd. .

Nonpersistent CSMA Nonpersistent CSMA

p- persistent CSMA p- persistent CSMA

Comparison Comparison

CSMA/CD: CSMA with Collision Detection CSMA/CD: CSMA with Collision Detection

CSMA with Collision Detection CSMA with Collision Detection

What should be the size of the contention interval? What should be the size of the contention interval?

CSMA/CD contd. . CSMA/CD contd. .

CSMA/CD CSMA/CD

Collision-Free Protocols Collision-Free Protocols

Collision-Free Protocols Collision-Free Protocols

Performance Performance

Collision-Free Protocols (2) Collision-Free Protocols (2)

Channel efficiency Channel efficiency

A Variation of Binary countdown – by Mok and Ward(1979) A Variation of Binary countdown – by Mok and Ward(1979)

Revisit p-persistent Protocol Revisit p-persistent Protocol

when k is small I. e. limited contention when k is small I. e. limited contention

Performance Comparison Performance Comparison

Limited- Contention Protocols Limited- Contention Protocols

Assign stations to groups dynamically Assign stations to groups dynamically

Adaptive Tree Walk Protocol Adaptive Tree Walk Protocol

How far down the tree the search must begin? How far down the tree the search must begin?

WDMA: Wavelength Division Multiple access : MAC sub-layer in optical networks WDMA: Wavelength Division Multiple access : MAC sub-layer in optical networks

Contd. . Contd. .

More topics for presentation(1 person each) More topics for presentation(1 person each)

3 types of traffic 3 types of traffic

Dynamic WDMA contd… Dynamic WDMA contd…

Variable Data Rate CO traffic Variable Data Rate CO traffic

Constant Data Rate COO Constant Data Rate COO

Data-gram traffic Data-gram traffic

MAC Sub-layer in Wireless LANs MAC Sub-layer in Wireless LANs

Wireless LANs Wireless LANs

WLANs contd. . WLANs contd. .

Can we use CSMA? Can we use CSMA?

Wireless LAN Protocols Wireless LAN Protocols

Problem near the receiver Problem near the receiver

Simultaneous transmissions are possible in WLANs Simultaneous transmissions are possible in WLANs

Wireless LAN Protocols (2) Wireless LAN Protocols (2)

MACA : Multiple Access with Collision Avoidance MACA : Multiple Access with Collision Avoidance

Effect of MACA on other stations Effect of MACA on other stations

Collisions may still occur Collisions may still occur

Data Link Layer Switching Data Link Layer Switching

Data Link Layer Switching Data Link Layer Switching

Why LAN of LANs? Why LAN of LANs?

Bridges from 802. x to 802. y Bridges from 802. x to 802. y

Difficulties in bridging 802. x with 802. y Difficulties in bridging 802. x with 802. y

Bridges from 802. x to 802. y (2) Bridges from 802. x to 802. y (2)

Local Internetworking Local Internetworking

Routing in Interconnected LANs Routing in Interconnected LANs

Routing in Interconnected LANs Routing in Interconnected LANs

Spanning Tree Bridges (2) Spanning Tree Bridges (2)

Remote Bridges Remote Bridges

Repeaters and Hubs : Physical Layer Repeaters and Hubs : Physical Layer

Switches and Bridges : DLL Switches and Bridges : DLL

Virtual LANs (2) Virtual LANs (2)

The IEEE 802. 1 Q Standard The IEEE 802. 1 Q Standard

The IEEE 802. 1 Q Standard (2) The IEEE 802. 1 Q Standard (2)

Summary Summary

MACAW (MACA for wireless) by Bhargavan et al MACAW (MACA for wireless) by Bhargavan et al

I Acknowledge I Acknowledge