Osi data link layer
Download
1 / 63

OSI Data Link Layer - PowerPoint PPT Presentation


  • 79 Views
  • Uploaded on

OSI Data Link Layer. Network Fundamentals – Chapter 7. Objectives. Explain the role of Data Link layer protocols in data transmission. Describe how the Data Link layer prepares data for transmission on network media. Describe the different types of media access control methods.

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about ' OSI Data Link Layer' - gefen


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
Osi data link layer

OSI Data Link Layer

Network Fundamentals – Chapter 7


Objectives
Objectives

  • Explain the role of Data Link layer protocols in data transmission.

  • Describe how the Data Link layer prepares data for transmission on network media.

  • Describe the different types of media access control methods.

  • Identify several common logical network topologies and describe how the logical topology determines the media access control method for that network.

  • Explain the purpose of encapsulating packets into frames to facilitate media access.

  • Describe the Layer 2 frame structure and identify generic fields.

  • Explain the role of key frame header and trailer fields including addressing, QoS, type of protocol and Frame Check Sequence.


Context index
Context Index

  • 7.1 Data Link Layer – Accessing the Media

  • 7.2 Media Access Control Techniques

  • 7.3 Media Access Control Addressing and Framing Data

  • 7.4 Putting it All Together

  • 7.5 Labs and Activities


7 1 data link layer accessing the media

7.1 Data Link Layer – Accessing the Media


7 1 1 data link layer supporting connecting to upper layer services
7.1.1 Data Link Layer – Supporting & Connecting to Upper Layer Services

  • The Data Link layer performs two basic services:

    -Allows the upper layers to access the media using techniques such as framing

    -Controls how data is placed onto the media and is received from the media using techniques such as media access control and error detection



7 1 1 data link layer supporting connecting to upper layer services2
7.1.1 Data Link Layer – Supporting & Connecting to Upper Layer Services

  • Numerous Data Link layer protocols are being used over various types of LANs and WANs.


7 1 2 data link layer controlling transfer across local media
7.1.2 Data Link Layer – Controlling Transfer across Local Media

  • Layer 2 protocols specify the encapsulation of a packet into a frame .


7 1 3 data link layer creating a frame
7.1.3 Data Link Layer – Creating a Frame Media

  • Data Link layer frame includes:


7 1 3 data link layer creating a frame1
7.1.3 Data Link Layer – Creating a Frame Media

  • The role the Data Link layer plays in linking the software and hardware layers


7 1 4 data link layer connecting upper layer services to the media
7.1.4 Data Link Layer – Connecting Upper Layer Services to the Media

  • Data Link layer is often divided into two sub-layers:

    -Logical Link Control

    -Media Access Control


7 1 5 data link layer standards
7.1.5 Data Link Layer – Standards the Media

  • Standards for the Data Link layer



7 2 1 placing data on the media
7.2.1 Placing Data on the Media the Media

  • Explain the necessity for controlling access to the media


7 2 2 media access control for shared media
7.2.2 Media Access Control for Shared Media the Media

  • There are two basic media access control methods for shared media:

    -Controlled - Each node has its own time to use the medium

    -Contention-based- All nodes compete for the use of the medium


7 2 2 media access control for shared media1
7.2.2 Media Access Control for Shared Media the Media

  • There are two basic media access control methods for shared media:

    -Controlled - Each node has its own time to use the medium

    -Contention-based- All nodes compete for the use of the medium


7 2 2 media access control for shared media2
7.2.2 Media Access Control for Shared Media the Media

  • There are two basic media access control methods for shared media:

    -Controlled - Each node has its own time to use the medium

    -Contention-based- All nodes compete for the use of the medium


7 2 3 media access control for non shared media
7.2.3 Media Access Control for Non-Shared Media the Media

  • Define Full Duplex and Half Duplex as it relates to Media Access Control for non-shared media


7 2 3 media access control for non shared media1
7.2.3 Media Access Control for Non-Shared Media the Media

  • Define Full Duplex and Half Duplex as it relates to Media Access Control for non-shared media


7 2 3 media access control for non shared media2
7.2.3 Media Access Control for Non-Shared Media the Media

  • Define Full Duplex and Half Duplex as it relates to Media Access Control for non-shared media


7 2 4 logical topology vs physical topology
7.2.4 Logical Topology vs Physical Topology the Media

  • The representation of how the media is used to interconnect the devices is the physical topology.

  • A logical topology is the way a network transfers frames from one node to the next.

  • Topologies used in networks

    are:

    -Point-to-Point

    -Multi-Access

    -Ring


7 2 5 point to point topology
7.2.5 Point-to-Point Topology the Media

  • A point-to-point topology connects two nodes directly together.


7 2 5 point to point topology1
7.2.5 Point-to-Point Topology the Media

  • A virtual circuit is a logical connection created within a network between two network devices.


7 2 5 point to point topology2
7.2.5 Point-to-Point Topology the Media

  • A virtual circuit is a logical connection created within a network between two network devices.


7 2 6 multi access topology
7.2.6 Multi-Access Topology the Media

  • Data from only one node can be placed on the medium at any one time.

  • Every node sees all the frames that are on the medium, but only the node to which the frame is addressed processes the contents of the frame.

  • A Data Link media access control method is required to regulate the transmission of data.

  • The media access control methods are typically CSMA/CD or CSMA/CA.


7 2 6 multi access topology1
7.2.6 Multi-Access Topology the Media

  • How nodes access the media in a multi-access topology


7 2 7 ring topology
7.2.7 Ring Topology the Media

  • In a logical ring topology, each node in turn receives a frame. If the frame is not addressed to the node, the node passes the frame to the next node.

  • If there is no data being transmitted, a signal (known as a token) may be placed on the media and a node can only place a data frame on the media when it has the token.


7 2 7 ring topology1
7.2.7 Ring Topology the Media

  • How nodes access the media in a logical ring topology


7 3 media access control addressing and framing data

7.3 Media Access Control Addressing the Media and Framing Data


7 3 1 data link layer protocols the frame
7.3.1 Data Link Layer Protocols – The Frame the Media

  • The structure of the frame and the fields contained in the header and trailer vary according to the protocol.


7 3 2 framing role of the header
7.3.2 Framing – Role of the Header the Media

  • The role of the frame header in the Data Link layer


7 3 3 addressing where the frame goes
7.3.3 Addressing – Where the Frame Goes the Media

  • Data Link layer addressing is contained within the frame header and specifies the frame destination node on the local network.

  • If the device is moved to another network or subnet, physical addresses will still function with the same Layer 2 physical address.

  • The intermediate device - a router - will decapsulate the original frame, create a new frame for the packet.


7 3 3 addressing where the frame goes1
7.3.3 Addressing – Where the Frame Goes the Media

  • Addressing Requirements


7 3 4 framing role of the trailer
7.3.4 Framing – Role of the Trailer the Media

  • The role of the frame trailer in the Data Link layer


7 3 5 data link layer protocol the frame
7.3.5 Data Link Layer Protocol – The Frame the Media

  • Given the wide range of physical media used in networking, there are a correspondingly high number of Layer 2 protocols in use.

802.11 Wireless

Frame

HDLC

802.11 Wireless

Frame

Frame Relay

PPP frame

Ethernet Frame


7 3 5 data link layer protocol the frame1
7.3.5 Data Link Layer Protocol – The Frame the Media

  • Ethernet Protocol for LANs


7 3 5 data link layer protocol the frame2
7.3.5 Data Link Layer Protocol – The Frame the Media

  • Point-to-point Protocol for WANs


7 3 5 data link layer protocol the frame3
7.3.5 Data Link Layer Protocol – The Frame the Media

  • Wireless Protocol for LANs

More Data field -Set to 1 to indicate to a node in power-save mode that more frames are buffered for that node

Power Management field -Set to 1 to indicate that a node will be in power-save mode

Retry field -Set to 1 if the frame is a retransmission of an earlier frame

From DS field -Set to 1 in data frames exiting the distribution system

More Fragments field -Set to 1 for frames that have another fragment

Transmitter Address (TA) field -MAC address that identifies the wireless device that transmitted the frame

To DS field -Set to 1 in data frames destined for the distribution system (devices in the wireless structure)

Duration/ID field -Depending on the type of frame, represents either the time, in microseconds, required to transmit the frame or an association identity (AID) for the station that transmitted the frame

Sequence Number field -Indicates the sequence number assigned to the frame; retransmitted frames are identified by duplicate sequence numbers

Fragment Number field -Indicates the number for each fragment of a frame

Order field -Set to 1 in a data type frame that uses Strictly Ordered service class (does not need reordering)

FCS field -Contains a 32-bit cyclic redundancy check (CRC) of the frame

Destination Address (DA) field -MAC address of the final destination node in the network

Source Address (SA) field -MAC address of the node the initiated the frame

Frame Body field -Contains the information being transported; for data frames, typically an IP packet

Type and Subtype fields –

Identifies one of three functions and sub functions of the frame: control, data, and management

Receiver Address (RA) field -MAC address that identifies the wireless device that is the immediate recipient of the frame

Wired Equivalent Privacy (WEP) field -Set to 1 if the frame contains WEP encrypted information for security

Protocol Version field - Version of 802.11 frame in use



7 4 1 follow data through an internetwork
7.4.1 Follow Data Through an Internetwork the Media

  • A simple data transfer between two hosts across an internetwork.


7 4 1 follow data through an internetwork1
7.4.1 Follow Data Through an Internetwork the Media

  • A simple data transfer between two hosts across an internetwork.


7 4 1 follow data through an internetwork2
7.4.1 Follow Data Through an Internetwork the Media

  • A simple data transfer between two hosts across an internetwork.


7 4 1 follow data through an internetwork3
7.4.1 Follow Data Through an Internetwork the Media

  • A simple data transfer between two hosts across an internetwork.


7 4 1 follow data through an internetwork4
7.4.1 Follow Data Through an Internetwork the Media

  • A simple data transfer between two hosts across an internetwork.


7 4 1 follow data through an internetwork5
7.4.1 Follow Data Through an Internetwork the Media

  • A simple data transfer between two hosts across an internetwork.


7 4 1 follow data through an internetwork6
7.4.1 Follow Data Through an Internetwork the Media

  • A simple data transfer between two hosts across an internetwork.


7 4 1 follow data through an internetwork7
7.4.1 Follow Data Through an Internetwork the Media

  • A simple data transfer between two hosts across an internetwork.


7 4 1 follow data through an internetwork8
7.4.1 Follow Data Through an Internetwork the Media

  • A simple data transfer between two hosts across an internetwork.


7 4 1 follow data through an internetwork9
7.4.1 Follow Data Through an Internetwork the Media

  • A simple data transfer between two hosts across an internetwork.


7 4 1 follow data through an internetwork10
7.4.1 Follow Data Through an Internetwork the Media

  • A simple data transfer between two hosts across an internetwork.


7 4 1 follow data through an internetwork11
7.4.1 Follow Data Through an Internetwork the Media

  • A simple data transfer between two hosts across an internetwork.


7 4 1 follow data through an internetwork12
7.4.1 Follow Data Through an Internetwork the Media

  • A simple data transfer between two hosts across an internetwork.


7 4 1 follow data through an internetwork13
7.4.1 Follow Data Through an Internetwork the Media

  • A simple data transfer between two hosts across an internetwork.


7 4 1 follow data through an internetwork14
7.4.1 Follow Data Through an Internetwork the Media

  • A simple data transfer between two hosts across an internetwork.


7 4 1 follow data through an internetwork15
7.4.1 Follow Data Through an Internetwork the Media

  • A simple data transfer between two hosts across an internetwork.


7 4 1 follow data through an internetwork16
7.4.1 Follow Data Through an Internetwork the Media

  • A simple data transfer between two hosts across an internetwork.


7 4 1 follow data through an internetwork17
7.4.1 Follow Data Through an Internetwork the Media

  • A simple data transfer between two hosts across an internetwork.


7 4 1 follow data through an internetwork18
7.4.1 Follow Data Through an Internetwork the Media

  • A simple data transfer between two hosts across an internetwork.


7 4 1 follow data through an internetwork19
7.4.1 Follow Data Through an Internetwork the Media

  • A simple data transfer between two hosts across an internetwork.


7 4 1 follow data through an internetwork20
7.4.1 Follow Data Through an Internetwork the Media

  • A simple data transfer between two hosts across an internetwork.


7 4 1 follow data through an internetwork21
7.4.1 Follow Data Through an Internetwork the Media

  • A simple data transfer between two hosts across an internetwork.


Summary
Summary the Media


ad