1 / 18

Data Link Layer Lecture 17 Imran Ahmed University of Management & Technology

Data Link Layer Lecture 17 Imran Ahmed University of Management & Technology. Agenda. Introduction & services Error detection and correction Multiple access protocols LAN addresses and ARP Ethernet Hubs, bridges and switches. Multiple Access Links & Protocols. Two types of “links”:

wayne-figueroa
Télécharger la présentation

Data Link Layer Lecture 17 Imran Ahmed University of Management & Technology

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. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Data Link Layer Lecture 17 Imran Ahmed University of Management & Technology

  2. Agenda • Introduction & services • Error detection and correction • Multiple access protocols • LAN addresses and ARP • Ethernet • Hubs, bridges and switches

  3. Multiple Access Links & Protocols Two types of “links”: • Point-to-point:- • PPP for dial-up access • Point-to-point link between Ethernet switch and host • Broadcast:- • Traditional Ethernet • 802.11 wireless LAN

  4. Multiple Access Links & Protocols • MAC protocols: • Channel partitioning • Time division, Code division, Frequency division • Random partitioning • ALOHA, S-ALOHA, CSMA, CSMA/CD • Taking turns • Token passing

  5. Agenda • Introduction & services • Error detection and correction • Multiple access protocols • LAN addresses and ARP • Ethernet • Hubs, bridges and switches

  6. LAN Addresses & ARP • LAN (or MAC or physical or Ethernet) address: • It is used to get datagram from one interface to another physically-connected interface (same network). • 48 – bit MAC address; burned in the adapter ROM.

  7. LAN Addresses & ARP

  8. 223.1.1.2 223.1.2.2 223.1.2.1 223.1.3.2 223.1.3.1 223.1.3.27 IP Addressing • Starting at A, given IP datagram addressed to B: • Look up net. address of B, find B on same net. as A. • Link layer send datagram to B inside link-layer frame. 223.1.1.1 223.1.2.9 223.1.1.4 223.1.1.3

  9. Address Resolution Protocol • Each IP node on LAN has ARP table. • ARP Table: IP/MAC address mappings for some LAN nodes. <IP address; MAC address; TTL> • TTL: time after which address mapping will be forgotten (typically 20 min.)

  10. Agenda • Introduction & services • Error detection and correction • Multiple access protocols • LAN addresses and ARP • Ethernet • Hubs, bridges and switches

  11. Project 802 • In 1985, the Computer Society of the IEEE started a project, called Project 802, to set standards to enable intercommunication between equipment from a variety of manufacturers. • Project 802 uses the first two layers and, to a lesser extent, the network layer.

  12. OSI Model and Project 802

  13. Project 802 • The IEEE has subdivided the data link layer into two sub-layers: • Logical Link Control (LLC) • Medium Access Control (MAC)

  14. IEEE Project 802 • Each subdivision is identified by a number: • IEEE 802.1 (internetworking) • IEEE 802.2 (LLC) • IEEE 802.3 (CSMA/CD or Ethernet) • IEEE 802.4 (Token Bus) • IEEE 802.5 (Token Ring)

  15. Project 802

  16. IEEE Project 802 • IEEE 802.1: This section is devoted to internetworking issues in LANs and MANs. • Logical Link Control: IEEE 802.2 LLC is the upper sub-layer of the data link layer. It contains logical addresses, control information and data unit. • Media Access Control: MAC is the lower sub-layer of the data link layer. It contains the flag, flow and error control specification necessary to move information from one place to another.

  17. IEEE Project 802 Ethernet • IEEE 802.3 supports a LAN standard originally developed by Xerox and later extended by a joint venture between Digital Equipment Corporation, Intel Corporation and Xerox. This was called Ethernet. • IEEE 802.3 defines two categories: • Baseband • Broadband

More Related