{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

Lecture5_Link Layer1 - I1070 T2000 Intro to Telecom The...

Info icon This preview shows pages 1–17. Sign up to view the full content.

View Full Document Right Arrow Icon
I1070 / T2000 Intro to Telecom The Data Link Layer Dr. Richard A. Thompson Telecommunications Program University of Pittsburgh
Image of page 1

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Learning Objectives Describe the role and functions of the link layer Describe some common link layer protocols Explain the rationale for flow and error control Understand ARQ systems Describe how stop and wait and sliding window flow control work Explain and characterize the performance differences between these two mechanisms
Image of page 2
Lecture outline Intro to Link layer & LANs Link layer functions Flow Control Error Control Example of HDLC Inherited slides: provided, but skipped in class Media Access Control - principles
Image of page 3

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
OSI Reference Model Not a very good model Usually merge Layers 5-7 2 missing layers: 0 & 8 Implies layers are independent Functions move around
Image of page 4
Functions Confusing issues Link LAN Multiplexing in HW or SW? Functions evolve to different layers
Image of page 5

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Link Between routers Which functions are needed? Internet R G/R G/R R G/R G/R uniform N N N Y Y N frag Y Y Y Y Y N mux Y N Y N N N
Image of page 6
LAN No internal IP Which functions are needed? Local Area Network H H G/R N Y Y Y Y Y H H H H Internet
Image of page 7

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Software Multiplexing (Application Layer) Many app-to-app connections over the same host-to -host connection Which functions are needed? Y N N N N Y
Image of page 8
Internet Hardware Multiplexing (Physical Layer) - 2Rs Reconnect Physically Which functions are needed? M G/R G/R M G/R G/R Y N N N N Y a b y z 4 sub-channels: ay, az, by, bz R R
Image of page 9

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Functions evolve to different layers Error & flow control Related Link quality Where? Poor Good Link wasted O/H Ends retransmit over entire network (many links)
Image of page 10
Systems Context What are the end to end protocols? What are the network layer protocols? How are network layer protocols different from link layer? End-to-end protocols Network layer protocol Link Layer Link Layer Link Layer
Image of page 11

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Link Layer Functions Provide service interface to the network layer Addressing Frames, fragments, & bit stuffing Flow control Error Control
Image of page 12
Services Provided to Network Layer Placement of the data link protocol. Remember, this might be a LAN; in which case, Layer 2 has additional work
Image of page 13

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Link Layer Addresses Physical delivery address Need only be locally unique Typically known as the MAC address Often physically embedded in Network Interface Card (NIC)
Image of page 14
Finding a Host on a Subnet Hosts are known to a subnet (eg. LAN) by their local attachment address (eg. Ethernet or MAC address) An IP address does not help deliver a packet
Image of page 15

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Finding a Host on a Subnet Solution: Make a table associating IP with network attachment addresses How?
Image of page 16
Image of page 17
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern