1 / 17

RECITATION 3

RECITATION 3. Remind: CEREAL account!!!. Project 1. Provide TorrentFileHandle.java & … Important info from .torren file url of the tracker Name of file Length of file Pieces <hash1,hash2,….hashn> Piece length. Tracker. Web Server. Web page with link to .torrent. Get-announce. C.

laurel
Download Presentation

RECITATION 3

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. RECITATION 3 Remind: CEREAL account!!!

  2. Project 1 • Provide TorrentFileHandle.java & … • Important info from .torren file • url of the tracker • Name of file • Length of file • Pieces <hash1,hash2,….hashn> • Piece length

  3. Tracker Web Server Web page with link to .torrent Get-announce C A Peer [Seed] Peer [Leech] Downloader “US” B Peer [Leech] Overall Architecture

  4. Tracker Web Server Web page with link to .torrent Response-peer list C A Peer [Seed] Peer [Leech] Downloader “US” B Peer [Leech] Overall Architecture

  5. Tracker Web Server Web page with link to .torrent Shake-hand C A Peer [Seed] Peer [Leech] Downloader “US” Shake-hand B Peer [Leech] Overall Architecture

  6. Overall Architecture Tracker Web Server Web page with link to .torrent request C A request Peer [Seed] Peer [Leech] Downloader “US” B Peer [Leech]

  7. Tracker Web Server Web page with link to .torrent pieces C A pieces Peer [Seed] Peer [Leech] Downloader “US” B Peer [Leech] Overall Architecture

  8. Project 1 Basics (cont'd) ● Communicate With Peer – Handshake <pstrlen><pstr><reserved><info_hash><peer_id> – General Messages <length prefix [4B dec]><message ID[1B char]><payload> – Request <0013><6><index><begin><length> – Piece: <length prefix> is 0009+X and message ID is 7. The payload is as follows: <index><begin><block> X is block size

  9. Sample Question: SWITCHING • Considering a small network of four hosts and three links as depicted in the figure below. A 1MB message is to be sent from A to D. The bandwidth of links is 0.8 Mbyte/second. Propagation delays of the links are negligible. • Host A ----- Host B------ Host C----------Host D • (A). Assume that circuit switching is used and the total circuit set-up time is 100 ms, what is the time to send the message from A to D? • (B). Assume that message switching is used and queuing delays are negligible, what is the time to send the message from A to D?

  10. Sample Question: SWITCHING+PIPELINING Considering a small network of four hosts and three links as depicted in the figure below. A 1MB message is to be sent from A to D. The bandwidth of links is 0.8 Mbyte/second. Propagation delays of the links are negligible. Host A ----- Host B------ Host C----------Host D (C). Assume that packet switching is used, packet size is 240 bytes and header size is 10 bytes, what is the time to send the message from A to D? (WITH PIPELINING)

  11. Msg Msg Msg Message Switching (cont’d) Header Transmission Delay Time Queueing Delay A B C D Routers/switches

  12. Pipelining “Parallelogram” for packet switching Host A Switch 1 Switch 2 Host B Packet 1 Packet 2 Packet 3 Time Packet 4

  13. Sample Question: Performance Analysis For parts A and B, assume host A is connected to B via a point-to-point duplex link which has a data rate of 1 Mbps and propagation delay of 10 msec. HOST A------------------------------HOST B Host A has a large amount of data that must be reliably sent to Host B. Assuming Stop-and-Wait protocol is used to assure reliable delivery, the data frame size is 1000 bytes each, and the ACK frame size is 64 bytes. (A). Assuming that Host B takes 0 time to process an incoming data and send an ACK frame back to A, what is the smallest time the retransmission timer can be set to at Host A which eliminates unnecessary retransmissions? (B). Assuming there are no transmission errors, what is the link utilization in the direction from A to B? Hint: • Link utilization = the time to send a frame without delay and ACK/ the time in A (OR the time to send a frame from A to B + the time an ACK frame back to A) • Link utilization = size of a frame/ (the time to send a frame from A to B + the time an ACK frame back to A) (C). A new, different channel has a bit rate of 4 Kbps and a propagation delay of 20 msec. For what range of frame sizes does stop-and-wait protocol give an efficiency of at least 50 percent?

  14. MAC address • Network Interface Card (NIC) • Each NIC has its own MAC address , it is stored on the chip!! • Length of MAC : 48 bites = 6 bytes • For examples: 00:C1:71:01:AB:F0 • Prefix: Company ID: 3Com, Netgear … • Postfix: Serial Number • Command to show MAC: ifconfig, ipconfig

  15. Ethernet Frame Structure • Type(2 bytes) specifies the network layer protocol: IP or Novel IPX or ARP or RARP… • CRC: check sum • Broadcast: • MAC Broadcast Address = FF:FF:FF:FF:FF:FF • Host A sends a msg to host B: • MAC dest = MAC B, MAC src = MAC A

  16. forward send send HUB vs. SWITCH Ethernet Frame SWITCH can learn the MACs of all nodes MAC A -> MAC C DATA HUB SWITCH A B C A B C B can CAPTURE the packet from A to C !!!! B CAN’T capture the packet from A to C !!!!

  17. How to build your own network! • NICs • HUB or SWITCH !!! • 2 machines can be connected by using crossover cable!!! • Assign IP address • Static • Dynamic Crossover cable

More Related