Andmeside IRT 0030 loeng sept. 2008

Transcription

1 Andmeside IRT 0030 loeng sept Avo Ots telekommunikatsiooni õppetool raadio- ja sidetehnika instituut avots@lr.ttu.ee 1

2 The Problem only nodes on the same physical/link layer network could communicate 2

3 Solution Gateways 3

4 Vahekihid Telnet FTP HTTP coaxial cable fiber optic packet radio Telnet FTP HTTP coaxial cable fiber optic packet radio 4

5 ISO OSI vs DoD mudel Process/ Application Host-to-Host Internet Network Access 5

6 Kihtide vahelised seosed rakendus esitlus Võrgurakenduse teenus seanss transport Transporditeenus võrk kanal füüsiline Võrguteenus 6

7 Virtuaalsed teed ja kanalid (VPI, VCI) VPI-10, 50 Mb/s STM Mb/s VCI-100 VCI-101 VCI-100 VCI-101 VPI-20, 60 Mb/s 7

8 Mudeli täiendused 7 Application e. g. Workflow 6 Presentation G.711 / G / G H.323 / H.450 / RTP 4 Transport TCP / UDP 3 Network IP DiffServ 2 Data Link MAC D 1 Physical Transmission Medium 8

9 Andmeülekanne (loogiline) data application transport network link physical application transport network link physical data ack application transport network link physical network link physical data application transport network link physical 9

10 Andmeülekanne (füüsiline) data application transport network link physical application transport network link physical application transport network link physical network link physical data application transport network link physical 10

11 Piirkonnad ja piirpinnad T T T GW GW SCN MCU GK GW T T 11

12 12

13 Sõnumiülekanne source destination Hl Ht HnHt HnHt M M M M application transport network link physical application transport network link physical Hl Ht HnHt HnHt M M M M message segment datagram frame 13

14 Vahekihid Telnet FTP HTTP coaxial cable fiber optic packet radio Telnet FTP HTTP coaxial cable fiber optic packet radio 14

15 Funktsioonijaotus The application knows the requirements best, place functionality as high in the layer as possible If the application can implement a functionality correctly, implement it at a lower layer only as a performance enhancement Think twice before implementing a functionality that you believe that is useful to an application at a lower layer 15

16 Töökindlus sender router receiver L2 L1 L1 L2 L1 Solution 1: make each step reliable, and then concatenate them Solution 2: end-to-end check and retry 16

17 Töökindluse tagamine The receiver has to do the check anyway! Thus, full functionality can be entirely implemented at the upper layer; no need for reliability from lower layers Is there any need to implement reliability at lower layers? sender receiver L2 L1 L1 L2 L1 17

18 Collapsed backbone 18

19 Central Parking s collapsed backbone 19

20 Protokollid

21 Simple Mail Transfer Protocol RFC0821 (august 1982) J. Postel, RFC2821 (aprill, 2001) Sõnumite töökindlaks saatmiseks Klient-server mudel Ühendusele orienteeritud ja kinnitustega protokoll TCP port 25 21

22 Components Independent Independent Block Block Independent Independent Block Block Independent Independent Block Block Independent Independent Block Block Independent Independent Block Block Control Logic Logic Logic Logic Switching Switch Switch Switch Switch Switch Switch Switch Switch Access Access Access Access Access Access Access Access Access Access Access Control (Circuit Switching control) 22

23 Terminal Terminal Off-line Off-line customer customer management management Extended Extended call call control control and and IN IN charging charging Telecom Telecom basic basic service/call service/call control control Terminal Terminal Access Access Transmission Transmission Access Access Linear Architecture in Legacy Network: Static s A User User Management Management A Home Home BHome BHome B User User Management Management A Terminal Terminal A Portal Access Access Control Control Transmission Transmission Access Access B Portal B Terminal Terminal Two-Dimension Architecture in NGN: Active s 23

24 24

25 Lõpulingid Kõik RFC-d: