Contents Link multiplexing Circuit switching Synchronous Timedomain Multiplexing

  • Slides: 14
Download presentation
Contents • Link multiplexing – Circuit switching • Synchronous Time-domain Multiplexing – Packet Switching

Contents • Link multiplexing – Circuit switching • Synchronous Time-domain Multiplexing – Packet Switching • Statistical Time-domain Multiplexing • Connection oriented vs. Connectionless – Datagrams & Routing – Virtual Circuits & Forwarding • Internal vs. External policies Postacademic Interuniversity Course in Information Technology – Module C 1 p 1

Connection oriented vs. Connectionless • Circuit Switching – Intrinsically connection oriented • Packet Switching

Connection oriented vs. Connectionless • Circuit Switching – Intrinsically connection oriented • Packet Switching – Connectionless • Each packet carries the destination address • Routing decisions to be made for each packet • Typical example : Internet Protocol – Connection oriented : Virtual Circuits • Each packet carries a local identifier (VCN) of the data flow it belongs to • Routing decisions at virtual circuit set-up. • Typical examples : X 25, Frame Relay, ATM Postacademic Interuniversity Course in Information Technology – Module C 1 p 2

Contents • Link multiplexing – Circuit switching • Synchronous Time-domain Multiplexing – Packet Switching

Contents • Link multiplexing – Circuit switching • Synchronous Time-domain Multiplexing – Packet Switching • Statistical Time-domain Multiplexing • Connection oriented vs. Connectionless – Datagrams & Routing – Virtual Circuits & Forwarding • Internal vs. External policies Postacademic Interuniversity Course in Information Technology – Module C 1 p 3

Datagram Routing Based upon routing tables 3 a 1 2 b 3 c 3

Datagram Routing Based upon routing tables 3 a 1 2 b 3 c 3 2 1 4 a: 1 b: 2 c: 3 d: 3 1 3 4 2 a: 3 b: 3 c: 2 d: 2 Postacademic Interuniversity Course in Information Technology – Module C 1 a: 3 b: 3 c: 1 d: 2 1 2 d p 4

Routing Tables in Connectionless networks • For ALL POSSIBLE destination addresses, they give the

Routing Tables in Connectionless networks • For ALL POSSIBLE destination addresses, they give the “best” outgoing link, but – the best can be different for different applications – the best can get congested • For EACH packet routing table needs to be consulted • Routing tables need to be updated regularly – Set of possible destinations can change – Set of available links can change – Destinations can be mobile Postacademic Interuniversity Course in Information Technology – Module C 1 p 5

Best route consequences 1 a 1 1 b 1 Idle c 1 Risk of

Best route consequences 1 a 1 1 b 1 Idle c 1 Risk of congestion Postacademic Interuniversity Course in Information Technology – Module C 1 d p 6

Contents • Link multiplexing – Circuit switching • Synchronous Time-domain Multiplexing – Packet Switching

Contents • Link multiplexing – Circuit switching • Synchronous Time-domain Multiplexing – Packet Switching • Statistical Time-domain Multiplexing • Connection oriented vs. Connectionless – Datagrams & Routing – Virtual Circuits & Forwarding • Internal vs. External policies Postacademic Interuniversity Course in Information Technology – Module C 1 p 7

Virtual Circuit Number a b a>b 10 a>c 11 a>d 12 b>c 11 b>d

Virtual Circuit Number a b a>b 10 a>c 11 a>d 12 b>c 11 b>d 12 a>b 21 b>c 20 a>c 21 d>c 22 a>c a>d b>c b>d 10 11 12 13 d>c 11 a>d 20 b>d 21 c d Each virtual circuit is identified by a specific number on each physical link Postacademic Interuniversity Course in Information Technology – Module C 1 p 8

Forwarding Tables 11 a 1 3 2 1. 11>3. 10 21 10 b Postacademic

Forwarding Tables 11 a 1 3 2 1. 11>3. 10 21 10 b Postacademic Interuniversity Course in Information Technology – Module C 1 1 1. 10>3. 21 c 3 2 d p 9

Permanent Virtual Circuit Forwarding tables set-up and cleared by network manager through “separate” network

Permanent Virtual Circuit Forwarding tables set-up and cleared by network manager through “separate” network a>c 21 a a>c 11 c 1 3 2 1. 11>3. 10 b 1 1. 10>3. 21 “Separate” signaling network 3 2 d Signaling and data packets travel through different (virtual) circuits Postacademic Interuniversity Course in Information Technology – Module C 1 p 10

Forwarding Tables in Connection Oriented networks • For Each V. C. in use, they

Forwarding Tables in Connection Oriented networks • For Each V. C. in use, they give the outgoing link – Different v. c. can connect the same end-points. – Resources can be reserved for a v. c. – They can be changed dynamically to follow mobiles • Routing tables are only needed to establish a new V. C. Postacademic Interuniversity Course in Information Technology – Module C 1 p 11

Contents • Link multiplexing – Circuit switching • Synchronous Time-domain Multiplexing – Packet Switching

Contents • Link multiplexing – Circuit switching • Synchronous Time-domain Multiplexing – Packet Switching • Statistical Time-domain Multiplexing • Connection oriented vs. Connectionless – Datagrams & Routing – Virtual Circuits & Forwarding • Internal vs. External policies Postacademic Interuniversity Course in Information Technology – Module C 1 p 12

Internal vs. External Policies Network services (NUI) Connection oriented Connectionless Postacademic Interuniversity Course in

Internal vs. External Policies Network services (NUI) Connection oriented Connectionless Postacademic Interuniversity Course in Information Technology – Module C 1 Network operation (NNI) Connection oriented Connectionless p 13

Introduced concepts • • • Multiplexing Circuit Switching Synchronous time multiplexing Packet Switching Statistical

Introduced concepts • • • Multiplexing Circuit Switching Synchronous time multiplexing Packet Switching Statistical time multiplexing Datagrams and routing Virtual Circuits & packet forwarding Resource reservation for a Virtual Circuit Internal vs. External policies Postacademic Interuniversity Course in Information Technology – Module C 1 p 14