1. 1 IEX8175 RF Electronics Avo Ots telekommunikatsiooni õppetool, TTÜ raadio- ja sidetehnika inst. avo.ots@ttu.ee

2. 2 Network Engineering The process concerned with optimally selecting topology and bandwidth in a layer network, based on –(pro-active) traffic demands expected between any two locations in the network and –(re-active) the actual traffic demand It is an inter layer network process NwE process in each layer network –advertises the nodes and their ports within the layer network –monitors the layer network and determines if/when a new (topological) link should be added or an existing link should be modified or released, based on the network provider's policy –determines best set of connections between ports in the layer network –requests those connections to be set up by its server layer networks; i.e. generates outgoing calls for client connections It is implemented by the (distributed) Network Engineering Controllers (NEC) within the layer network

3. 3 Shared & Dedicated B W

4. 4 Internet protocol Provides best effort, connectionless packet delivery –motivated by need to keep routers simple and by adaptibility to failure of network elements –packets may be lost, out of order, or even duplicated –higher layer protocols must deal with these, if necessary RFCs 791, 950, 919, 922, and 2474. Internet STD also includes: –Internet Control Message Protocol (ICMP), RFC 792 –Internet Group Management Protocol (IGMP), RFC 1112

5. 5 IP address R Network 128.135.0.0 Network 128.140.0.0 H H H H H R = router H = host Interface Address is 128.135.10.2 Interface Address is 128.140.5.35 128.135.10.20128.135.10.21 128.135.40.1 128.140.5.36 128.140.5.40 Address with host ID=all 0s refers to the network Address with host ID=all 1s refers to a broadcast packet

6. 6 1 2 3 4 5 6 Node (switch or router) Routing in Packet Networks Three possible (loopfree) routes from 1 to 6: –1-3-6, 1-4-5-6, 1-2-5-6 Which is “best”? –Min delay? Min hop? Max bandwidth? Min cost? Max reliability?

7. 7 Packet Switch: Meet 1 2 N 1 2 N Inputs contain multiplexed flows from access muxs & other packet switches Flows demultiplexed at input, routed and/or forwarded to output ports Packets buffered, prioritized, and multiplexed on output lines

8. 8 Controller 1 2 3 N Line card Interconnection fabric Line card 1 2 3 N Input portsOutput ports Data path Control path (a) … … … … Generic Packet Switch “Unfolded” View of Switch Ingress Line Cards –Header processing –Demultiplexing –Routing in large switches Controller –Routing in small switches –Signalling & resource allocation Interconnection Fabric –Transfer packets between line cards Egress Line Cards –Scheduling & priority –Multiplexing

9. 9 1 2 3 N 1 2 3 N … Shared Memory Queue Control Ingress Processing Connection Control … Shared Memory Packet Switch Output Buffering Small switches can be built by reading/writing into shared memory

10. 10 1 2 3 N 123N Inputs Outputs (a) Input buffering 38 3 … … 1 2 3 N 123N Inputs Outputs (b) Output buffering … … Crossbar Switches Large switches built from crossbar & multistage space switches Requires centralized controller/scheduler (who sends to whom when) Can buffer at input, output, or both (performance vs complexity)

11. 11 UDP Multiplexing All UDP datagrams arriving to IP address B and destination port number n are delivered to the same process... UDP IP 12n... UDP IP 12n... UDP IP 12n A BC

12. 12 Congestion Control Buffers at intermediate routers between source and destination may overflow Router R bps Packet flows from many sources Congestion occurs when total arrival rate from all packet flows exceeds R over a sustained period of time

13. 13 Phases of Congestion Behavior 1. Light traffic –Arrival Rate << R –Low delay –Can accommodate more 2.Knee (congestion onset) –Arrival rate approaches R –Delay increases rapidly –Throughput begins to saturate 3.Congestion collapse –Arrival rate > R –Large delays, packet loss –Useful application throughput drops Throughput (bps) Delay (sec) R R Arrival Rate

14. 14 Compute Communicate Store Communicate Communications and computing

15. 15 Compute Sense Environment Act Communicate Store Communicate

16. 16 Computation Devices Dynamical Systems Devices Communication Control

17. 17 From Software to/from human Human in the loop To Software to Software Full automation Integrated control, comms, computing Closer to physical substrate Compute Communicate Store Communicate Computation Devices Dynamical Systems Devices Communication Control New capabilities & robustness New vulnerabilities

18. 18 IPv4 >to>> IPv6 Expanded addressing capabilities Header format simplification Improved support for extensions and options Flow labelling capability Authentication and privacy capabilities

19. 19 Basic Headers IPv6 Header IPv4 Header

20. 20 Basic Headers Fields –Version (4 bits) – only field to keep same position and name –Class (8 bits) – new field –Flow Label (20 bits) – new field –Payload Length (16 bits) – length of data, slightly different from total length –Next Header (8 bits) – type of the next header, new idea –Hop Limit (8 bits) – was time-to-live, renamed –Source address (128 bits) –Destination address (128 bits)

21. 21 Basic Headers Simplifications –Fixed length of all fields, not like old options field – IHL, or header length irrelevant –Remove Header Checksum – rely on checksums at other layers –No hop-by-hop fragmentation – fragment offset irrelevant – MTU discovery –Add extension headers – next header type (sort of a protocol type, or replacement for options) –Basic Principle: Routers along the way should do minimal processing

22. 22 Extension Headers Extension Header Types –Routing Header –Fragmentation Header –Hop-by-Hop Options Header –Destinations Options Header –Authentication Header –Encrypted Security Payload Header

23. 23 Lõpulingid http://www.ietf.org/rfc/rfc0791.txt?number=791 http://www.ietf.org/rfc/rfc2474.txt?number=2474 http://www.apple.com/airportextreme/specs.html http://tools.ietf.org/html/rfc1924

24. 24 Links http://www.ietf.org/rfc/rfc0791.txt?number=791 http://www.ietf.org/rfc/rfc2474.txt?number=2474 http://www.apple.com/airportextreme/specs.html http://tools.ietf.org/html/rfc1924