EE 122: Lecture 25 (Review)OverviewA Taxonomy of Communication NetworksBroadcast vs. Switched Communication NetworksSlide 5Circuit SwitchingTiming in Circuit SwitchingSlide 8Circuit Switching: Multiplexing/DemultiplexingSlide 10Packet SwitchingSlide 12Packet Switching: Multiplexing/DemultiplexingSlide 14Datagram Packet SwitchingTiming of Datagram Packet SwitchingSlide 17Slide 18Virtual-Circuit Packet SwitchingSlide 20Slide 21Slide 22Packet-Switching vs. Circuit-SwitchingFinal ExamSlide 25Router Architecture in Packet Switching NetworksData and Control PlanesTypical Functions Performed by Input Interface on Data PathTypical Functions Performed by Output InterfaceSlide 30Slide 31What is Layering?Why Layering?Slide 34LayeringISO OSI Reference ModelOSI vs. TCP/IPSlide 38End-to-End ArgumentExample: Reliable File TransferDiscussionSlide 42Trade-offsRule of ThumbInternet & End-to-End ArgumentKey AdvantagesEE 122: Lecture 25(Review)Ion StoicaDecember 6, [email protected] 2OverviewA taxonomy of communication networksRouter Architecture in Packet-Switching NetworksLayeringEnd-to-end [email protected] 3Communication networks can be classified based on the way in which the nodes exchange information:A Taxonomy of Communication NetworksCommunication NetworkSwitchedCommunication NetworkBroadcastCommunication NetworkCircuit-SwitchedCommunication NetworkPacket-SwitchedCommunication NetworkDatagram NetworkVirtual Circuit [email protected] 4Broadcast communication networks-Information transmitted by any node is received by every other node in the network•Examples: usually in LANs (Ethernet, Wavelan) -Problem: coordinate the access of all nodes to the shared communication medium (Multiple Access Problem)Switched communication networks-Information is transmitted to a sub-set of designated nodes•Examples: WANs (Telephony Network, Internet)-Problem: how to forward information to intended node(s) •this is done by special nodes (e.g., routers, switches) running routing protocols Broadcast vs. Switched Communication [email protected] 5Communication networks can be classified based on the way in which the nodes exchange information:A Taxonomy of Communication NetworksCommunication NetworkSwitchedCommunication NetworkBroadcastCommunication NetworkCircuit-SwitchedCommunication NetworkPacket-SwitchedCommunication NetworkDatagram NetworkVirtual Circuit [email protected] 6Circuit SwitchingThree phases1. circuit establishment2. data transfer3. circuit terminationIf circuit not available: “Busy signal”Example: telephone [email protected] 7Timing in Circuit SwitchingDATACircuit Establishment Data Transmission Circuit Termination Host 1 Host 2Node 1 Node 2propagation delay between Host 1 and Node 1propagation delay between Host 2 and Node 1processing delay at Node [email protected] 8Circuit SwitchingA node (switch) in a circuit switching networkincoming links outgoing [email protected] 9Circuit Switching: Multiplexing/DemultiplexingTime divided in frames and frames divided in slotsRelative slot position inside a frame determines which conversation the data belongs to -E.g., slot 0 belongs to red conversationNeed synchronization between sender and receiverIn case of non-permanent conversations-Need to dynamic bind a slot to a conservation-How to do this?If a conversation does not use its circuit the capacity is lost!Frames0 1 234 5 0 1 234 5Slots [email protected] 10Communication networks can be classified based on the way in which the nodes exchange information:A Taxonomy of Communication NetworksCommunication NetworkSwitchedCommunication NetworkBroadcastCommunication NetworkCircuit-SwitchedCommunication NetworkPacket-SwitchedCommunication NetworkDatagram NetworkVirtual Circuit [email protected] 11Packet SwitchingData are sent as formatted bit-sequences, so-called packets.Packets have the following structure:•Header and Trailer carry control information (e.g., destination address, check sum)Each packet is passed through the network from node to node along some path (Routing)At each node the entire packet is received, stored briefly, and then forwarded to the next node (Store-and-Forward Networks)Typically no capacity is allocated for packetsHeader [email protected] 12Packet SwitchingA node in a packet switching networkincoming links outgoing [email protected] 13Packet Switching: Multiplexing/DemultiplexingData from any conversation can be transmitted at any given time-A single conversation can use the entire link capacity if it is aloneHow to tell them apart?-Use meta-data (header) to describe [email protected] 14Communication networks can be classified based on the way in which the nodes exchange information:A Taxonomy of Communication NetworksCommunication NetworkSwitchedCommunication NetworkBroadcastCommunication NetworkCircuit-SwitchedCommunication NetworkPacket-SwitchedCommunication NetworkDatagram NetworkVirtual Circuit [email protected] 15Datagram Packet SwitchingEach packet is independently switched-each packet header contains destination addressNo resources are pre-allocated (reserved) in advanceExample: IP [email protected] 16Packet 1Packet 2Packet 3Packet 1Packet 2Packet 3Timing of Datagram Packet SwitchingPacket 1Packet 2Packet 3processing delay of Packet 1 at Node 2Host 1 Host 2Node 1Node 2propagationdelay betweenHost 1 and Node 2 transmission time of Packet 1at Host [email protected] 17Datagram Packet SwitchingHost AHost BHost EHost DHost CNode 1Node 2Node 3Node 4Node 5Node 6Node [email protected] 18Communication networks can be classified based on the way in which the nodes exchange information:A Taxonomy of Communication NetworksCommunication NetworkSwitchedCommunication NetworkBroadcastCommunication NetworkCircuit-SwitchedCommunication NetworkPacket-SwitchedCommunication NetworkDatagram NetworkVirtual Circuit [email protected] 19Virtual-Circuit Packet SwitchingHybrid of circuit switching and packet switching-data is transmitted as packets-all packets from one packet stream are sent along a pre-established path (=virtual circuit)Guarantees in-sequence delivery of packetsHowever: Packets from different virtual circuits may be
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