EECS 122: Introduction to Computer Networks Network Service and ApplicationsOverviewTaxonomy of Communication NetworksBroadcast vs. Switched Communication NetworksSlide 5Circuit SwitchingTelegraph NetworkTelephone NetworkTiming in Circuit SwitchingSlide 10Circuit Switching: Multiplexing/DemultiplexingSlide 12Packet SwitchingSlide 14Packet Switching: Multiplexing/DemultiplexingSlide 16Datagram Packet SwitchingTiming of Datagram Packet SwitchingSlide 19Slide 20Virtual-Circuit Packet SwitchingSlide 22Timing of Virtual-Circuit Packet SwitchingSlide 24Packet-Switching vs. Circuit-SwitchingSlide 26The Internet Protocol (IP)AddressingIP-centric ViewPhysical ViewBack to IPRoutingInternet ServiceDomain Name Service (DNS)File Transfer (FTP, SCP, etc.)EmailWebCachingContent Distribution Network (CDN)Gnutella (P2P)Gnutella (cont’d)Overlay NetworksArchitectureInternet Architecture1Katz, Stoica F04EECS 122: Introduction to Computer Networks Network Service and ApplicationsComputer Science DivisionDepartment of Electrical Engineering and Computer SciencesUniversity of California, BerkeleyBerkeley, CA 94720-17762Katz, Stoica F04Overview•Taxonomy of Communication Networks•Services and Applications3Katz, Stoica F04Communication networks can be classified based on the way in which the nodes exchange information:Taxonomy of Communication NetworksCommunication NetworkSwitchedCommunication NetworkBroadcastCommunication NetworkCircuit-SwitchedCommunication NetworkPacket-SwitchedCommunication NetworkDatagram NetworkVirtual Circuit Network4Katz, Stoica F04Broadcast Communication Networks-Information transmitted by any node is received by every other node in the network•Examples: usually in LANs (Ethernet, WiFi) -Problem: coordinate the access of all nodes to the shared communication medium (Multiple Access Problem)Switched Communication Networks-Information transmitted to a sub-set of designated nodes•Examples: WANs (Telephony Network, Internet)-Problem: how to forward information to intended node(s)? •Done by special nodes (e.g., routers, switches) executing routing protocols Broadcast vs. Switched Communication Networks5Katz, Stoica F04Communication networks can be classified based on the way in which the nodes exchange information:Taxonomy of Communication NetworksCommunication NetworkSwitchedCommunication NetworkBroadcastCommunication NetworkCircuit-SwitchedCommunication NetworkPacket-SwitchedCommunication NetworkDatagram NetworkVirtual Circuit Network6Katz, Stoica F04Circuit SwitchingThree phases1. circuit establishment2. data transfer3. circuit terminationIf circuit not available: “Busy signal”Examples-Telephone networks-ISDN (Integrated Services Digital Networks)7Katz, Stoica F04Telegraph NetworkAlexander Graham Bell-1876: Demonstrates the telephone at US Centenary Exhibition in Philadelphia8Katz, Stoica F04Telephone NetworkAlmon Brown Strowger (1839 - 1902)-1889: Invents the “girl-less, cuss-less” telephone system, aka the mechanical switching system9Katz, Stoica F04Timing 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 110Katz, Stoica F04Circuit SwitchingNode (switch) in a circuit switching networkincoming links outgoing linksNode11Katz, Stoica F04Circuit Switching: Multiplexing/DemultiplexingTime divided in frames and frames into slotsRelative slot position inside a frame determines to which conversation data belongs-E.g., slot 0 belongs to red conversationRequires synchronization between sender and receiver—surprisingly difficult!In case of non-permanent conversations-Needs to dynamically 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 =12Katz, Stoica F04Communication networks can be classified based on the way in which the nodes exchange information:Taxonomy of Communication NetworksCommunication NetworkSwitchedCommunication NetworkBroadcastCommunication NetworkCircuit-SwitchedCommunication NetworkPacket-SwitchedCommunication NetworkDatagram NetworkVirtual Circuit Network13Katz, Stoica F04Packet SwitchingData sent as formatted bit-sequences (Packets)Packets have following structure:•Header and Trailer carry control information (e.g., destination address, check sum)Each packet traverses 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 DataTrailer14Katz, Stoica F04Packet SwitchingNode in a packet switching networkincoming links outgoing linksNodeMemory15Katz, Stoica F04Packet Switching: Multiplexing/DemultiplexingData from any conversation can be transmitted at any given time-Single conversation can use the entire link capacity if it is aloneHow to tell them apart?-Use meta-data (header) to describe data16Katz, Stoica F04Communication networks can be classified based on the way in which the nodes exchange information:Taxonomy of Communication NetworksCommunication NetworkSwitchedCommunication NetworkBroadcastCommunication NetworkCircuit-SwitchedCommunication NetworkPacket-SwitchedCommunication NetworkDatagram NetworkVirtual Circuit Network17Katz, Stoica F04Datagram Packet SwitchingEach packet is independently switched-Each packet header contains destination addressNo resources are pre-allocated (reserved) in advanceExample: IP networks18Katz, Stoica F04Packet 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 119Katz, Stoica F04Datagram Packet SwitchingHost AHost BHost EHost DHost CNode 1Node 2Node 3Node 4Node 5Node 6Node 720Katz, Stoica F04Communication networks can be classified based on the way in which the nodes exchange information:Taxonomy of Communication NetworksCommunication NetworkSwitchedCommunication NetworkBroadcastCommunication NetworkCircuit-SwitchedCommunication NetworkPacket-SwitchedCommunication NetworkDatagram NetworkVirtual Circuit Network21Katz, Stoica F04Virtual-Circuit Packet SwitchingHybrid of
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