Presentation on theme: "Internet: network nodes"— Presentation transcript:
1 Internet: network nodes Host: any computer executing protocolHub: repeats signal heard one each port to all ports.Bridge: understands physical layer addresses, MAC addresses, and learns whereeach device is located. It listens to all traffic on LAN. If it finds that packet shouldgo to another segment it forwards the frame to it. It is store-and-forward device.Switch: same as bridge however much faster. It redirects a frame only after readingdestination address on a ongoing basis.Router: Internetwork layer device. It reads entire packet, based on destinationaddress finds the best route for the packet and sends it.
2 Internet: network of networks starstarhubbridgehubtokenringswitchbridgebridgeEthernetEthernetrouter
3 Internet protocol stack vs. OSI model (Fig. 1.2) Physical LayerPresentation LayerSession LayerTransport LayerNetwork LayerData Link LayerApplication LayerProcess Layer, FTP, HTTPHost-to-host LayerTCP, UDPInternet LayerIP, ARPMAC* LayerEthernet, Token ring (ATM, Frame Relay**)Physical LayerManchester* Medium Access Control. MAC and Physical layers are called Network Interface Layer.** not exactly MAC, however, layer above physical
4 Two networks connected with a router (Fig. 1.3) Ethernet hostToken ring hostFTPclientFTP protocolFTPserverTCPTCP protocolTCProuterIPIP protocolIPIP protocolIPEthernetdriverEthernetprotocolEthernetdriverToken ringdriverEthernetprotocolToken ringdriverEthernetToken ring
5 Internet protocol suite TelnetBOOTPHTTPDHCPTFTPSNMPFTPDNSRIPProcess LayerPort Numbers/ / /Host to HostLayerTCPUDP617ICMP01OSPFIGRP88ProtocolCodes89Internet LayerARPIPRARP080608000806NetworkInterfaceLayerEthernet, Token Ring, FDDI, SLIP, PPP, etc.
6 Internet protocolsTELNET - remote terminal connection service. Allows user terminal to mimic the terminalat the remote side.FTP - File Transfer Protocol (put/get file to/from remote machine).HTTP - Hypertext Transport Protocol.DNS - Domain Name Server On-line distributed database for translating IP machine namesinto IP addresses.BOOTP - Bootstrap Protocol defines each device autoconfiguration on the server (improvementto the RARP).DHCP - Dynamic Host Configuration Protocol (improvement to BOOTP) allows networkadministrator to configure workstation by providing dynamic address assignment.TFTP - Trivial File Transfer Protocol (same as FTP with minimal capability).SNMP - Simple Network Monitoring Protocol used to monitor IP gateways and networks theyare attached to.RIP - Routing Information Protocol used to exchange the routing information among smallset of computers (every 30 sec hosts exchange information).TCP - reliable Transmission Control Protocol (connection oriented).UDP - unreliable Universal Transport Protocol (connectionless).IGRP - Interior Gateway Routing Protocol (proprietary routing protocol developed by Cisco).ICMP - Internet Control Message Protocol part of IP that handles error and control messages.OSPF - Open Shortest Path First routing protocol.ARP - Address Resolution Protocol used to dynamically bind IP addresses to physical addresses.RARP - Reverse ARP used by newly installed machine to find its IP address.IP - Internet Protocol.
7 Encapsulation (Fig. 1.7) UDP 8 bytes variable Application Ethernet 20 to 60 bytesIP headerTCP20 or 24variableApplicationCRC4 bytesICMP6 + bytes
9 Sample (book) network Solaris 2.2 SunOS 4.1.1 aix .1.92 Cisco router geminigateway.188.8.131.52.1.4Ethernetnetb.1.183TelebitNetBlazermodemAll IP addresses belong to class B network ID xxx.xxxSLIP (dialup)modemBSD/BSD/SunOS 184.108.40.206.29SVR4slipbsdisunsvr220.127.116.11.18.104.22.168.33.13.34Ethernet
10 Link Layer (Fig. 2.1) SLIP (Serial Line IP) c0 db ESC c0 db dc db dd Point-to-point (PPP) protocolFlag7EaddrFFContr03Flag7EprotocoldataCRCup to0021IP datagramC021Link control data8021network control data
11 Ethernet Header Destin. Addr. Source Addr. Type ff ff ff ff ff ff c0 aBroadcastUnicastARPe c0 aMulticastUnicastIPc0 a c a cUnicastUnicastSNMPVendor addrcomponentVendor ser.number
12 IP addressing convention 4 bytes (dec): =Class A: Large networks (GM, Ford, etc)N-Network bitsL-Locally administered126 Class A networks16,777,214 hosts/network0NNNNNNN LLLLLLLL LLLLLLLL LLLLLLLL0 - unused, ; loop backClass B: medium size (universities, medium business)16,384 Class B networks65,534 hosts/network(0 not used, all 1’s broadcast)10NNNNNN NNNNNNNN LLLLLLLL LLLLLLLLClass C: small networks (small business)2,097,152 Class C networks254 hosts/network110NNNNN NNNNNNNN NNNNNNNN LLLLLLLLClass D: broadcasting2,097,152 Class C networks254 hosts/network1110MMMM MMMMMMMM MMMMMMMM MMMMMMMM
13 IP subnetting with subnet masks IP address:Subnet mask:Binary addr:Binary Mask:Address bits: NNNNNNNN NNNNNNNN SSSSSSI I I I I I I I I IN - network bitsS - subnet bitsI - Interface bits.Natural masks:Class A :B :C :
14 Subnetting example Are this two hosts in the same subnet? source:target:mask:248 = mask121 = sourcesubn= source subnet248 = targetsubn= target subnet