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Transcript
Internet: network nodes Host: any computer executing protocol Hub: repeats signal heard one each port to all ports. Bridge: understands physical layer addresses, MAC addresses, and learns where each device is located. It listens to all traffic on LAN. If it finds that packet should go 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 reading destination address on a ongoing basis. Router: Internetwork layer device. It reads entire packet, based on destination address finds the best route for the packet and sends it. Faruk Hadziomerovic: Internet notes Internet: network of networks star star hub bridge hub token ring switch bridge bridge Ethernet router Faruk Hadziomerovic: Internet notes Ethernet Internet protocol stack vs. OSI model (Fig. 1.2) Application Layer Presentation Layer Process Layer E-mail, FTP, HTTP Session Layer Transport Layer Host-to-host Layer Network Layer Internet Layer Data Link Layer MAC* Layer Physical Layer Physical Layer TCP, UDP IP, ARP Ethernet, Token ring (ATM, Frame Relay**) Manchester * Medium Access Control. MAC and Physical layers are called Network Interface Layer. ** not exactly MAC, however, layer above physical Faruk Hadziomerovic: Internet notes Two networks connected with a router (Fig. 1.3) Token ring host Ethernet host FTP protocol FTP client FTP server TCP protocol TCP TCP router IP Ethernet driver IP protocol Ethernet protocol IP protocol IP Ethernet driver Token ring driver Ethernet protocol IP Token ring driver Ethernet Token ring Faruk Hadziomerovic: Internet notes Internet protocol suite Process Layer Port Numbers T e l n e t 23 F T P H T T P D N S B O O T P 20/21 80 53 67/68 Host to Host Layer IGRP Internet Layer 88 ARP 0806 Network Interface Layer D H C P T F T P 69 TCP UDP 6 17 ICMP 01 IP 0800 S N M P 151/162 520 OSPF 89 RARP 0806 Ethernet, Token Ring, FDDI, SLIP, PPP, etc. Faruk Hadziomerovic: Internet notes R I P Protocol Codes Internet protocols TELNET - remote terminal connection service. Allows user terminal to mimic the terminal at 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 names into IP addresses. BOOTP - Bootstrap Protocol defines each device autoconfiguration on the server (improvement to the RARP). DHCP - Dynamic Host Configuration Protocol (improvement to BOOTP) allows network administrator 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 they are attached to. RIP - Routing Information Protocol used to exchange the routing information among small set 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. Faruk Hadziomerovic: Internet notes Encapsulation (Fig. 1.7) UDP 8 bytes Ethernet IP header 14 bytes 20 to 60 bytes TCP 20 or 24 Application variable Application variable ICMP 6 + bytes Faruk Hadziomerovic: Internet notes CRC 4 bytes Demultiplexing (Fig. 1.8) application application application TCP IGMP application UDP ICMP IP ARP RARP Ethernet driver incoming frame Faruk Hadziomerovic: Internet notes Sample (book) network Solaris 2.2 SunOS 4.1.1 solaris aix .1.92 gateway Cisco router gemini .1.32 .1.11 .1.4 Ethernet .1.183 netb Telebit NetBlazer All IP addresses belong to class B network ID 140.252.xxx.xxx modem SLIP (dialup) BSD/386 1.0 slip .13.65 BSD/386 1.0 .13.66 modem SunOS 4.1.3 .1.29 bsdi sun .13.35 .13.33 Ethernet Faruk Hadziomerovic: Internet notes SVR4 svr4 .13.34 Link Layer (Fig. 2.1) SLIP (Serial Line IP) c0 db ESC c0 db dc db dd c0 Point-to-point (PPP) protocol Flag 7E 1 addr FF 1 Contr 03 1 protocol 2 data up to 1500 0021 IP datagram C021 Link control data 8021 network control data Faruk Hadziomerovic: Internet notes CRC 2 Flag 7E 1 Ethernet Header Destin. Addr. ff ff ff ff ff ff 00 00 5e 00 00 00 00 00 c0 a0 Unicast a0 51 24 c0 a0 08 51 24 00 c0 93 21 51 24 08 00 IP 88 a7 Unicast Vendor addr component 06 ARP Unicast Multicast 01 00 c0 Unicast Broadcast 01 00 Type Source Addr. Vendor ser. number Faruk Hadziomerovic: Internet notes 81 4c SNMP IP addressing convention 4 bytes (dec): 140.252.1.13 = 01100000.10101010.00000001.00001011 Class A: Large networks (GM, Ford, etc) 0NNNNNNN LLLLLLLL LLLLLLLL LLLLLLLL 0 - unused, 1 .. 126 ; 127 - loop back N-Network bits L-Locally administered 126 Class A networks 16,777,214 hosts/network Class B: medium size (universities, medium business) 10NNNNNN NNNNNNNN 128 .. 191 0 .. 255 LLLLLLLL LLLLLLLL 16,384 Class B networks 65,534 hosts/network (0 not used, all 1’s broadcast) LLLLLLLL 2,097,152 Class C networks 254 hosts/network Class C: small networks (small business) 110NNNNN 192 .. 223 NNNNNNNN 0 .. 255 NNNNNNNN 0 .. 255 Class D: broadcasting 1110MMMM 224 .. 239 MMMMMMMM MMMMMMMM MMMMMMMM 0 .. 255 0 .. 255 0 .. 255 Faruk Hadziomerovic: Internet notes 2,097,152 Class C networks 254 hosts/network IP subnetting with subnet masks IP address: 191 255 193 44 Subnet mask: 255 255 252 000 Binary addr: 10111111 11111111 11000001 00101100 Binary Mask: 11111111 11111111 11111100 00000000 Address bits: NNNNNNNN NNNNNNNN SSSSSSI I N - network bits S - subnet bits I - Interface bits. Natural masks: Class A : 255.0.0.0 B : 255.255.0.0 C : 255.255.255.0 Faruk Hadziomerovic: Internet notes IIIIIIII Subnetting example Are this two hosts in the same subnet? source: 161.55.121.33 target: 161.55.131.49 mask: 255.255.248.0 248 = 11111000 mask 121 = 01111001 source subn= 01111 source subnet 248 = 11111000 mask 248 = 10000011 target subn= 10000 target subnet Faruk Hadziomerovic: Internet notes
