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Internet: network nodes

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Presentation on theme: "Internet: network nodes"— Presentation transcript:

1 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.

2 Internet: network of networks
star star hub bridge hub token ring switch bridge bridge Ethernet Ethernet router

3 Internet protocol stack vs. OSI model (Fig. 1.2)
Physical Layer Presentation Layer Session Layer Transport Layer Network Layer Data Link Layer Application Layer Process Layer , FTP, HTTP Host-to-host Layer TCP, UDP Internet Layer IP, ARP MAC* Layer Ethernet, Token ring (ATM, Frame Relay**) Physical Layer Manchester * 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 host Token ring host FTP client FTP protocol FTP server TCP TCP protocol TCP router IP IP protocol IP IP protocol IP Ethernet driver Ethernet protocol Ethernet driver Token ring driver Ethernet protocol Token ring driver Ethernet Token ring

5 Internet protocol suite
Telnet BOOTP HTTP DHCP TFTP SNMP FTP DNS RIP Process Layer Port Numbers / / / Host to Host Layer TCP UDP 6 17 ICMP 01 OSPF IGRP 88 Protocol Codes 89 Internet Layer ARP IP RARP 0806 0800 0806 Network Interface Layer Ethernet, Token Ring, FDDI, SLIP, PPP, etc.

6 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.

7 Encapsulation (Fig. 1.7) UDP 8 bytes variable Application Ethernet
20 to 60 bytes IP header TCP 20 or 24 variable Application CRC 4 bytes ICMP 6 + bytes

8 Demultiplexing (Fig. 1.8) application TCP IP Ethernet driver UDP ICMP
incoming frame IGMP RARP ARP

9 Sample (book) network Solaris 2.2 SunOS 4.1.1 aix .1.92 Cisco router
gemini gateway .1.32 .1.11 .1.4 Ethernet netb .1.183 Telebit NetBlazer modem All IP addresses belong to class B network ID SLIP (dialup) modem BSD/ BSD/ SunOS 4.1.3 .1.29 SVR4 slip bsdi sun svr4 .13.65 .13.66 .13.35 .13.33 .13.34 Ethernet

10 Link Layer (Fig. 2.1) SLIP (Serial Line IP) c0 db ESC c0 db dc db dd
Point-to-point (PPP) protocol Flag 7E addr FF Contr 03 Flag 7E protocol data CRC up to 0021 IP datagram C021 Link control data 8021 network control data

11 Ethernet Header Destin. Addr. Source Addr. Type
ff ff ff ff ff ff c0 a Broadcast Unicast ARP e c0 a Multicast Unicast IP c0 a c a c Unicast Unicast SNMP Vendor addr component Vendor ser. number

12 IP addressing convention
4 bytes (dec): = Class A: Large networks (GM, Ford, etc) N-Network bits L-Locally administered 126 Class A networks 16,777,214 hosts/network 0NNNNNNN LLLLLLLL LLLLLLLL LLLLLLLL 0 - unused, ; loop back Class B: medium size (universities, medium business) 16,384 Class B networks 65,534 hosts/network (0 not used, all 1’s broadcast) 10NNNNNN NNNNNNNN LLLLLLLL LLLLLLLL Class C: small networks (small business) 2,097,152 Class C networks 254 hosts/network 110NNNNN NNNNNNNN NNNNNNNN LLLLLLLL Class D: broadcasting 2,097,152 Class C networks 254 hosts/network 1110MMMM 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 I N - network bits S - subnet bits I - Interface bits. Natural masks: Class A : B : C :

14 Subnetting example Are this two hosts in the same subnet?
source: target: mask: 248 = mask 121 = source subn= source subnet 248 = target subn= target subnet

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