Unit 6. Author: W.Buchanan. IP The Address (1)

Transcription

1 Unit 6 Author: W.Buchanan. IP The Address (1)

2 Author: W.Buchanan. IP The Address (2) IP TTL=255 TTL=12 TTL=200 TTL=25 TTL stops the data packet from transversing the Internet forever. TTL=190 TTL=170 TTL=50

3 Author: W.Buchanan. IP The Address (3) Mobile s (Unit 10) Router Programming (Unit 8) Routing Protocols (Unit 9) IP Addressing/Subnets (Unit 6) TCP/Socket Programming (Unit 7) Switches/VLANs (Unit 5) Net Elements (Unit 2) Net Types (Unit 3) Net Design (Unit 4) Introduction (Unit 1)

4 application application program program Application Application Application program program makes makes contact contact with with network network application application for for Hello. Fred. Physical The The data data frame frame is is converted converted into into binary binary form form and and transmitted transmitted over over a a physical physical connection connection Start Start Start Presentation Convert Convert data data into into a a form form which which can can be be transmitted transmitted To: Fred From: Bert Hello. Fred. Addr Addr Addr Seg 1 Seg 2 Seg 3 Data link End End End Data Data packet packet converting converting into into a a form form which which can can be be transmitted transmitted over over the the network network Data encapsulation Session Contact Contact remote remote system system and and request request a a transmission transmission HELO sys.com FOR Fred To: Fred From: Bert Hello. Fred. Add Add source source and and destination destination addresses addresses Addr Addr Addr Transport Negotiate Negotiate data data transfer transfer and and split split data data into into segments segments Seg 1 Seg 2 Seg 3 Seg 1 Seg 2 Seg 3 Author: W.Buchanan. IP The Address (4)

5 Author: W.Buchanan. IP The Address (5) address Place Street City Edinburgh Castle, 10 Princes Street, Edinburgh EH1 1LZ Physical address OS Grid Co-ordinate: 03434, 75321

6 Analogy Author: W.Buchanan. IP The Address (6) Session Transport Name:MyBook Chapter: 1 Document is split into chapters I m I m sending it, it, now. Name:MyBook Chapter: 2 What s the maximum size of the documents that can be sent? Name:MyBook Chapter: n Address: 1 High St Address: 1 High St Address: 1 High St

7 Author: W.Buchanan. IP The Address (7) (Logical address) Sorting Office Sorting Office Sorting Office Data link Physical Actual (Physical address) Throughout the network address stays the same, but the physical address changes

8 Author: W.Buchanan. IP The Address (8) Sorting Office Postal Sorting Office Only at the end does the physical address and the logical address have to be resolved. The actual physical address is finally resolved

9 Analogy Author: W.Buchanan. IP The Address (9) Session Thanks. I ve I ve received it. it. Transport Name:MyBook Chapter: 3 Document is reassembled Name:MyBook Chapter: 5 Name:MyBook Chapter: 1 Address: 1 High St Address: 1 High St Address: 1 High St

10 Analogy Author: W.Buchanan. IP The Address (10) 1 2 Data segments (TCP) Data packets (IP) Internet Ethernet Only at the end does the physical address and the logical address have to be resolved. The actual physical address is finally resolved

11 IP and MAC Addresses Author: W.Buchanan. IP The Address (11) MAC1, IP1 IP Src: IP1 IP Dest: IP8 MAC Src: MAC1 MAC Dest: MAC2 MAC2, IP2 The IP addresses stay the same but the MAC address changes MAC3, IP3 MAC4, IP4 IP Src: IP1 IP Dest: IP8 MAC Src: MAC3 MAC Dest: MAC4 MAC5, IP5 MAC6, IP6 IP Src: IP1 IP Dest: IP8 MAC Src: MAC5 MAC Dest: MAC6 MAC7, IP7 MAC8, IP8 IP Src: IP1 IP Dest: IP8 MAC Src: MAC7 MAC Dest: MAC8

12 IP and MAC Addresses Author: W.Buchanan. IP The Address (12) [Gateway is the port of the router] MAC1, IP1 MAC2, IP2 Each network segment determines MAC addresses of gateways by sending and ARP broadcast. MAC3, IP3 MAC4, IP4 MAC5, IP5 MAC6, IP6 MAC7, IP7 MAC8, IP8 ARP broadcasts

13 IP and TCP Author: W.Buchanan. IP The Address (13) IP address is used to route data around the Internet TCP part allows applications to communicate over the network Data Data Link Link Physical Physical A router routes with the network address (such as the IP address)

14 IP header IP IP TCP TCP Higher-level protocol/data Data Packet Version Header Header length length Total length Identification Type of of service 0 D M Fragment Offset Time-to-Live Header Checksum Source IP IP Address Destination IP IP Address Protocol Source IP address Routers route with the destination address Destination IP address Author: W.Buchanan. IP The Address (14)

15 IP header IP IP TCP TCP Higher-level protocol/data Data Packet (IPv4) Version Header Header length length Total length Identification Type of of service 0 D M Fragment Offset Time-to-Live Header Checksum Source IP IP Address Destination IP IP Address Protocol The first thing that is read is the version. IPv4 uses a 32-bit address. IPv6 uses a 32-bit address Author: W.Buchanan. IP The Address (15)

16 IP header IP IP Version TCP TCP Header Header length length Total length Identification Higher-level protocol/data Type of of service 0 D M Fragment Offset Time-to-Live Header Checksum Source IP IP Address Destination IP IP Address Protocol Data Packet A datagram could propagate through the internet indefinitely. To prevent this, the 8-bit time-to-live value is set to the maximum transit time in seconds and is set initially by the source IP. Each gateway then decrements this value by a defined amount. When it becomes zero the datagram is discarded. It also defines the maximum amount of time that a destination IP node should wait for the next datagram fragment. Author: W.Buchanan. IP The Address (16)

17 Time-to-live field Author: W.Buchanan. IP The Address (17) TTL=255 TTL=12 TTL=200 TTL=25 TTL stops the data packet from transversing the Internet forever. TTL=190 TTL=170 TTL=50

18 IP header IP IP TCP TCP Higher-level protocol/data Data Packet Version Header Header length length Total length Identification Type of of service 0 D M Fragment Offset Time-to-Live Header Checksum Source IP IP Address Destination IP IP Address Protocol Protocol (8 bits). Different transport protocols can be used on the datagram. The 8-bit protocol field defines the type to be used. E.g. 1 ICMP and 6 TCP Author: W.Buchanan. IP The Address (18)

19 IP can support many different upper-layer protocols Author: W.Buchanan. IP The Address (19) UDP TCP Voice over IP NetBIOS over IP IPX/SPX over IP ICMP (ping, tracert) Internet The Internet can support many different higher-layer protocols, not just TCP

20 IP header IP IP TCP TCP Higher-level protocol/data Data Packet (IPv4) Version Header Header length length Total length Identification Type of of service 0 D M Fragment Offset Time-to-Live Header Checksum Source IP IP Address Protocol Very basic Checksum. Thus, there Is very little error checking/ verification. Destination IP IP Address Author: W.Buchanan. IP The Address (20)

21 IP header IP IP TCP TCP Higher-level protocol/data Data Packet Version Header Header length length Total length Identification Type of of service 0 D M Fragment Offset Time-to-Live Header Checksum Source IP IP Address Protocol IPv4 address Is 32 bits long. - which only Gives up to 4 billion addresses (2 32 ) Destination IP IP Address Author: W.Buchanan. IP The Address (21)

22 IP address classifications Author: W.Buchanan. IP The Address (22) 32 bits Host 8 bits Binary notation Dotted notation (W.X.Y.Z) Class A NET(0 127) NET(0 127) HOST HOST HOST HOST HOST HOST Class B NET NET (128 ( ) 191) NET NET HOST HOST HOST HOST Class C NET NET (192 ( ) 223) NET NET NET NET HOST HOST

23 TCP/IP Intranet MARS MOON A VAX01 VAX02 MERCURY JUPITER ETHER C Router Router Responsible Responsiblefor for examining examining IP IP address address to to determine determine if if the the TCP/IP TCP/IP packet packet must must be be routed routed out out of of the the network, network, and and the the main main network. network. Router Routermust have have two two IP IP addresses addresses as as it it is is part part of of two two network network segments segments B PLUTO VENUS OBERON DIONE Author: W.Buchanan. IP The Address (23)

24 Author: W.Buchanan. IP The Address (24) IP Address Types IP IP Address Address Ranges Ranges Host Host Class Class A: A: to to (127 (127 networks) networks) (16,711,680 (16,711,680 hosts) hosts) Class Class B: B: to to to to (16,320 (16,320networks) (65,024 (65,024hosts) Class Class C: C: to to to to (2,088,960 (2,088,960 networks) networks) (255 (255 hosts) hosts) 0 0 Class A (7 bits) Node (24 bits) Class B (14 bits) Node (16 bits) Class C (21 bits) Node (8 bits)

25 TCP/IP Intranet Author: W.Buchanan. IP The Address (25) w.x.y.z IP address Number Number Host Host Number Number w.x A [ [ Number] Number] Global network B [ [ Number] Number] [Host Number] C [ [ Number] Number]

26 Author: W.Buchanan. IP The Address (26) IP address (Type B) Number Number TCP/IP Intranet with Subnets Subnet Subnet Host Host Number Number Number Number PC419: Typical Typical Subnet Subnet masks masks Class Class A: A: Class Class B: B: Class Class C: C: Subnet Subnet A [Subnet [Subnet Number] Number] W.X.Y Subnet Subnet A [Subnet [Subnet Number] Number] W.X.Y.Z A [ [ Number] Number] W.X Global network Subnet Subnet A [Subnet [Subnet Number] Number] B [ [ Number] Number] Napier: [Host Number] Lab Block: Subnet Subnet B [Subnet [Subnet Number] Number] Computing main block:

27 Class A IP Address Author: W.Buchanan. IP The Address (27) Internet s: Few Net. 127 IP IP Address Address Ranges Ranges Host Host Class Class A: A: to to (127 (127 networks) networks) (16,711,680 (16,711,680 hosts) hosts) Class Class B: B: to to to to (16,320 (16,320networks) (65,024 (65,024hosts) Class Class C: C: to to to to (2,088,960 (2,088,960 networks) networks) (255 (255 hosts) hosts) Class A : Host: Few networks, and many hosts s: Many 1 16,711,680

28 Class B IP Address Author: W.Buchanan. IP The Address (28) Internet s: Average Net. 16,320 IP IP Address Address Ranges Ranges Host Host Class Class A: A: to to (127 (127 networks) networks) (16,711,680 (16,711,680 hosts) hosts) Class Class B: B: to to to to (16,320 (16,320networks) (65,024 (65,024hosts) Class Class C: C: to to to to (2,088,960 (2,088,960 networks) networks) (255 (255 hosts) hosts) Class B : Host: Large number of networks, large number of host (although not as many as Class A) s: Average 1 65,024

29 Class C IP Address Author: W.Buchanan. IP The Address (29) Internet s: Many Net. 2,088,960 IP IP Address Address Ranges Ranges Host Host Class Class A: A: to to (127 (127 networks) networks) (16,711,680 (16,711,680 hosts) hosts) Class Class B: B: to to to to (16,320 (16,320networks) (65,024 (65,024hosts) Class Class C: C: to to to to (2,088,960 (2,088,960 networks) networks) (255 (255 hosts) hosts) Class C : Host: Large number of networks, and few hosts s: Few 1 255

30 addresses, and broadcasting Author: W.Buchanan. IP The Address (30) (Class A network address) (Class B network address) (Class C network address). Addresses The address used to represent the whole of a network Net Net W.Z.Y.0 W.Z.Y.0 Net Net W.Z.0.0 W.Z.0.0 Net Net W W Net Net W.Z.0.0 W.Z (Class A broadcast into ) (Class A broadcast into ) (Class C broadcast into ). Broadcast Addresses All nodes on the addressed network will listen to the transmission

31 Subnetting masks for Class B addresses Author: W.Buchanan. IP The Address (31) Subnet address Dotted not. Max sub. Max hosts (/subnet) For example, if the network address is and the five bits are used for the subnet mask then: The network {00001} is the first subnet (node range to ) and {11110} is the last subnet (node range to )

32 Example Domain Naming Structure edu edu com com gov gov mil mil de de uk uk fr fr Primary domain intel intel sony sony nec nec co co ac ac org org www www res res sales sales ed ed napier napier hw hw eece eece dcs dcs mmse mmse pc01 pc01 sun01 sun01 www www pc01 pc01 pc01.eece.napier.ac.uk Example Example DNS DNS mappings mappings Domain Domain name name IP IP address address web.nec.com web.nec.com Author: W.Buchanan. IP The Address (32)

33 Domain name server Author: W.Buchanan. IP The Address (33) Once WWW browser has the IP address of the destination, it can then access it DNS may interrogate Other DNS s to Determine IP addresses Internet WWW browser asks The DNS for the IP address of the domain name DNS returns back the IP address of the domain name Domain name server

34 Allocating IP addresses Author: W.Buchanan. IP The Address (34) Limiting access to the Internet. IP addresses can be mapped to MAC addresses. A node which requires an IP address will ask the IP granting server for an IP address. The server then checks the host s MAC address to determine if it is allowed to access the Internet. If it is not, the server does not return an IP address. The system administrator can thus set up a table which only includes the hosts which are required to connect to the Internet. Authenticating nodes. A typical hacking method is to steal an IP address and use it for the time of a connection. This can be overcome by making all of the nodes on the network ask the IP granting server for their IP address. It is thus not possible to steal an address, as the IP granting server will check the MAC address of the host. Allocating from a pool of IP addresses. An organization may be granted a limited range of IP addresses which is not enough to allocate to all the nodes in the organization. The IP granting server can thus be set up to allocate IP addresses to nodes as they require them. When all the IP addresses have been allocated, no more IP addresses can be given out. When a node is finished with its IP address, the IP address that was granted to it can be put back in the pool when it is finished with it. Centralized configuration of IP addresses. The system manager can easily setup IP addresses to nodes from the central IP granting server. Barring computers from connecting to a network. Some networks are set up so that they must get a valid IP address before they can connect to the network (typically in Unix-type networks). The IP granting server will check the MAC address of the requester, if it is not allowed the server will not grant it an IP address.

35 University Author: W.Buchanan. IP The Address (35) Computer Computer Studies Studies Router Router Mechanical Mechanical Department Department Gateway Gateway Router Router Internet Electrical Electrical Department Department Router Router

36 Example network Token Ring networks Mimas Mwave Moon Oberon HP Dione Pluto Venus Mercury Saturn Titan Io Earth Rhea Ariel Neptune Phobos +Demos +Uranus Intel VAX Leda Castor Miranda Triton pc pc3 PC Ethernet network Pollux Vega(X) Spica Rigel(X) Workstation Ethernet network eepc01 eepc02 Author: W.Buchanan. IP The Address (36)

37 Author: W.Buchanan. IP The Address (37) MAC1, IP1 [IP address] [Subnet mask] [Gateway is the port of the router] [IP address] [Subnet mask] [IP address] [Subnet mask]

38 Author: W.Buchanan. IP The Address (38)

39 IPCONFIG /ALL Author: W.Buchanan. IP The Address (39) Ethernet adapter Local Area Connection 3: Connection-specific DNS Suffix. : myuni.ac.uk Description : Realtek RTL8139/810x Family Physical Address : 00-0A-E4-01-2C-F1 Dhcp Enabled : Yes Autoconfiguration Enabled.... : Yes IP Address : Subnet Mask : Default Gateway : DHCP Server : DNS Servers : Primary WINS Server : Secondary WINS Server : Lease Obtained : 05 November :19:35 Lease Expires : 08 November :19:35

40 Author: W.Buchanan. IP The Address (40) Here s my MAC address. What s my IP address? Here it is DHCP server What s the IP address for this site? Here it is DNS server Here s my Windows name. Can I have an IP address? Here it is WINS server

41 address translation Author: W.Buchanan. IP The Address (41) IP IP Src: Src: IP IP Dest: Dest: Outgoing data data NAT NAT Router Router IP IP Src: Src: IP IP Dest: Dest: Outgoing data data IP IP Src: Src: IP IP Dest: Dest: Incoming data data IP IP Src: Src: IP IP Dest: Dest: Incoming data data PAT (Port address translation) Maps many addresses to one global address.

42 NAT The advantages Author: W.Buchanan. IP The Address (42) Increases range of address. Hides the network address of the network. Allow easy creation of subnetworks. can use their own network addresses, such as as , , and so so on. NAT Global addresses (which are unique on the Internet)

43 Borrowing addresses for some links Author: W.Buchanan. IP The Address (43) E0 IP address unnumbered borrows addresses from another port E0 Router Router Router A Router S0 S0 B E1 E1