Title: Internet Addresses
1Internet Addresses
2TCP/IP Layers
Application
Telnet
FTP
SMTP
SNMP
Transport
TCP
UDP
Internet
IP
ICMP
ARP
Network Interface
Ethernet, FDDI, ATM, Frame Relay
Hardware
Wire, Coax, Fiber optic, Satellite
3Universal Identifiers
- Universal Communication Service
- Allows any host to communicate with any other
host - Host must have unique identifier
- Host identifiers
- Names
- Addresses
- Routes
4Universal Identifiers
- Frasch Hall
- 201 South Grant Avenue
- Route
- 71 South to Broad Street Exit
- West on Broad Street
- South on Grant
- Right on Rich Street
- Right into parking lot
5Universal Identifiers
- Why not use MAC address as universal identifier?
- May not be unique (depends on network technology)
- Need to route message to host
- Use phone number as address
6Internet Addresses
- Each host on a TCP/IP internet is assigned a
unique 32 bit internet address that is used in
all communication with that host - Three primary classes (two other)
- Pair consisting of (network, host)
- Easy (quick) to extract network id for routing
7TCP/IP Model Boundaries
- Application program as well as all protocol
software from the Internet layer upward use only
IP addresses the network interface layer handles
physical addresses
8TCP/IP Model Boundaries
Application
Transport
Internet
IP Address
Network Interface
MAC (Hardware) Address
Hardware
9Internet Addresses
- Two parts to identify address
- Routing only cares about network part
Network
Host
10Class A Address
- 8 bit network id
- 24 bit host id
- Also called /8 address
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
Network
0
Host
11Class B Address
- 16 bit network id
- 16 bit host id
- Also called a /16 address
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
Network
10
Host
12Class C Address
- 24 bit network id
- 8 bit host id
- Also called a /24 address
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
Network
110
Host
13Class D address
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
Multicast
1110
14Class E Address
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
Reserved for future use
11110
15Network Size Limitations
16Dotted Decimal Notation
- 32 Bit strings of 0s and 1s difficult to read
- Four decimal integers separated by dots
- 11000000 01000110 11111100 00001000
- 192.70.252.8
17Address Ranges
- Class A
- 1.0.0.0 to 126.255.255.255
- Class B
- 128.0.0.0 to 191.255.255.255
- Class C
- 192.0.0.0 to 223.255.255.255
18Special Addresses
- Class A
- Netid 0 reserved for default route
- 0.0.0.0
- Netid 127 reserved for loop-back
- 127.x.x.x
19Loop-back Address
- Address of 127.x.x.x
- Often 127.0.0.1
- Used to test TCP/IP on a machine
- Does not access network
20Network Addresses
- Network id ? 0 and Host id 0 refers to network
- e.g.
- 10.0.0.0
- 129.42.0.0
- 192.70.252.0
Network
000. . . . 000
21Directed Broadcast
- Host id of all 1s is directed broadcast
- For example
- 10.255.255.255
- 129.42.255.255
- 192.70.252.255
- Maps to physical broadcast when possible
Network
111. . . . 111
22Limited Broadcast
- Address of all 1s (net and host)
- Used during startup when dont know who to talk
to - e.g. 255.255.255.255
111. . . . 111
111. . . . 111
23Subnet Addressing
- Use part of host id as sub-net identifier
- More in Chapter 10
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
Network
10
Host
Subnet
24Multi-homed Hosts
- Host may have two or more connections
- IP address specifies a connection to a network
- Physical connection to N networks requires N
IP addresses
Host
Network B
Network A
192.70.252.0
199.218.4.0
25Weakness in Addressing
- If number of hosts outgrows class, all hosts must
get new addresses - If a host moves to a different network, it must
get a new IP address - Route taken depends on IP address
- Multi-homed hosts can cause problems
26Multi-homed host problem
- Two hosts - one multi-homed
- One router
I1
I2
I3
Host A
Host B
Router
I4
I5
27Internet Addressing Authority
- Until 1998 Internet Assigned Number Authority
(IANA) - After Jon Postels death, Internet Corporation
For Assigned Names and Numbers (ICANN) - Asian Pacific Network Information Centre (APNIC)
- American Registry for Internet Number (ARIN)
- Réseaux IP Européens (RIPE NCC)
28Internet Addressing Authority
- Usually the ISP assigns address
- Assigns IP network addresses
- Site assigns host ids
- Only if connected to global Internet
29Reserved Addresses
- A set of prefixes reserved for private networks
- Non-routable addresses
- 10.x.x.x
- 172.16.x.x
- 192.168.x.x
- 169.254.x.x
30Network Example
Router
65
192.70.252.0
8
6
125
35
Einstein
Euler
Linnaeus
Freud
31Network Byte Order
- Machines store numbers differently
- Little Endian
- Big Endian
104
103
102
101
101
102
103
104
100
Memory
101
102
103
104
105
32Network Byte Order
- TCP/IP network standard byte order
- Big Endian