Chap3. i pv4
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This document discusses IPv4 addressing concepts including: - ARP and gratuitous ARP for address resolution and conflict detection - Bitwise operations on IPv4 addresses like NOT, AND, OR - Classful addressing which divides IPv4 space into classes A, B, C, D, E and uses network masks - Classless addressing with CIDR which allows variable length network prefixes - Special IPv4 addresses like network, broadcast and private addresses
Chap3. i pv4
- 1. Lesson 3 IPv4 Yuan Application Engineer / iConnectivity Group (ICG) 2014.11.24 1
- 2. Recap ARP 2
- 3. Application • ARP probe – an ARP request constructed with an all-zero sender IP address – used in the IPv4 Address Conflict Detection specification (RFC 5227) – Sent when there is any change in connectivity – Should not send periodically 5
- 4. Application • ARP Announcements (gratuitous ARP) – Updating other host's mapping of a hardware address when the sender's IP address or MAC address has changed – Broadcast as an ARP request containing the sender's protocol address (SPA) in the target field (TPA=SPA), with the target hardware address (THA) set to zero. – detecting IP conflicts – No ARP reply is expected 6
- 5. Hands On • ARP probe • Gratuitous ARP 7
- 6. IPv4 8
- 7. Outline • IPv4 – Overview – Bitwise operation – Classful Addressing – Classless Addressing – Special Addresses – NAT 9
- 8. Overview • Internet Protocol version 4 – The fourth version in the development of the Internet Protocol (IP) Internet – IPv4 is described in IETF publication RFC 791 (September 1981), replacing an earlier definition (RFC 760, January 1980) • Addressing – 32-bit(4-byte) – Address space to 232 addresses 10
- 9. Bitwise operation • Bitwise NOT – unary, complenent 11 32 bits NOT 32 bits input output input output 0 1 1 0 ordinary 00010001 01111001 00001110 00100011 complement 11101110 10000110 11110001 11011100 ordinary 17 121 14 35 complement 238 134 241 220 Base-2 Base-10
- 10. Bitwise operation • Bitwise NOT – unary, complenent – Hands on a. 00011001 00001101 00101001 11100110 12 32 bits NOT 32 bits input output input output 0 1 1 0 a. 11100110 11110010 11010110 00011001 b. 17.63.110.114 b. 238.192.145.141
- 11. Bitwise operation • Bitwise AND – binary, pick the lower 32 bits 13 AND 32 bits input 1 output input 1 Input 2 output 0 0 0 0 1 0 1 0 0 1 1 1 input 1 00010001 01111001 00001110 00100011 input 2 11111111 11111111 10001100 00000000 output 00010001 01111001 00001100 00000000 input 1 17 121 14 35 input 2 255 255 140 0 output 17 121 12 0 Base-2 Base-10 32 bits input 2
- 12. Bitwise operation • Bitwise AND – binary, pick the lower 32 bits a. 11000000 00010010 00010010 00001000 14 AND 32 bits input 1 output 32 bits input 2 input 1 Input 2 output 0 0 0 0 1 0 1 0 0 1 1 1 a. 11100110 11110010 11010110 00011001 11011000 00011111 00110011 11001000 b. 17.63.110.114 255.112.0.1 b. 17.32.0.0
- 13. Bitwise operation • Bitwise OR – binary, pick the higher 32 bits 15 OR 32 bits input 1 output input 1 Input 2 output 0 0 0 0 1 1 1 0 1 1 1 1 input 1 00010001 01111001 00001110 00100011 input 2 11111111 11111111 10001100 00000000 output 11111111 11111111 10001110 00100011 input 1 17 121 14 35 input 2 255 255 140 0 output 255 255 142 35 Base-2 Base-10 32 bits input 2
- 14. Bitwise operation • Bitwise OR – binary, pick the higher 32 bits a. 11111110 11111111 11110111 11011001 16 OR 32 bits input 1 output 32 bits input 2 input 1 Input 2 output 0 0 0 0 1 1 1 0 1 1 1 1 a. 11100110 11110010 11010110 00011001 11011000 00011111 00110011 11001000 b. 17.63.110.114 255.112.0.1 b. 255.127.110.115
- 15. Classful Addressing • Divides into 5 classes 1 1 1 1 0 0 0 0 Class A: 231= 2,147,483,648 addresses, 50% Class B: 230= 1,073,741,824 addresses, 25% Class C: 229= 536,870,912 addresses, 12.5% Class D: 228= 268,435,456 addresses, 6.25% Class E: 228= 268,435,456 addresses, 6.25% 17 8 bits 8 bits 8 bits 8 bits Class A 0……. Class B 10…… Class C 110….. Class D 1110…. Class E 1111…. 8 bits 8 bits 8 bits 8 bits Class A 0-127 Class B 128-191 Class C 192-223 Class D 224-239 Class E 240-255 Class A Class B Class C Class D Class E
- 16. Classful Addressing • Two-level addressing – netid, hostid, like Tel: (02)2792-7818 – Network address 8 bits 8 bits 8 bits 8 bits Class A netid hostid 128 nets, 16,777,214 hosts per net Class B netid hostid 16,384 nets, 65,534 host per net Class C netid hostid 2,097,152 nets, 254 host per net Class D Multicast address Class E Reserve 18
- 17. Classful Addressing – network mask(default mask) 8 bits 8 bits 8 bits 8 bits Network mask Class A 11111111 00000000 00000000 00000000 255.0.0.0 Class B 11111111 11111111 00000000 00000000 255.255.0.0 Class C 11111111 11111111 11111111 00000000 255.255.255.0 destn addr. input 1 201 24 67 32 network mask input 2 255 255 0 0 Output AND 201 24 0 0 19
- 18. Classful Addressing • Three-level addressing – Subnetting • Network address, subnet address, host address, like Tel: (02)2792-7818 Class B 10101000 01011111 00000000 00000000 (168.95.0.0) 10101000 01011111 00000000 00000000 (168.95.0.0) 20 network address network address host address host address subnet address
- 19. Classful Addressing – subnet mask 8 bits 8 bits 8 bits 8 bits Class B 10101000 01011111 11000000 00000001 168.95.192.1 Network mask 11111111 11111111 00000000 00000000 255.255.0.0 Subnet mask 11111111 11111111 11111000 00000000 255.255.248.0 destn addr. input 1 141 14 120 77 subnet mask input 2 255 255 192 0 21 Output AND 141 14 64 0
- 20. Classful Addressing • Three-level addressing – Supernetting Class C 11101000 01011111 00111000 00000000 (232.95.56.0) 11101000 01011111 00111000 00000000 subnetting 22 network address network address host address host address 11101000 01011111 00111000 00000000 supernetting network address host address
- 21. Classful Addressing – supernet mask 8 bits 8 bits 8 bits 8 bits Class C 11101000 01011111 00111010 00000001 235.95.58.1 Network mask 11111111 11111111 11111111 00000000 255.255.255.0 Supernet mask 11111111 11111111 11111000 00000000 255.255.248.0 destn addr. input 1 141 14 120 77 subnet mask input 2 255 255 192 0 23 Output AND 141 14 64 0
- 22. Classful Addressing – network mask – subnet mask – supernet mask 8 bits 8 bits 8 bits 8 bits Class C 11101000 01011111 00111010 00000001 235.95.58.1 supernet mask 11111111 11111111 11111000 00000000 255.255.248.0 network mask 11111111 11111111 11111111 00000000 255.255.255.0 subnet mask 11111111 11111111 11111111 11100000 255.255.255.224 24
- 23. Classful Addressing • Class 4 -IP multicast addressing – the address denotes the recipient group – no geographic or location boundaries Class D Multicast Address Allocations by IANA Description IPv4 Address Range Local-link address (reserved) 224.0.0.0/24 Globally scope address (assigned) 224.0.1.0 to 238.255.255.255 25 Administratively scoped addresses (local) 239.0.0.0/8
- 24. Classless Addressing • Classful addressing, the network portion ends on one of the separating dots in the address • Classless addressing uses a variable number of bits for the network and host portions of the address 26 …… …… …… …… Address Space Address Space Blocks of same size Blocks of different sizes
- 25. Classless Addressing • Prefix: internet, like netid • Suffix: host, like hostid netid Classful addressing 11101000 01011111 00111000 00000000 Classless addressing 11101000 01 011111 00111000 00000000 27 prefix hostid suffix
- 26. Classless Addressing • CIDR, classless interdomain routing, slash notation byte . byte . byte . byte / n=prefix length Slash notation Network mask 230.8.24.56/16 block 230.8.0.0 to 230.8.255.255 255.255.0.0 230.8.24.56/20 block 230.8.16.0 to 230.8.31.255 255.255.240.0 230.8.24.56/26 block 230.8.24.0 to 230.8.24.63 255.255.255.192 230.8.24.56/27 block 230.8.24.32 to 230.8.24.63 255.255.255.224 230.8.24.56/29 block 230.8.24.56 to 230.8.24.63 255.255.255.248 28 Classful addressing Level Prefix length A /8 B /16 C /24 D /4 E /4
- 27. Special Addresses • This network: host ID all zero – 203.75.205.0, this class C network • Broadcast: host ID all one, also use in subnet – 203.75.205.255, broadcast in 203.74.205.0 • Limit(Local) broadcast: broadcast in local network – 255.255.255.255, broadcast in the same network • Private IP address Private IP Class A 10.0.0.0 – 10.255.255.255 Class B 172.16.0.0 – 172.31.255.255 Class C 192.168.0.0 – 192.168.255.255 29
- 28. Special Addresses Reserved address blocks Range Description Reference 0.0.0.0/8 Current network (only valid as source address) RFC 6890 10.0.0.0/8 Private network RFC 1918 100.64.0.0/10 Shared Address Space RFC 6598 127.0.0.0/8 Loopback RFC 6890 169.254.0.0/16 Link-local RFC 3927 172.16.0.0/12 Private network RFC 1918 192.0.0.0/24 IETF Protocol Assignments RFC 6890 192.0.2.0/24 TEST-NET-1, documentation and examples RFC 5737 192.88.99.0/24 IPv6 to IPv4 relay RFC 3068 192.168.0.0/16 Private network RFC 1918 198.18.0.0/15 Network benchmark tests RFC 2544 198.51.100.0/24 TEST-NET-2, documentation and examples RFC 5737 203.0.113.0/24 TEST-NET-3, documentation and examples RFC 5737 224.0.0.0/4 IP multicast (former Class D network) RFC 5771 240.0.0.0/4 Reserved (former Class E network) RFC 1700 255.255.255.255 Broadcast RFC 919 30
- 29. Thanks 31
Editor's Notes
- #26: Local-link address TTL=1 campus