IP Address Sirak Kaewjamnong 1 Three Level of

IP Address Sirak Kaewjamnong 1

Three Level of Address • Host name – ratree. psu. ac. th • Internet IP address – 192. 168. 100. 3 32)bits address with “dot-decimal” notation( • Station address : Hardware address assigned to network interface card, refer to MAC address or Ethernet Address (48 bits( – 00: 5 c: f 0: 3 b: 00: 4 a 2

Converting Host Name to MAC Address cs 05. cs. psu. ac. th 172. 28. 80. 96 00: 50: ba: 49: 9 d: b 9 Resolve IP address by Domain Name System(DNS) Resolve MAC address by Address Resolution Protocol(ARP) 3

IP Address with Router IP address associated with interface 172. 28. 80. 15 172. 28. 80. 16 172. 28. 85. 120 (not machine) • Each interface has its own IP address 172. 28. 85. 1 • Machine with more than one 172. 28. 80. 1 192. 168. 99. 39 interface called multi-home Internet • Router is multi-homed machine 192. 168. 98. 11 • Multi-homed not to be router 192. 168. 100. 4 192. 168. 100. 3 192. 168. 100. 1 4

Addressing Concept • Partitions address into 2 fields * network address * node address 5

IP Address 32 bits 8, 16, 24 bits Network Host 32 bits 8 bits 172 28 80 10101100 00011100 01010000 . . . 8 bits 96 01100000 6

IP Address Class 32 bits address length, contain 2 parts • Network identifier • Host identifier Class A Class B Class C Class D 8 16 24 0 Network ID Host ID 110 Network ID Host ID 1110 Multicast Address Class E 11110 32 Unused 7

IP Address Class Initial Bit Class bits net host A B C D E 0 10 1110 11110 7 14 21 28 27 24 16 8 - range address spaces usable 0. 0 -127. 255 224 16, 677, 214 128. 0. 0. 0 -191. 255 216 65, 534 192. 0. 0. 0 -223. 255 28 254 224. 0. 0. 0 -239. 255 240. 0 -247. 255 8

Special Address • Host ID “all 0 s” is reserved to refer to network number – 18. 0. 0. 0 , 158. 108. 0. 0 , 192. 168. 100. 0 • Host ID “all 1 s” is reserved to broadcast to all hosts on a specific network – 18. 255 , 158. 108. 255 , 192. 168 • Address 0. 0 means “default route” • Address 127. 0. 0. 0 means “this node” (local loopback). Message sent to this address will never leave the local host • Address 255 is reserve to broadcast to every host on the local network (limited broadcast( 9

Private Address Reserve for Intranet or private network • 10. 0 – 10. 255 (1 class A ) • 172. 16. 0. 0 – 172. 31. 255 (16 class B) • 192. 168. 0. 0 – 192. 128. 255 (256 class C) 10

Problem with Class Assignment • Class A takes 50 % range • Class B takes 25 % range • Class C take 12. 5 % range These leads to: • address wasteful (specially in class A) • running out of IP address Class A Class B E D C 11

How to assigns IP Address (RFC 1466) • Class A : no allocations will be made at this time • Class B: allocations will be restricted. To apply: – organization presents a subnetting more than 32 subnets – organization more than 4096 hosts • class C: divided into allocated block to distributed reginal 12

Class C Assignment • Assignment is based on the subscriber ‘s 24 month projection according to the criteria: . 1 Requires fewer than 256 addresses : 1 class C network. 2 Requires fewer than 512 addresses : 2 contiguous class C networks. 3 Requires fewer than 1024 addresses : 4 contiguous class C networks. 4 Requires fewer than 2048 addresses : 8 contiguous class C networks. 5 Requires fewer than 4096 addresses : 16 contiguous class C networks. 6 Requires fewer than 8192 addresses : 32 contiguous class C networks. 7 Requires fewer than 16384 addresses : 64 contiguous class C networks 13

Problem with Large Network • Class B “Flat Network” more than 60, 000 hosts – How to manage? – Performance? 150. 0. 0. 1 150. 0. 0. 2 . . . 150. 0. 255. 254 14

Problem with Large Network • Class B “subdivided network” to smaller group with router 150. 0. 1. 1 150. 0. 40. 2 150. 0. 10. 1 150. 0. 10. 2 Router 150. 0. 200. 1 150. 0. 200. 2 15

Subnetwork Benefits • • Increase the network manager’s control the address space Easy to allocate the address space Better network performance Hide routing structure from remote routers, thus reducing routes in their routing tables • Subdivide on IP network number is an important initial task of network managers 16

How to assign subnet • Divide host ID into 2 pieces host ID Network ID Subnet address Host address Choose appropriate size • Class B address such as 150. 0 might use its third byte to identify subnet – subnet 1 150. 0. 1. X X = host address range from 1 -254 – subnet 2 150. 0. 200. X 17

Subnet Mask • 32 bit number, tell router to recognize the subnet field, call subnet mask • subnet rule: The bit covering the network and subnet part of address are set to 1 • Example class B with 24 bits mask 1111 1111 0000 subnet mask = 255. 0 * zero bit are used to mask out the host number resulting the network address 18

Subnet Mask Subnet mask 255. 0 for class B tells: • network has been partition to 254 subnets. 150. 1 X to 150. 10. 254. X • logic “and” between IP address with mask yields network address 150. 10. 243150. 1. 55 and 255. 0255. 0. 150. 101. 0 150. 10. 240. 0 19

Subnet Mask Bits Use contiguous subnet mask 128 1 1 1 1 64 0 1 1 1 1 32 0 0 1 1 1 16 0 0 0 1 1 1 8 0 0 1 1 4 0 0 0 1 1 1 2 0 0 0 1 1 1 0 0 0 0 1 = 128 = 192 = 224 = 240 = 248 = 252 = 254 = 255 20

Subnet Class B Example • 255. 0. 0 (0000 0000) 0 subnet with 65534 hosts (default subnet) • 255. 192. 0 (1100 0000) 2 subnets with 16382 hosts • 255. 252. 0 (1111 1100 0000) 62 subnets with 1022 hosts • 255. 0 (1111 0000) 254 subnets with 254 hosts • 255. 252 (1111 11000) 16382 subnets with 2 hosts 21

Subnet Class C Example • 255. 0 ( 0000) 0 subnets with 254 hosts (default subnet) • 255. 192 (1100 0000) 2 subnets with 62 hosts • 255. 224 (1110 0000) 6 subnets with 30 hosts • 255. 240 (1111 0000) 14 subnets with 14 hosts 22

Subnet Interpretation IP Address 158. 108. 2. 71 150. 10. 25. 3 130. 122. 34. 132 200. 190. 155. 66 18. 20. 15. 2 Subnet mask 255. 0 255. 192 255. 0. 0 Interpretation host 71 on subnet 158. 108. 2. 0 host 3 on subnet 150. 10. 25. 0 host 4 on subnet 130. 122. 34. 128 host 2 on subnet 200. 190. 155. 64 host 15. 2 on subnet 18. 20. 0. 0 23

Class B Subnet with Router is used to separate network Picture from Kasetsart University 24

Subnet Routing Traffic is route to a host by looking “bit wise AND” results if dest IP addr & subnet mask = = my IP addr & subnet mask send packet on local network { dest IP addr is on the same subnet{ else send packet to router {dest IP address is on difference subnet{ 25

Type of Subnet • Static subnet: all subnets in the subnetted network use the same subnet mask – pros: simply to implement, easy to maintain – cons: wasted address space (consider a network of 4 hosts with 255. 0 wastes 250 IPs) • Variable Length Subnet : the subnets may use difference subnet masks – pros: utilize address space – cons: required well managment 26

Variable Length Subnet Mask • General idea of VLSM – A small subnet with only a few hosts needs a subnet mask that accommodate only few hosts – A subnet with many hosts need a subnet mask to accomdate the large number of hosts • Network Manager’s responsibility to design and appropriate VLSM 27

VLSM Sample Case Picture from Kasetsart university 28

CIDR Classless Inter-Domain Routing 29

Address Allocation Problem • Exhaustion of the class B network address space • The lack of a network class of size which is appropriate for mid-sizes organization – class C, with a max of 254 hosts, too small – While class B, with a max of 65534 hosts, too large • Allocate block of class C instead and downside is more routes entry in routing table 30

Routing Table Problems • Issue multiple block class C addresses (instead single class B address) solves a running out of class B address • Introduces problems of routing table – By default, a routing table contains an entry for every network – How large a routing table should be for all class C networks? • Growth of routing table in the internet routers beyond the ability of current software and hardware manage 31

Size of the Routing Table at the core of the Internet Source: http: //www. telstra. net/ops/bgptable. html 32

Prefix Length Distribution 70000 60000 50000 Number of Prefixes 40000 30000 20000 10000 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 32 Prefix Length Source: Geoff Huston, Oct 2001 33

How to solve • Topological allocate IP address assignment • We divide the world into 8 regions (RFC 1466) Multi regional 192. 0. 0. 0 - 193. 255 Europe 194. 0. 0. 0 - 195. 255 Others 196. 0. 0. 0 - 197. 255 North America 198. 0. 0. 0 - 199. 255 Central/South America 200. 0 - 201. 255 Pacific Rim 202. 0. 0. 0 - 203. 255 Others 204. 0. 0. 0 - 205. 255 Others 206. 0. 0. 0 - 207. 255 IANA Reserved 208. 0. 0. 0 - 223. 255 34

Classless Interdomain Routing • Class C address’s concept becomes meaningless on these route between domain, the technique is call Classless Interdomain Routing or CIDR or Supernet • Kay concepts is to allocate multiple IP address in the way that allow summarization into a smaller number of routing table (route aggregate( • CIDR is supported by BGP 4 and based on route aggregation – 16 class C addresses can be summarized to a single routing entry (router can hold a single route entry for a main trunks between these areas( 35

Supernetting • An organization has been allocate a block of class C address in 2 n with contiguous address space – archive by using bits which belongs to the network address as hosts bits – class C example : altering the default class C subnet mask such that some bit change from 1 to 0 (Super) netmask 4 class C networks appear 1111111100 0000 to network outside as a single network 255. 252. 0 36

Supernetting Sample • An organization with 4 class C 193. 0. 35. 0 , 193. 0. 34. 0 , 193. 0. 33. 0 , 193. 0. 3 0000 0011111111 mask 255 00001000 0000 11000001 net 193. 0. 3 0000 01001000 0000 11000001 net 193. 0. 3 0000 11001000 0000 11000001 net 193. 0. 3 Bit wise AND results 193. 0. 32. 0: 11000001 0000 00100000 • This organization’s network has changed from 4 net to a single net with 1, 022 hosts 37

The longest Match Supernetting • Europe has 194. 0. 0. 0 - 195. 255 with mask 254. 0. 0. 0 • A case of one organization (195. 0. 16. 0 - 195. 0. 36. 0 mask 255. 254. 0) needs different routing entry • datagrams 195. 0. 20. 1 matches both Europe’s and this organization. How to do? • Routing mechanism selects the longest mask (255. 254. 0 is longer than 254. 0. 0. 0), then route to the organization 38

Summary • Routing decisions are now made based on masking operations of the entries 32 bits address, hence the term “classes” • No existing routes is changed • CIDR slows down the growth of routing tables (current 130 K entries in core routers) • Short term solution to solve routing problem • limitation: not all host/router software allows supernet mask 39

IPv 6 40

IPv 4’s Limitations • • Two driving factors : addressing and routing Addressing : address depletion concerns – Internet exhaust the IPv 4 address space between 2005 and 2011 [RFC 1752]. Routing : routing table explosion – Currently ~120 K entries in core router More factors. . . – Opportunity to optimized on many years of deployment experience – New features needed : multimedia, security, mobile, etc. . 41

Key Issues The new protocol MUST • Support large global internetworks • A clear way to transition IPv 4 based networks 42

What is IPv 6? • IPv 6 is short for "Internet Protocol Version 6. " • IPv 6 is the "next generation" protocol designed by the IETF to replace the current version Internet Protocol, IP Version 4 43

IPV 6 Key Advantages • • 128 bit fix length IP address Real time support Self-configuration of workstations or auto configuration Security features Support mobile workstations Protocol remains the same principle IPv 4 compatibility 44

IPV 6 Address Representation • l l Hexadecimal values of the eight 16 -bit pieces x: x: x Example FEDC: BA 98: 7654: 3210: FEDC: BA 98: 7654: 3210 1080: 0: 8: 800: 200 C: 417 A Compressed form: ": : " indicates multiple groups of 16 -bits of zeros. 1080: 0: 8: 800: 200 C: 417 A 1080: : 8: 800: 200 C: 417 A FF 01: 0: 0: 0: 101 FF 01: : 101 0: 0: 1 : : 1 45 0: 0: 0 : :

IPV 6 Address Representation(cont) • Mixed environment of IPv 4 and IPv 6 address IPv 4 -compatible IPv 6 address technique for hosts and routers to dynamically tunnel IPv 6 packets over IPv 4 routing infrastructure 0: 0: 0: 13. 1. 68. 3 => : : 13. 1. 68. 3 IPv 4 -mapped IPv 6 address represent the addresses of IPv 4 -only nodes (those that do not support IPv 6) as IPv 6 addresses IPv 4 -only IPv 6 -compatible addresses are sometimes used/shown for sockets created by an IPv 6 -enabled daemon, but only binding to an IPv 4 address. These addresses are defined with a special prefix of length 96 (a. b. c. d is the IPv 4 address): 0: 0: 0: FFFF: 129. 144. 52. 38/96 => : : FFFF: 129. 144. 52. 38/96 http: //www. tldp. org/HOWTO/Linux+IPv 6 -HOWTO/x 324. html 46

Format Prefix • Format Prefix : – Leading bits indicate specific type of an IPv 6 address – The variable-length field – Represented by the notation: IPv 6 -address/prefix-length Example : the 60 -bit prefix 12 AB 0000 CD 3 12 AB: 0000: CD 30: 0000: 0000/60 12 AB: : CD 30: 0: 0/60 12 AB: 0: 0: CD 30: : /60 47

Type of Addresses Three type of addresses • UNICAST : defines a single interface A packet sent to a unicast address is delivered to the interface identified by that address. • ANYCAST : defines a set of interfaces A packet sent to an anycast address is delivered to one of the interfaces • MULTICAST : defines a set of interfaces A packet sent to a multicast address is delivered to all interfaces identified by that address 48

Address Types • Unspecified address, 0: 0: 0 or : : • Loopback address, 0: 0: 1 of : : 1 • Global address, 2000: : /3 and E 000: : /3 currently only 2000: : /3 is being assigned • Link local address, FE 80: : /64 • Site local address, FEC 0: : /10 49

IPV 6 Address Allocation 50

Address Registries Address registries for IPv 6 are the same one as for IPv 4, ARIN, RIPE and APNIC. • Only large network providers will ever obtain addresses directly from the registries, such as UNINET : one such provider in Thailand • If a /35 prefix is allocates, the registry internally will reserve a /32. • The basic unit of assignment to any organization is a /48 prefix 51

Aggregatable Unicast Address Three level hierarchy: • Public Topology : providers and exchanges who provide public Internet transit services (P 1, P 2, P 3, P 4, X 1, X 2, P 5 and P 6) • Interface Identifier: interfaces on links x 2 X 1 P 2 S 1 • Site Topology : does not provide public transit service to nodes outside of the site (S 1, S 2, S 3, S 4, S 5 and S 6) P 3 P 1 P 4 S 2 P 5 S 4 S 5 P 6 S 3 S 6 52

Aggregatable Unicast Address 3 13 8 24 FP TLA ID RES NLA ID Public Topology FP=Format Prefix= 001 TLA= Top Level Aggregation RES= Reserved NLA=Next-Level Aggregation SLA=Site-Level Aggregation 16 SLA ID 64 bits Interface ID Site Topology Interface Identifier 53

Header Comparison 0 15 16 vers hlen 20 bytes TOS • flags protocol frag offset header checksum source address destination address • options and padding pay load length 40 bytes flow label next header hop limit • source address Added: (2) – Traffic class – flow label destination address IPv 6 Changed: (3) – total length=> payload – protocol => next header – TTL=> hop limit IPv 4 vers traffic class Removed (6) – ID, Flags, frag offset – TOS, hlen – header checksum total length identification TTL 31 • Expanded – address 32 bits to 128 bits 54

IPv 6 Node Configuration • Ethernet address is an IEEE EUI-48 • Node address is an IEEE EUI-64 • EUI-48 can be converted into an EUI-64 by inserting the bits FF FE between the 3 rd and 4 th octets EUI-48 EUI-64 00: 06: 5 B: DA: 45: AD = 00: 06: 5 B: FF: FE: DA: 45: AD 55

Auto configuration “Plug and play” feature • Stateless mode : via ICMP (no server required) Prefix 4 c 00: : /80 Link Address 00: A 0: C 9: 1 E: A 5: B 6 IPv 6 Address 4 c 00: : A 0: C 9 FF: EF 1 E: A 5 B 6 Router adv. • Stateful server mode : via DHCP 00: A 0: C 9: 1 E: A 5: B 6 DHCP server DHCP request DHCP response 4 c 00: : A 0: C 9 FF: FE 1 E: A 5 B 6 56

Security • • Authentication/Confidential Authentication: – MD 5 based • Confidential : – payload encryption – Cipher Block Chaining mode of the Data Encryption Standard (DESCBC) 57

Support Protocols • • ICMPv 6 [RFC 1885] DHCPv 6 DNS extensions to support IPv 6 [RFC 1886] Routing Protocols – – – RIPv 6 [RFC 2080] OSPFv 6 IDRP IS-IS Cisco EIGRP 58

Dual Stack • • Dual stack hosts support both IPv 4 and IPv 6 Determine stack via DNS Application TCP IPv 6 IPv 4 Ethernet IPV 6 Dual stack host IPv 4 59

Tunneling: automatic tunneling • • Encapsulate IPv 6 packet in IPv 4 Rely on IPv 4 -compatible IPv 6 address IPv 6 host : : 1. 2. 3. 4 IPv 4 Network R 1 flow label payload len next hops src = : : 1. 2. 3. 4 (IPv 4 -compatible IPv 6 adr) dst = : : 2. 3. 4. 5 (IPv 4 -compatible IPv 6 adr) payload 2. 3. 4. 5 : : 2. 3. 4. 5 6 traffic IPv 4/6 host 2. 3. 4. 5 R 2 4 hl TOS frag id len frag ofs 4 hl TOS frag id prot checksum src: 1. 2. 3. 4 dst: 2. 3. 4. 5 6 traffic flow label TTL payload len TTL next hops len frag ofs prot checksum src: 1. 2. 3. 4 dst: 2. 3. 4. 5 6 traffic flow label next hops src = : : 1. 2. 3. 4 (IPv 4 -compatible IPv 6 adr) dst = : : 2. 3. 4. 5 (IPv 4 -compatible IPv 6 adr) dest = : : 2. 3. 4. 5 (IPv 4 -compatible IPv 6 adr) payload 60

Tunneling : configured tunneling • • Encapsulate IPv 6 packet in IPv 4 Rely on IPv 6 -only address IPv 6 address (IPv 4 -compatible address are unavailable) IPv 6 host : : 1: 2: 3: 4 R 1 flow label payload len next hops R 2 : : 2: 3: 4: 5 6 traffic IPv 6 host : : 2: 3: 4: 5 IPv 4 Network 4 hl TOS frag id len frag ofs TTL src = : : 1: 2: 3: 4 (IPv 6 adr) dst = : : 2: 3: 4: 5 (IPv 6 adr) payload prot checksum src = R 1 dst =R 2 6 traffic flow label payload len next src =: : 1: 2: 3: 4 (IPv 6 adr) hops 6 traffic flow label payload len next hops src = : : 1: 2: 3: 4 (IPv 6 adr) dst = : : 2: 3: 4: 5 (IPv 6 adr) payload 61

Header Translation l l l Full IPv 6 system need to support few IPv 4 -only systems rely on IPv 6 host : : 1: 2: 3: 4 IPv 4 -mapped R 1 IPv 6 address : : 2: 3: 4: 5 IPv 4 host 2. 3. 4. 5 IPv 6 Network R 2 2. 3. 4. 5 : : 2. 3. 4. 5 6 traffic flow label payload len next src = : : 1: 2: 3: 4 (IPv 6 adr) dst = : : 2. 3. 4. 5 (IPv 6 adr) payload hops src = : : 1: 2: 3: 4 (IPv 6 adr) dst = : : 2. 3. 4. 5 (IPv 6 adr) hops 4 hl TOS frag id TTL len frag ofs prot checksum src = R 1 dst =R 2 payload 62

Migration Steps 1. Upgrade DNS servers to handle IPv 6 Address 2. Introduce dual stack systems that support IPv 4 and IPv 6 3. Rely on tunnels to connect IPv 6 networks separated by IPv 4 networks 4. Remove support for IPv 4 5. Rely on header translation for IPv 4 -only systems 63

Conclusion • • IPv 6 will provide for future Internet growth and enhancement IPv 6 : – solve the Internet scaling problem – support large hierarchical address – provide a flexible transition mechanism – interoperate with IPv 4 – provide a platform for new Internet functionality 64