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IP Address

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  1. IP Address Sirak Kaewjamnong

  2. 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) • 00:5c:f0:3b:00:4a

  3. cs05.cs.psu.ac.th 172.28.80.96 00:50:ba:49:9d:b9 Resolve IP address by Domain Name System(DNS) Resolve MAC address by Address Resolution Protocol(ARP) Converting Host Name to MAC Address

  4. IP address associated with interface (not machine) Each interface has its own IP address Machine with more than one interface called multi-home Router is multi-homed machine Multi-homed not to be router IP Address with Router 172.28.80.15 172.28.80.16 172.28.85.116 172.28.85.120 172.28.85.1 172.28.80.1 192.168.99.39 Internet 192.168.98.11 192.168.100.4 192.168.100.3 192.168.100.1

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

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

  7. 8 16 24 32 Class A 0 Network ID Host ID Class B 10 Network ID Host ID Class C 110 Network ID Host ID Class D 1110 Multicast Address Class E 11110 Unused IP Address Class 32 bits address length, contain 2 parts • Network identifier • Host identifier

  8. IP Address Class A 0 7 24 0.0.0.0 -127.255.255.255 224 16,677,214 B 10 14 16 128.0.0.0 -191.255.255.255 216 65,534 C 110 21 8 192.0.0.0 -223.255.255.255 28 254 D 1110 28 - 224.0.0.0-239.255.255.255 E 11110 27 - 240.0.0.0-247.255.255.255 Initial bits Bit net range address spaces Class Bit host usable

  9. Special Address • Host ID “all 0s” is reserved to refer to network number • 192.168.100.0, 158.108.0.0, 18.0.0.0 • Host ID “all 1s” is reserved to broadcast to all hosts on a specific network • 192.168.100.255, 158.108.255.255, 18.255.255.255 • Address 0.0.0.0 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 255.255.255.255 is reserve to broadcast to every host on the local network (limited broadcast)

  10. Private Address Reserve for Intranet or private network • 10.0.0.0 – 10.255.255.255 (1 class A ) • 172.16.0.0 – 172.31.255.255 (16 class B) • 192.168.0.0 – 192.128.255.255 (256 class C)

  11. Class B Class A C D E 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

  12. 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 than32 subnets • organization more than 4096 hosts • class C: divided into allocated block to distributed reginal

  13. 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

  14. ... 150.0.255.254 150.0.0.1 150.0.0.2 Problem with Large Network • Class B “Flat Network” more than 60,000 hosts • How to manage? • Performance?

  15. 150.0.10.1 150.0.40.1 150.0.200.1 150.0.1.1 150.0.10.2 150.0.40.2 150.0.200.2 150.0.1.2 Router Problem with Large Network • Class B “subdivided network” to smaller group with router

  16. 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

  17. host ID Network ID Subnet address Host address Choose appropriate size How to assign subnet • Divide host ID into 2 pieces • Class B address such as 150.0 might use its third byte to identify subnet • subnet1 150.0.1.X X = host address range from 1-254 • subnet2 150.0.200.X

  18. 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 1111 1111 1111 1111 0000 0000 subnet mask = 255.255.255.0 * zero bit are used to mask out the host number resulting the network address

  19. Subnet Mask Subnet mask 255.255.255.0 for class B tells: • network has been partition to 254 subnets 150.10.1.X to 150.10.254.X • logic “and” between IP address with mask yields network address 150.10.1.55 150.10.240.243 and and 255.255.255.0 255.255.255.0 150.10.1.0 150.10.240.0

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

  21. Subnet Class B Example • 255.255.0.0 (0000 0000 0000 0000) 0 subnet with 65534 hosts (default subnet) • 255.255.192.0 (1100 0000 0000 0000) 2 subnets with 16382 hosts • 255.255.252.0 (1111 1100 0000 0000) 62 subnets with 1022 hosts • 255.255.255.0 (1111 1111 0000 0000) 254 subnets with 254 hosts • 255.255.255.252 (1111 1111 1111 11000) 16382 subnets with 2 hosts

  22. Subnet Class C Example • 255.255.255.0 ( 0000 0000) 0 subnets with 254 hosts (default subnet) • 255.255.255.192 (1100 0000) 2 subnets with 62 hosts • 255.255.255.224 (1110 0000) 6 subnets with 30 hosts • 255.255.255.240 (1111 0000) 14 subnets with 14 hosts

  23. Subnet Interpretation IP Address Subnet mask Interpretation 158.108.2.71 255.255.255.0 host 71 on subnet 158.108.2.0 150.10.25.3 255.255.255.192 host 3 on subnet 150.10.25.0 130.122.34.132 255.255255.192 host 4 on subnet 130.122.34.128 200.190.155.66 255.255.255.192 host 2 on subnet 200.190.155.64 18.20.15.2 255.255.0.0 host 15.2 on subnet 18.20.0.0

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

  25. 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}

  26. 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 255.255.255.0 wastes 250 IPs) • Variable Length Subnet : the subnets may use difference subnet masks • pros: utilize address space • cons: required well managment

  27. 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

  28. VLSM Sample Case Picture from Kasetsart university

  29. CIDRClassless Inter-Domain Routing

  30. 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

  31. 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

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

  33. Prefix Length Distribution 70000 60000 50000 40000 Number of Prefixes 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

  34. How to solve • Topological allocate IP address assignment • We divide the world into 8 regions (RFC 1466) Multi regional 192.0.0.0 - 193.255.255.255 Europe 194.0.0.0 - 195.255.255.255 Others 196.0.0.0 - 197.255.255.255 North America 198.0.0.0 - 199.255.255.255 Central/South America 200.0.0.0 - 201.255.255.255 Pacific Rim 202.0.0.0 - 203.255.255.255 Others 204.0.0.0 - 205.255.255.255 Others 206.0.0.0 - 207.255.255.255 IANA Reserved 208.0.0.0 - 223.255.255.255

  35. Classless Interdomain Routing • Class C address’s concept becomes meaningless on these route between domain, the technique is callClassless 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 BGP4 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)

  36. Supernetting • An organization has been allocate a block of class C address in 2n 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 to network outside as a single network 11111111 11111111 11111100 00000000 255.255.252.0

  37. Supernetting Sample • An organization with 4 class C 193.0.32.0 , 193.0.33.0 , 193.0.34.0 , 193.0.35.0 11111111 11111111 11111100 00000000 mask 255.255.252.0 11000001 00000000 00100000 00000000 net 193.0.32.0 11000001 00000000 00100001 00000000 net 193.0.33.0 11000001 00000000 00100010 00000000 net 193.0.34.0 11000001 00000000 00100011 00000000 net 193.0.35.0 Bit wise AND results 193.0.32.0: 11000001 00000000 00100000 00000000 • This organization’s network has changed from 4 net to a single net with 1,022 hosts

  38. The longest Match Supernetting • Europe has 194.0.0.0 - 195.255.255.255 with mask 254.0.0.0 • A case of one organization (195.0.16.0 - 195.0.36.0 mask 255.255.254.0) 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 (255.255.254.0 is longer than 254.0.0.0), then route to the organization

  39. 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 130K entries in core routers) • Short term solution to solve routing problem • limitation: not all host/router software allows supernet mask

  40. IPv6

  41. IPv4’s Limitations • Two driving factors : addressing and routing • Addressing : address depletion concerns • Internet exhaust the IPv4 address space between 2005 and 2011 [RFC1752]. • Routing : routing table explosion • Currently ~120K entries in core router • More factors... • Opportunity to optimized on many years of deployment experience • New features needed : multimedia, security, mobile, etc..

  42. Key Issues The new protocol MUST • Support large global internetworks • A clear way to transition IPv4 based networks

  43. What is IPv6? • IPv6 is short for "Internet Protocol Version 6". • IPv6 is the "next generation" protocol designed by the IETF to replace the current version Internet Protocol, IP Version 4

  44. IPV6 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 • IPv4 compatibility

  45. IPV6 Address Representation • Hexadecimal values of the eight 16-bit pieces x:x:x:x:x:x:x:x • Example FEDC:BA98:7654:3210:FEDC:BA98:7654:3210 1080:0:0:0:8:800:200C:417A • Compressed form: "::" indicates multiple groups of 16-bits of zeros. 1080:0:0:0:8:800:200C:417A 1080::8:800:200C:417A FF01:0:0:0:0:0:0:101 FF01::101 0:0:0:0:0:0:0:1 ::1 0:0:0:0:0:0:0:0 ::

  46. IPV6 Address Representation(cont) • Mixed environment of IPv4 and IPv6 address IPv4-compatible IPv6 address technique for hosts and routers to dynamically tunnel IPv6 packets over IPv4 routing infrastructure 0:0:0:0:0:0:13.1.68.3 => :: 13.1.68.3 IPv4-mapped IPv6 address represent the addresses of IPv4-only nodes (those that do not support IPv6) as IPv6 addresses IPv4-only IPv6-compatible addresses are sometimes used/shown for sockets created by an IPv6-enabled daemon, but only binding to an IPv4 address. These addresses are defined with a special prefix of length 96 (a.b.c.d is the IPv4 address): 0:0:0:0:0:FFFF:129.144.52.38/96 => :: FFFF:129.144.52.38/96 http://www.tldp.org/HOWTO/Linux+IPv6-HOWTO/x324.html

  47. Format Prefix • Format Prefix : • Leading bits indicate specific type of an IPv6 address • The variable-length field • Represented by the notation: IPv6-address/prefix-length Example : the 60-bit prefix 12AB00000000CD3 12AB:0000:0000:CD30:0000:0000:0000:0000/60 12AB::CD30:0:0:0:0/60 12AB:0:0:CD30::/60

  48. 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

  49. Address Types • Unspecified address, 0:0:0:0:0:0:0:0 or :: • Loopback address, 0:0:0:0:0:0:0:1 of ::1 • Global address, 2000::/3 and E000::/3 currently only 2000::/3 is being assigned • Link local address, FE80::/64 • Site local address, FEC0::/10

  50. IPV6 Address Allocation