IP Address

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 assi gned to network interface card, refer to

MAC address or Ethernet Address 48(bi t s)–00503004

3

Converting Host Name to MAC Addresscs05.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)

4

IP Address with RouterIP 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

172.28.80.15172.28.80.16172.28.85.116172.28.85.120

172.28.85.1172.28.80.1

192.168.100.3192.168.100.4192.168.100.1

192.168.99.39

192.168.98.11Internet

5

Addressing Concept• Partitions address into 2 fields

* network address* node address

6

IP Address

Network Host

32 bits8,16,24 bits

8 bits 8 bits 8 bits 8 bits32 bits

172 28 80 96. . .10101100000111000101000001100000

7

IP Address Class32 bits address length, contain 2

parts• Network identifier• Host identifier

Class A8 16 24 32

Host IDNetwork ID0

Multicast Address1110Unused11110

Host IDNetwork ID110Host IDNetwork ID10Class B

Class CClass DClass E

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 - 224.0.0.0-239.255.255.255E 11110 27 - 240.0.0.0-247.255.255.255

ClassInitial bits

Bit netBithost range address spacesusable

9

Special Address• Host ID 0“all s” is reserved to refer to network n

umber– 1921681000 15810800 1. . . , . . . ,8000. . .

• Host ID “ 1 ”all s is reserved to broadcast to all h osts on a specific network

– 192168100255 15810825. . . , . . 5255 18255255255. , . . .

• Address 0 .0 .0 .0 means “ ”• m mmmm 1 27000 “this node” (loc

al loopback). Message sent to this address will nev er leave the local host

• 255255255255Address . . . is reserve to broadcast to every host on the local network (limited b

roadcast)

10

Private AddressReserve 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

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 AClass B

CD

E

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 network2. Requires fewer than 512 addresses : 2 contiguous class C networks3. Requires fewer than 1024 addresses : 4 contiguous class C networks4. Requires fewer than 2048 addresses : 8 contiguous class C networks5. Requires fewer than 4096 addresses : 16 contiguous class C networks6. Requires fewer than 8192 addresses : 32 contiguous class C networks7. Requires fewer than 16384 addresses : 64 contiguous class C networks

14

Problem with Large Network•Class B “Flat Network” more

than 60,000 hosts–How to manage?–Performance?...150.0.0.1150.0.0.2 150.0.255.254

15

Problem with Large Network•Class B “subdivided

network” to smaller group with router

150.0.10.1150.0.10.2

150.0.40.1150.0.40.2

150.0.200.1150.0.200.2

150.0.1.1150.0.1.2

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

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

Network IDSubnet addressHost addresshost ID

Chooseappropriate size

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 2552552550Subnet mask . . . for cl

m mmmmmm:• 254network has been partition to subnets

150101 15010254. . .X to . . .X• mmmm mmm mm mmmmmmm m mmm m mmm mmmmmm m“ ”

mmmmmm mmmmmmm15010155. . .15010240243 mmm mmm2552552550. . .2552552550. . .15010. .1015010. .2400

20

Subnet Mask BitsUse 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)



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 Interpretation158.108.2.71 255.255.255.0 host 71 on subnet

158.108.2.0150.10.25.3 255.255.255.192 host 3 on subnet

150.10.25.0130.122.34.132 255.255255.192 host 4 on subnet

130.122.34.128200.190.155.66 255.255.255.192 host 2 on subnet

200.190.155.6418.20.15.2 255.255.0.0 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” res

ults

if dest IP addr & subnet mask = = my IP addr & subnet mask

send packet on local network { dest IP addr is on the samesubnet}

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 host s needs a subnet mask that accom

modate only few hosts– A subnet with many hosts need a s

ubnet 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

0

20000

40000

60000

80000

100000

120000

140000

Aug-87 May-90 J an-93 Oct-95 J ul-98 Apr-01 J an-04

Num

ber

of p

refix

es

33

Prefix Length Distribution

0

10000

20000

30000

40000

50000

60000

70000

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

Num

ber

of

Pref

ixes

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 - 193.255.255.255Europe 194.0.0.0 - 195.255.255.255Others 196.0.0.0 - 197.255.255.255North America 198.0.0.0 - 199.255.255.255Central/South America200.0.0.0 - 201.255.255.255Pacific Rim 202.0.0.0 - 203.255.255.255Others 204.0.0.0 - 205.255.255.255Others 206.0.0.0 - 207.255.255.255IANA Reserved 208.0.0.0 - 223.255.255.255

35

Classless Interdomain Routing• Class C address’s concept becomes mea

ningless on these route between domain , the technique is call Classless Interdo

main Routing or CIDR or Supernet• Kay concepts is to allocate multiple IP ad

dress in the way that allow summarizatio n into a smaller number of routing table (

route aggregate)• CIDR is supported by BGP4 and based o

n r out e aggr egat i on– 16 class C addresses can be summarized

m mmmmmm mmmmmmm mmmmm mmmmmmm mmm mmmm m ( singler out e ent r y f or a mai n t r unks bet ween t h esear eas)

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 011111111 11111111 11111100 00000000

255.255.252.0

(Super) netmask4 class C networks appearto network outside as a single network

37

Supernetting Sample• An organization with 4 class C

193.0.32.0 , 193.0.33.0 , 193.0.34.0 , 193.0.35.011111111 11111111 11111100 00000000 mask 255.255.252.011000001 00000000 00100000 00000000 net 193.0.32.011000001 00000000 00100001 00000000 net 193.0.33.011000001 00000000 00100010 00000000 net 193.0.34.0 11000001 00000000 00100011 00000000 net 193.0.35.0Bit 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• - 194000 1952Europe has . . . .

55255255 254. . with mask . 000. .

• - mmmmm (195.0.16.0 195.0.36.0 255.255.254.0)mmmmmmmmm mmmmmmm mmmmm

• m mmmmmm m1 950201 othEurope’sandt hi s or gani zat i on. Howt o do?

• mmmm mmmmm mm (255.255.254.0 254.0.0.0), t he or gani zat i on

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 piecesx:x:x:x:x:x:x:x

ExampleFEDC:BA98:7654:3210:FEDC:BA98:7654:32101080:0:0:0:8:800:200C: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

addressIPv4-compatible IPv6 addresstechnique for hosts and routers to dynamically tunnel IPv6packets over IPv4 routing infrastructure

0:0:0:0:0:0:13.1.68.3 => :: 13.1.68.3

http://www.tldp.org/HOWTO/Linux+IPv6-HOWTO/x324.html

represent the addresses of IPv4-only nodes (those that do not support IPv6) as IPv6 addressesIPv4-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):

IPv4-mapped IPv6 address

0:0:0:0:0:FFFF:129.144.52.38/96 => :: FFFF:129.144.52.38/96

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

12AB:0000:0000:CD30:0000:0000:0000:0000/6012AB::CD30:0:0:0:0/6012AB:0:0:CD30::/60

Example : the 60-bit prefix 12AB00000000CD3

48

Type of AddressesThree type of addresses• UNICAST : defines a single interfaceA packet sent to a unicast address is delivered to

the interface identified by that address.• ANYCAST : defines a set of interfacesA packet sent to an anycast address is delivered to one of the interfaces• MULTICAST : defines a set of interfacesA 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 AllocationAllocation Prefix bit Prefix

formatfraction ofaddressapace

Reserved 0000 0000 0::/8 1/256Unassigned 0000 0001 100::/8 1/256

Reserved for NSAP Allocation 0000 001 200::/7 1/128Reserved for IPX Allocation 0000 010 400::/7 1/128Unassigned 0000 011 600::/7 1/128Unassigned 0000 1 800::/5 1/32Unassigned 0001 1000::4 1/16

Aggregatable Global Unicast Addresses 001 2000::/3 1/8Unassigned 010 4000::/3 1/8Unassigned 011 6000::/3 1/8Unassigned 100 8000::/3 1/8Unassigned 101 A000::/3 1/8Unassigned 110 C000::/3 1/8Unassigned 1110 E000::/4 1/16Unassigned 1111 0 F000::/5 1/32Unassigned 1111 10 F800::/6 1/64Unassigned 1111 110 FC00::/7 1/128Unassigned 1111 1110 0 FE00::/9 1/512

Link-Local Unicast Addresses 1111 1110 10 FE80::/10 1/1024Site-Local Unicast Addresses 1111 1110 11 FEC0::/10 1/1024Multicast Addresses 1111 1111 FF00::/8 1/256

51

Address RegistriesAddress registries for IPv6 are the same

one as for IPv4, 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

52

Aggregatable Unicast AddressThree level hierarchy:• Public Topology : providers

and exchanges who provide public Internet transit services

(P1, P2, P3, P4, X1, X2, P5 and P6)

• Site Topology : does not

provide public transit service to nodes outside of the site

(S1, S2, S3, S4, S5 and S6) • Interface Identifier: interfaces

on links

X1

P1

P2

P3

P4

x2

P5 P6S1 S2 S3

S4 S5 S6

53

Aggregatable Unicast Address

FP TLA ID RES NLA ID SLA ID Interface ID 3 13 8 24 16 64 bits

Public Topology SiteTopology Interface

IdentifierTLA= Top Level AggregationRES= ReservedNLA=Next-Level AggregationSLA=Site-Level Aggregation

FP=Format Prefix= 001

54

Header Comparison• Removed (6)

– ID, Flags, frag offset– TOS, hlen– header checksum

• Changed: (3)– total length=> payload– protocol => next header– TTL=> hop limit

• Added: (2)– Traffic class– flow label

• Expanded– address 32 bits to 128 bits

vers hlen TOS total length identification flags frag offset TTL protocol header checksum

source addressdestination addressoptions and padding

0 15 16 31

20bytes

vers traffic class flow label pay load length next header hop limit

source address

destination address

40bytes

IPv4

IPv6

55

IPv6 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 4th octets

EUI-48 EUI-64

00:06:5B:DA:45:AD = 00:06:5B:FF:FE:DA:45:AD

56

Auto configuration“Plug and play” feature• Stateless mode :via ICMP (no server required)

• Stateful server mode : via DHCP

Prefix4c00::/80

Link Address00:A0:C9:1E:A5:B6

IPv6 Address4c00::A0:C9FF:EF1E:A5B6

Router adv.

DHCP request

DHCP response

00:A0:C9:1E:A5:B6

4c00::A0:C9FF:FE1E:A5B6

DHCPserver

57

Security

• Authentication/Confidential• Authentication:

– MD5 based• Confidential :

– payload encryption– Cipher Block Chaining mode of the

Data Encryption Standard (DES-CBC)

58

Support Protocols• ICMPv6 [RFC1885]• DHCPv6• DNS extensions to support IPv6

[RFC1886]• Routing Protocols

– RIPv6 [RFC2080]– OSPFv6– IDRP – IS-IS– Cisco EIGRP

59

Dual Stack• Dual stack hosts support both IPv4 and

IPv6• Determine stack via DNS

IPV6 IPv4Dual stack host

ApplicationTCP

IPv6 IPv4Ethernet

60

Tunneling: automatic tunneling• Encapsulate IPv6 packet in IPv4• Rely on IPv4-compatible IPv6 address

IPv6 host IPv4/6 hostIPv4 Network::1.2.3.4 2.3.4.5

6 traffic flow label

payload len next hops src = ::1.2.3.4 (IPv4-compatible IPv6 adr)

dst = ::2.3.4.5 (IPv4-compatible IPv6 adr)

payload

4 hl TOS len frag id frag ofsTTL prot checksum src: 1.2.3.4 dst: 2.3.4.56 traffic flow label


dst = ::2.3.4.5 (IPv4-compatible IPv6 adr)

payload

4 hl TOS len frag id frag ofsTTL prot checksum src: 1.2.3.4 dst: 2.3.4.56 traffic flow label


dest = ::2.3.4.5 (IPv4-compatible IPv6 adr)

payload

::2.3.4.5 2.3.4.5 2.3.4.5

R1 R2

61

Tunneling : configured tunneling• Encapsulate IPv6 packet in IPv4• Rely on IPv6-only address

IPv6 host IPv6 hostIPv4 Network::1:2:3:4 :: 2:3:4:5


payload len next hops src = ::1:2:3:4 (IPv6 adr)

dst = ::2:3:4:5 (IPv6 adr)

payload

4 hl TOS len frag id frag ofsTTL prot checksum src = R1 dst =R26 traffic flow label

payload len next hops src =::1:2:3:4 (IPv6 adr)

dst = ::2:3:4:5 (IPv6 adr)

payload

::2:3:4:5 R2 ::2:3:4:5

R1 R2



dst = ::2:3:4:5 (IPv6 adr)

payload

IPv6 address(IPv4-compatible address are unavailable)

62

Header Translation Full IPv6 system need to support few IPv4-only systems rely on

IPv4-mapped IPv6 address

IPv6 host IPv4 hostIPv6 Network::1:2:3:4 2.3.4.5



dst = ::2.3.4.5 (IPv6 adr)

payload

4 hl TOS len frag id frag ofsTTL prot checksum src = R1 dst =R2 payload

::2:3:4:5 ::2.3.4.5 2.3.4.5

R1 R2



dst = ::2.3.4.5 (IPv6 adr)

payload

63

Migration Steps

1. Upgrade DNS servers to handle IPv6 Address

2. Introduce dual stack systems that support IPv4 and IPv6

3. Rely on tunnels to connect IPv6 networks separated by IPv4 networks

4. Remove support for IPv45. Rely on header translation for IPv4-

only systems

64

Conclusion• IPv6 will provide for future Internet

growth and enhancement• IPv6 :

–solve the Internet scaling problem–support large hierarchical address–provide a flexible transition mechanism–interoperate with IPv4–provide a platform for new Internet functionality

IP Address

Documents

Transcript of IP Address