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 assigned to
  network interface card, refer to MAC address or
  Ethernet Address (48 bits)
• 005cf03b004a

3
Converting Host Name to MAC Address

• cs05.cs.psu.ac.th
• 172.28.80.96
• 0050ba499db9

• Resolve IP address by Domain Name System(DNS)
• Resolve MAC address by Address Resolution
  Protocol(ARP)

4
IP Address with Router

• 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

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
192.168.100.3
192.168.100.4
192.168.100.1
5
Addressing Concept

• Partitions address into 2 fields
• network address
• node address

6
IP Address
7
IP Address Class

• 32 bits address length, contain 2 parts
• Network identifier
• Host identifier

8
IP Address Class
Initial bits
Bit net
range
address spaces
Class
Bit host
usable

• 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 - 224.0.0.0-239.255.25
  5.255
• E 11110 27 - 240.0.0.0-247.255.255.
  255

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
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
Problem with Large Network

• Class B Flat Network more than 60,000 hosts
• How to manage?
• Performance?

15
Problem with Large Network

• Class B subdivided network to smaller group
  with router

16
Subnetwork Benefits

• Increase the network managers 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

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 Managers 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 addresss 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 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 organizations 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 Europes 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
IPv4s 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
• xxxxxxxx
• Example
• FEDCBA9876543210FEDCBA9876543210
• 10800008800200C417A
• Compressed form "" indicates multiple groups
  of 16-bits of zeros.
• 10800008800200C417A
  10808800200C417A
• FF01000000101 FF01101
  
• 00000001 1
• 00000000

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
00000013.1.68.3 gt 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)
00000FFFF129.144.52.38/96 gt
FFFF129.144.52.38/96
http//www.tldp.org/HOWTO/LinuxIPv6-HOWTO/x324.ht
ml
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
12AB00000000CD300000000000000000/60 12ABC
D300000/60 12AB00CD30/60
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, 00000000 or
• Loopback address, 00000001 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
51
Address Registries

• Address 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 Address

• Three 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

53
Aggregatable Unicast Address
3 13 8
24
16
64 bits
FP TLA ID RES NLA ID SLA
ID Interface ID
Public Topology
Site Topology
Interface Identifier
FPFormat Prefix 001
TLA Top Level Aggregation RES
Reserved NLANext-Level Aggregation SLASite-Level
Aggregation
54
Header Comparison

• Removed (6)
• ID, Flags, frag offset
• TOS, hlen
• header checksum
• Changed (3)
• total lengthgt payload
• protocol gt next header
• TTLgt hop limit
• Added (2)
• Traffic class
• flow label
• Expanded
• address 32 bits to 128 bits

0 15 16
31
vers hlen TOS total
length identification flags
frag offset TTL protocol
header checksum source address destination
address options and padding
20 bytes
IPv4
vers traffic class
flow label pay load length next header
hop limit source address destination
address
40 bytes
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
• 00065BDA45AD 00065BFFFEDA45AD

56
Auto configuration

• Plug and play feature
• Stateless mode via ICMP (no server required)
• Stateful server mode via DHCP

Prefix 4c00/80
IPv6 Address 4c00A0C9FFEF1EA5B6
Link Address 00A0C91EA5B6
00A0C91EA5B6
DHCP request
DHCP server
DHCP response
4c00A0C9FFFE1EA5B6
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

Application TCP IPv6 IPv4 Ethernet
IPV6
IPv4
Dual stack host
60
Tunneling automatic tunneling

• Encapsulate IPv6 packet in IPv4
• Rely on IPv4-compatible IPv6 address

IPv4/6 host
IPv6 host
IPv4 Network
2.3.4.5
1.2.3.4
R1
R2
2.3.4.5
2.3.4.5
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 ofs TTL prot checksum
src 1.2.3.4 dst
2.3.4.5 6 traffic flow label
payload len next hops
src 1.2.3.4 (IPv4-compatible IPv6 adr)
dest 2.3.4.5 (IPv4-compatible IPv6
adr) payload
4 hl TOS len frag id
frag ofs TTL prot checksum
src 1.2.3.4 dst
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
61
Tunneling configured tunneling

• Encapsulate IPv6 packet in IPv4
• Rely on IPv6-only address

IPv6 host
IPv4 Network
IPv6 host
2345
1234
IPv6 address (IPv4-compatible address are
unavailable)
R1
R2
2345
R2
2345
6 traffic flow label payload
len next hops src
1234 (IPv6 adr)
dst 2345 (IPv6 adr)
payload
4 hl TOS len frag id
frag ofs TTL prot checksum
src R1 dst R2 6
traffic flow label payload len
next hops src 1234
(IPv6 adr) dst
2345 (IPv6 adr)
payload
6 traffic flow label payload
len next hops src
1234 (IPv6 adr)
dst 2345 (IPv6 adr)
payload
62
Header Translation

• Full IPv6 system
• need to support few IPv4-only systems
• rely on IPv4-mapped IPv6 address

IPv4 host
IPv6 Network
IPv6 host
2.3.4.5
1234
R1
R2
2.3.4.5
2.3.4.5
2345
6 traffic flow label payload
len next hops src
1234 (IPv6 adr)
dst 2.3.4.5 (IPv6 adr)
payload
6 traffic flow label payload
len next hops src
1234 (IPv6 adr)
dst 2.3.4.5 (IPv6 adr)
payload
4 hl TOS len frag id
frag ofs TTL prot checksum
src R1 dst R2
payload
63
Migration Steps

• Upgrade DNS servers to handle IPv6 Address
• Introduce dual stack systems that support IPv4
  and IPv6
• Rely on tunnels to connect IPv6 networks
  separated by IPv4 networks
• Remove support for IPv4
• 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