Efficient ip addressing
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Efficient IP Addressing. Subnetting. forwarding table. Review: IP Addressing. Suppose hosts had arbitrary addresses Then every router would need a lot of information …to know how to direct packets toward the host. 1.2.3.4. 5.6.7.8. 2.4.6.8. 1.2.3.5. 5.6.7.9. 2.4.6.9. host. host.

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Efficient IP Addressing

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Efficient ip addressing

Efficient IP Addressing

Subnetting


Review ip addressing

forwarding table

Review: IP Addressing

  • Suppose hosts had arbitrary addresses

    • Then every router would need a lot of information

    • …to know how to direct packets toward the host

1.2.3.4

5.6.7.8

2.4.6.8

1.2.3.5

5.6.7.9

2.4.6.9

...

...

host

host

host

host

host

host

LAN 2

LAN 1

router

router

router

WAN

WAN

1.2.3.4

1.2.3.5


Review ip addressing scalability

Review: IP Addressing scalability

  • Number related hosts from a common subnet

    • 1.2.3.0/24 on the left LAN

    • 5.6.7.0/24 on the right LAN

1.2.3.4

1.2.3.7

1.2.3.156

5.6.7.8

5.6.7.9

5.6.7.212

...

...

host

host

host

host

host

host

LAN 2

LAN 1

router

router

router

WAN

WAN

1.2.3.0/24

5.6.7.0/24

forwarding table


Review scalability adding new hosts

Review: Scalability- Adding new hosts

  • No need to update the routers

    • E.g., adding a new host 5.6.7.213 on the right

    • Doesn’t require adding a new forwarding entry

1.2.3.4

1.2.3.7

1.2.3.156

5.6.7.8

5.6.7.9

5.6.7.212

...

...

host

host

host

host

host

host

LAN 2

LAN 1

router

router

router

host

WAN

WAN

5.6.7.213

1.2.3.0/24

5.6.7.0/24

forwarding table


Some questions ip addressing

Some Questions: IP Addressing

  • How are IP addresses managed

    • Given out

      • Single point

        • Hierarchical

    • Documentation

      • Record of what is given out and to whom

    • Accounting

      • What remains?


Giving out obtaining a block of addresses

Giving out: Obtaining a Block of Addresses

  • The Internet Assigned Numbers Authority (IANA) is responsible for the global coordination of IP addressing, and other Internet protocol resources

    • Internet Corporation for Assigned Names and Numbers (ICANN)

      • Allocates large address blocks to Regional Internet Registries

    • Regional Internet Registries (RIRs)

      • Allocates address blocks within their regions

      • Allocated to Internet Service Providers and large institutions

    • Internet Service Providers (ISPs)

      • Allocate address blocks to their customers

      • Who may, in turn, allocate to their customers…

      • Prefix: assigned to an institution

        • Addresses: assigned by the institution to their nodes


Regional internet registries

Regional Internet Registries

  • Five RIRs to cater to five large global regions

  • African Network Information Centre (AfriNIC)for Africa

  • American Registry for Internet Numbers (ARIN)for the United States, Canada, and several parts of the Caribbean region.

  • Asia-Pacific Network Information Centre(APNIC)for Asia, Australia, and neighboring countries

  • Latin America and Caribbean Network Information Centre(LACNIC)for Latin America and parts of the Caribbean region

  • RIPE NCC (RIPE NCC) for Europe, the Middle East, and Central Asia


Record figuring out who owns an address

Record: Figuring Out Who Owns an Address

  • Address registries

    • Public record of address allocations

    • Internet Service Providers (ISPs) should update when giving addresses to customers

    • However, records are notoriously out-of-date

  • Ways to query

    • http://www.db.ripe.net/whois to find RIPE NCC database for IP addresses

    • http://www.geektools.com/whois.php


Are 32 bit addresses enough

Are 32-bit Addresses Enough?

  • Not all that many unique addresses

    • 232 = 4,294,967,296 (just over four billion)

    • Plus, some are reserved for special purposes

    • And, addresses are allocated in larger blocks

  • And, many devices need IP addresses

    • Computers, PDAs, routers, tanks, toasters, …

  • Long-term solution: a larger address space

    • IPv6 has 128-bit addresses (2128 = 3.403 × 1038)

  • Short-term solutions: limping along with IPv4

    • Private addresses

    • Network address translation (NAT)

    • Dynamically-assigned addresses (DHCP)


Hard policy questions

Hard Policy Questions

  • How much address space per geographic region?

    • Equal amount per country?

    • Proportional to the population?

    • What about addresses already allocated?

  • Address space portability?

    • Keep your address block when you change providers?

  • Keeping the address registries up to date?

    • What about mergers and acquisitions?

    • Delegation of address blocks to customers?

      • As a result, the registries are horribly out of date


What the ip address meltdown means for you

What the IP Address Meltdown Means For You

Article in PC world: posted on Dec 1, 2010 5:39 pm: Brief synopsis

  • The world is running out of IPv4 Internet addresses, without which the Internet can't function in its existing form.

  • This has been known for some time, of course, but the situation has become a little more urgent with the news that in October and November, nearly all of the remaining blocks of addresses were assigned to various Regional Internet Registries (RIR) around the world…….

  • Remaining five blocks of IP addresses given out by beginning of 2011 to the five RIRs…..


Objectives

Objectives

  • Economising IP address use:

  • To subnet an IP Address from given network requirements

    • Why subnet

    • Hierarchy in subnetted addresses

    • How to subnet

      • Identify network class

      • Identify network requirements

      • Calculate sub-network addresses

      • Calculate available host addresses

      • Calculate new subnet mask

      • Assign new addresses


Advantages of subnetting

Advantages of Subnetting

  • With subnetting, IP addresses use a 3-layer hierarchy:

    • Network

    • Subnet

    • Host

  • Improves efficiency of IP addresses by not consuming an entire address space for each physical network.

  • Reduces router complexity. Since external routers do not know about subnetting, the complexity of routing tables at external routers is reduced.

  • Note: Length of the subnet mask need not be identical at all subnetworks.


  • Subnetting

    Subnetting

    Subnetting

    University Network

    • Problem: Organizations have multiple networks which are independently managed

      • Solution 1: Allocate one or more addresses for each network

        • Difficult to manage

        • From the outside of the organization, each network must be addressable.

      • Solution 2: Add another level of hierarchy to the IP addressing structure

    Engineering

    School

    Medical

    School

    Library


    Two level hierarchy

    Two-level hierarchy

    • The network prefix identifies a network and the host number identifies a specific host (actually, interface on the network).

    • How do we know how long the network prefix is?

      • The network prefix is implicitly defined using class-based addressing

      • The network prefix is indicated by a subnet mask or netmask

    network prefix

    host number


    Subnetting three level hierarchy

    Subnetting- Three level Hierarchy

    • Split the host number portion of an IP address into a subnet number and a (smaller) host number.

    • Result is a 3-layer hierarchy

    • Then:

      • Subnets can be freely assigned within the organization

      • Internally, subnets are treated as separate networks

      • Subnet structure is not visible outside the organization

    network prefix

    host number

    network prefix

    subnet number

    host number

    extended network prefix


    Typical addressing plan for an organization that uses subnetting

    Typical Addressing Plan for an Organization that uses subnetting

    • Each layer-2 network (Ethernet segment, FDDI segment) is allocated a subnet address.

    128.143.0.0/16


    Advantages of subnetting1

    Advantages of Subnetting

    • With subnetting, IP addresses use a 3-layer hierarchy:

      • Network

      • Subnet

      • Host

  • Improves efficiency of IP addresses by not consuming an entire address space for each physical network.

  • Note: Length of the subnet mask need not be identical at all subnetworks.


  • Task create subnetwork addresses

    Task: Create subnetwork addresses

    Create subnetwork addresses for 20 different network addresses, using IP address 201.222.5.0

    sales

    Admin


    Convert the decimal dotted notation address 201 222 5 0 to binary

    Convert the decimal dotted notation address 201.222.5.0 to binary:

    STEP 1: Convert the decimal dotted notation

    11001001.11011110.00000101.00000000


    Determine the class of the ip address 201 222 5 0

    Determine the Class of the IP Address 201.222.5.0:

    Step 2: Class of the IP Address

    CLASS C


    Efficient ip addressing

    Based on the Class, determine what part of the IP address is the network portion and what part of the address is the host portion:201.222.5.0

    Step 3. Find Network portion and Host portion

    11001001.11011110.00000101.00000000

    Network .Network .Network .Host

    201. 222. 5. 0


    Efficient ip addressing

    Determine how many bits you need to borrow from the last octet (host portion) of the IP Address to give you the needed 20 subnets:

    Step 4: How many bits to borrow

    2 to the power of 2 = 4 subnets (less 2)

    2 to the power of 3 = 8 subnets (less 2)

    2 to the power of 4 = 16 subnets (less 2)

    2 to the power of 5 = 32 subnets (less 2)

    2 to the power of 6 - 64 subnets (less 2)


    Efficient ip addressing

    Since you borrowed five bits from the host for subnets, determine how many hosts can you have on each of those subnets?

    Step 5: Determine how many hosts can you have on each of those subnets

    2 to the power of 3 = 8 hosts (less 2) giving you 6 hosts per subnet.

    11001001.11011110.00000101.00000000

    Remaining bits = Number of hosts


    Determine the subnetworks numbers from the borrowed 5 bits 32 possible combinations

    Determine the Subnetworks’ Numbers from the borrowed 5 bits: 32 possible combinations

    Step 6: Determine the Binary Subnetworks Field Numbers

    Subnet #Binary Subnetwork

    100000

    200001

    300010

    400011

    500100

    600101

    700110

    800111

    901000

    1001001

    1101010

    1201011

    1301100

    ..……..

    3211111


    Efficient ip addressing

    Step 7: Determine the Range of Binary Host Field Numbers for Each Subnetwork:

    Determine the Range of Binary Host Field Numbers for Each Subnetwork: 3 bits: 8 possible hosts on each subnet

    Subnet #Binary SubnetworkRange of Host #’s

    100000

    200001000 - 111

    300010000 - 111

    400011000 - 111

    500100000 - 111

    600101000 - 111

    700110000 - 111

    800111000 - 111

    901000000 - 111

    1201100000 - 111

    ..……..-----------

    3211111


    Efficient ip addressing

    Step 8: Determine Decimal Host Numbers for Each Subnetwork

    Subnet #Binary SubnetworkRange of Host #’sDecimal Host Numbers

    100000

    200001000 - 111 .8 - .15

    300010000 - 111.16 - .23

    400011000 - 111.24 - .31

    500100000 - 111 .32 - .39

    600101000 - 111.40 - .47

    700110000 - 111.48 - .55

    800111000 - 111.56 - .63

    901000000 - 111.64 - .71

    1001001000 - 111.72 - .79

    1101010000 - 111.80 - .87

    1201011000 - 111.88 - .95

    1301100000 - 111.96 - 103

    ..……..---------------------

    3211111


    Step 9 determine our subnet addresses

    Step 9. Determine Our Subnet Addresses:

    #Binary SubnetworkRange of Host #’sSubnet Address

    10000 0000

    20000 1000201.222.5.8

    3000 1 0 000201.222.5.16

    40001 1000201.222.5.24

    50010 0000201.222.5.32

    60010 1000201.222.5.40

    70011 0000201.222.5.48

    80011 1000 201.222.5.56

    90100 0000201.222.5.64

    100100 1000201.222.5.72

    110101 0000201.222.5.80

    120101 1000201.222.5.88

    130110 0000201.222.5.96

    ...…….------------------------------------

    321111 1000


    Step 10 determine host addresses of the six nodes of each subnet

    Step 10. Determine Host Addresses of the Six Nodes of Each Subnet:

    #SubnetworkRange of Host #’sDecimal Host #’sSubnet AddressHost Address Range

    100000

    200001 000 - 111 .8 - .15 201.222.5.8 201.222.5.9 thru 201.222.5.14

    300010 000 - 111 .16 - .23201.222.5.16 201.222.5.17 thru 201.222.5.22

    400011 000 - 111 .24 - .31201.222.5.24 201.222.5.25 thru 201.222.5.30

    500100 000 - 111 .32 - .39201.222.5.32 201.222.5.33 thru 201.222.5.38

    600101 000 - 111 .40 - .47201.222.5.40 201.222.5.41 thru 201.222.5.46

    700110 000 - 111 .48 - .55201.222.5.48 201.222.5.49 thru 201.222.5.54

    800111 000 - 111 .56 - .63201.222.5.56 201.222.5.57 thru 201.222.5.62

    901000 000 - 111 .64 - .71201.222.5.64 201.222.5.65 thru 201.222.5.70

    1001001 000 - 111 .72 - .79201.222.5.72 201.222.5.73 thru 201.222.5.78

    1101010 000 - 111 .80 - .87201.222.5.80 201.222.5.81 thru 201.222.5.86

    1201011 000 - 111 .88 - .95201.222.5.88 201.222.5.89 thru 201.222.5.94

    1301100 000 - 111 .96 - 103201.222.5.96 201.222.5.97 thru 201.222.5.--

    ...……. ----------- ------------------------- -------------------------------------

    3211111


    Efficient ip addressing

    Based on the Class, determine the subnet mask for network 201.222.5.0 (remember that 5 bits were borrowed):

    Step 12: Find New Subnet mask

    11111111.11111111.11111111.11111 000

    Network NetworkNetwork Subnet Host

    255. 255. 255. 248


    You did it

    YOU DID IT!


    Efficient ip addressing

    • African Network Information Centre (AfriNIC)[1] for Africa

    • American Registry for Internet Numbers (ARIN)[2] for the United States, Canada, and several parts of the Caribbean region.

    • Asia-Pacific Network Information Centre (APNIC)[3] for Asia, Australia, and neighboring countries

    • Latin America and Caribbean Network Information Centre (LACNIC)[4] for Latin America and parts of the Caribbean region

    • RIPE NCC[5] for Europe, the Middle East, and Central Asia


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