Efficient ip addressing
Sponsored Links
This presentation is the property of its rightful owner.
1 / 32

Efficient IP Addressing PowerPoint PPT Presentation


  • 74 Views
  • Uploaded on
  • Presentation posted in: General

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.

Download Presentation

Efficient IP Addressing

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


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

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

  • 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

  • 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

  • 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

  • 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

  • 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

  • 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?

  • 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

  • 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

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

  • 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

  • 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

    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

    • 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

    • 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

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

    128.143.0.0/16


    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

    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:

    STEP 1: Convert the decimal dotted notation

    11001001.11011110.00000101.00000000


    Determine the Class of the IP Address 201.222.5.0:

    Step 2: Class of the IP Address

    CLASS C


    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


    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)


    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

    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


    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


    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:

    #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:

    #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


    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!


    • 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


  • Login