IPv4 Addresses
This presentation is the property of its rightful owner.
Sponsored Links
1 / 30

IPv4 Addresses PowerPoint PPT Presentation


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

IPv4 Addresses. Internet Protocol: Which version?. There are currently two versions of the Internet Protocol in use for the Internet IPv4 (IP Version 4) Specified in 1980/81 (RFC 760, 791) Four byte addresses Universally deployed Problem : Address space almost exhausted

Download Presentation

IPv4 Addresses

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


Ipv4 addresses

IPv4 Addresses


Internet protocol which version

Internet Protocol: Which version?

There are currently two versions of the Internet Protocol in use for the Internet

  • IPv4 (IP Version 4)

    • Specified in 1980/81 (RFC 760, 791)

    • Four byte addresses

    • Universally deployed

    • Problem: Address space almost exhausted

  • IPv6 (IP Version 6)

    • Specification from 1998 (RFC 2460)

    • Significant differences to IPv4, but not fundamental changes

    • 16-byte addresses

    • Problem: Not widely used (yet?)


  • Slow adoption of ipv6

    Slow adoption of IPv6

    • IPv6 is available since 15 years, and almost all operating systems now support it

    • But IPv6 is not yet widely adopted

    • Measurements at Internet Exchange Point in Amsterdam:

    linear

    semi-log


    Slow adoption of ipv61

    Slow adoption of IPv6

    • IPv6 is available since 15 years, and almost all operating systems now support it

    • But IPv6 is not yet widely adopted

    • Measurements at Internet Exchange Point in Amsterdam:

    linear


    Ece 461 ipv4 based

    ECE 461: IPv4 based

    We use IPv4 throughout in lecture, labs, and assignment

    IPv6 concepts are discussed in the lecture


    Ipv4 addresses

    IPv4 Addresses


    Ipv4 addresses1

    IPv4 Addresses


    Ip addresses

    IP Addresses

    • An IPv4 address is an address of the Internet Protocol Version 4. When the version is understood from the context we only say “IP address”

    • On the public Internet, an IP address is unique global address of a network interface

    • The IP address is used by hosts and routers for delivery of IP datagrams


    Dotted decimal notation

    Dotted Decimal Notation

    • IPv4 addresses are written using dotted decimal notation:

      • Each byte is identified by a decimal number in the range [0..255], separated by periods (`dots’).

  • Example:

  • 10000000

    1100100

    00001011

    00111100

    1st Byte

    = 128

    2nd Byte

    = 100

    3rd Byte

    = 11

    4th Byte

    = 60

    128.100.11.60


    Structure of an ip address

    Structure of an IP address

    • IP address consists of a network prefix and a host number

      • Network prefix identifies a particular network

      • Host number identifies an interface on the network

  • The delivery of a packet from a sender to the destination proceeds in 2 steps:

    • Use network prefix to deliver packet to the right network

    • Once the network is found, use the host number to deliver packet to the right interface

  • How can you determine the length of the network prefix?

  • network prefix

    host number


    Length of network prefix

    Length of network prefix

    • The length of the network prefix must be provided in addition to the numerical value of the address

    • There are two conventions for indicating the length:

      • Add length of the network prefix to address(“prefix notation”, “slash notation”, “CIDR notation”)

      • Add bitmask of the network prefix in dotted decimal notation (“netmask”)

    32 bits

    network prefix

    host number

    Length of network prefix


    Notation of ip address

    Notation of IP address

    • Example: Suppose the network prefix is 16 bits long

    • Prefix notation: 128.100.11.60/16

    • Netmask notation:128.100.11.60255.255.0.0


    Special ip addresses

    Special IP Addresses

    • IP address of a network

      • Host number is set to all zeros, e.g., 128.100.0.0

  • Broadcast address

    • Host number is set to all ones, e.g., 128.100.255.255

    • Broadcast goes to all hosts on the network

    • The address 255.255.255.255 is a broadcast on the local network

  • Convention for default gateway (but not a reserved address):

    • Default gateway has host number set to ‘1’, e.g., 128.100.0.1


  • Reserved network prefixes

    Reserved Network Prefixes

    • Loopback interfaces:127.0.0.0/8

      • Most systems use 127.0.0.1 as loopback address

      • A host can send a packet to itself by sending it to address 127.0.0.1

    • Link Local Addresses: 169.254.0.0/16

      • Also referred to as auto-configuration

      • When a system cannot acquire an IP address, it selects a random address from the range (it tests whether the address is in use)

      • Packets from this address are not forwarded to other networks

    • Private networks: 10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16

      • Private networks are IP networks that are not part of the public Internet

      • IP addresses need to be unique only within the same private network

        • Systems on different private networks can re-use addresses

      • When packets cross between private network and public Internet, IP addresses in header must be modified


    Network prefix and address block

    Network Prefix and Address Block

    • The IP address of a network has the host number set to 0:

      128.100.0.0

    • Network address with prefix length is called network prefix:

      128.100.0.0/16 or 128.100/16

    • A network prefix is interpreted as a range of IP addresses:

      128.100.0.0/16  128.100.0.0–128.100.255.255

      • A network prefix is also called address block

      • It provides the range of addresses allowed on the network

      • The shorter the network prefix, the larger the address block


    Network prefix length and address block size

    Network Prefix # of IP Addresses

    /321

    /312

    /304

    ……

    /24256

    /23512

    /221,024

    /212,048

    /204,096

    ……

    /1665,536

    ……

    /816,777,216

    ……

    /21,073,741,824

    /12,147,483,648

    Network prefix length and address block size

    • To set up a network of a given size, one needs to acquire a address block with a sufficient number of addresses


    How does one get an ip network address

    How does one get an IP network address?

    • Internet Assigned Number Authorities (IANA) manages the global IP address space.

    • IANA allocates addresses to Regional Internet Registries (RIR)

      • IANA allocates addresses in /8 address blocks

      • All available blocks have been allocated. The last available address block was assigned in 2011

    IANA

    RIR

    LIR(ISP)

    allocates

    allocates

    assigns

    assigns

    End user

    End user


    How does one get an ip network address1

    How does one get an IP network address?

    • RIR allocates addresses to Local Internet Registries (LIR)

      • LIRs are generally Internet Service Providers

      • Block sizes are /20 or larger

    • End users obtain addresses from an RIR or LIR

    • Some countries have National Internet Registries (NIR), which are between the RIR and LIR levels

    IANA

    RIR

    LIR(ISP)

    allocates

    allocates

    assigns

    assigns

    End user

    End user


    Regional internet registries

    Regional Internet Registries

    • There are five Regional Internet Registries, each responsible for managing the address space of a large geographic area

    • Address blocks managed by the RIRs are listed at:

      http://www.iana.org/assignments/ipv4-address-space/ipv4-address-space.xml


    Available ipv4 addresses 9 2012

    Available IPv4 addresses (9/2012)

    • RIRs are running low on IP addresses:

      (one /8 address block ≈16.8 million IP addresses)

    • Current status of remaining IP addresses:

    Source: http://www.potaroo.net/tools/ipv4/index.html


    Ipv4 exhaustion and migration to ipv6

    IPv4 exhaustion and Migration to IPv6

    • The vast majority of IPv4 addresses are used up

       IPv4 exhaustion

    • Adoption of IPv6 is driven by IPv4 exhaustion:

      • There have been numerous predictions of imminent IPv4 exhaustion

      • People have been creative with slowing down IPv4 exhaustion through policies and protocols

      • IPv4 exhaustion will occur gradually, but is increasingly urgent

    • As IPv4 addresses become less available, the use of IPv6 is expected to increase substantially

      • The migration from IPv4 to IPv6 is expected to be a slow transition, lasting a decade or more

      • Until then, IPv4 and IPv6 will co-exist


    Classful ip addresses

    Classful IP Addresses

    • When Internet addresses were standardized (early 1980s), the Internet address space was divided up into classes

    • Three classes available for interfaces:

      • Class A:Network prefix is 8 bits long

      • Class B:Network prefix is 16 bits long

      • Class C: Network prefix is 24 bits long

    • Two additional classes:

      • Class D: Used (multicast) group addresses

      • Class E: Reserved for future use


    Classful ip addresses1

    Classful IP Addresses

    The classes were identified by the bit values of the IP address

    Class A:IP address starts with “0”

    Class B:IP address starts with “10”

    Class C:IP address starts with “110”

    Class D:IP address starts with “1110”

    Class E:IP address starts with “11110”

    The length of the network prefix is implied by the address

    There is no need to provide the length of the network prefix


    Classful ip addresses2

    Classful IP Addresses


    Classful ip addresses3

    Classful IP Addresses

    • We will learn about multicast addresses later in this course

    • Class E addresses have never been released for use


    Ip allocation with classful ip addresses

    IP Allocation with Classful IP Addresses

    • Limited flexibility for obtaining a network address:

      Class C: ≤ 224 - 2 = 254 IP addresses:

      Class B: ≤ 216 - 2 = 65534 IP addresses

      Class A: ≤ 224 - 2 = 16,772,214 IP addresses

    • Too few network addresses for large networks

      27 = 128 Class A networks

      214 = 16,384 Class B networks

    • Flat address space. Routing tables in the backbone Internet need one entry for each network address.

      Class C networks: up to 221 = 2,097,152 entries

      By 1993, the lookup time of routing tables had become a bottleneck for Internet performance


    Ipv4 addresses

    Allocationof Classful Addresses


    From classful to classless

    From Classful to Classless

    • In 1993, there was a major shift for interpreting and allocating IP addresses:

    until 1993:

    ClassfulAddresses

    after 1993:

    Classless Interdomain Routing(CIDR)


    Cidr classless interdomain routing

    CIDR - Classless Interdomain Routing

    • CIDR abandons the notion of classes

    • Key Concept:The length of the network prefix of IP addresses can be any value

    • Consequences:

      • Since the length of the network prefix is no longer implied by the address, the size of the network prefix must be provided with an IP address ( CIDR notation)

      • Hierarchical routing aggregation introduces dependency of IP addresses to service provider

      • Need for new lookup algorithms for routing tables


    Division of ipv4 address space

    Division of IPv4 address space

    00000…00

    Class A

    (231 addresses)

    10000…00

    Class B

    (230 addresses)

    11000…00

    Class C (229 addresses)

    11100…00

    11110…00

    Class D (228 addresses)

    unused addresses

    Class E (228 addresses)


  • Login