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COE Chapter 18: Network Layer; IP Addressing - Coggle Diagram

- - - - Packets arriving at an interface are examined for sources & destination addressing.
        Then queued to the appropriate outgoing interface according to their destination address & a set of rules & performance metrics
        
        Rules are encoded in a routing table, that contains entries for all interfaces and their connected networks.
    - - The address space is 2^32 or 4,294,967,296.
      - q) Convert the binary numbers to dotted decimal Ip address
- - - - The address space is divided into five classes: A, B, C, D, and E.
      - A large part of the addresses were wasted
        
        Was replaced with classless addressing
      - IPv4
        
        For IPv4, Default Mask is a 32-bit number that gives the first address in the block (the network address) when ANDed with any address present in the block
        
        The default mask can help us find NetID and the HostID
        
        We can show the mask in /n, known as slash notation or CIDR (Classless Interdomain Routing) notation.
        
        Also used in classless addressing
        
        Default mask for glassful addressing
        
        In APv4 addressing, a block of addresses can be defined as x.y.z.t /n, where x.y.z.t defines one of the addresses and the /n defines the mask.
        
        The first address in the block can be found by setting the rightmost 32-n bits to 0s.
        
        Example.) A block of addresses is granted to a small organization. We know that one of the addresses is 205.16.37.39/28. What is the first address in the block?
        
        Binary representations of the given address is
        
        00010000 00100101 00100111
        
        If we set 32 - 28 rightmost bits to 0, we get
        11001101 00010000 00100101 0010000
        or 205.16.37.32
        
        The last address in the block can be found by setting the rightmost 32 - n bits to 1s.
        
        Example.) Find the last address of the block
        
        Total number of addresses in the block can be found by using the formula 2^32-n
        
        Example.) Find the number of addresses
        
        The value of n is 28, which means that number of addresses is 2^32−28 or 16.
      - Example.) Figure on next slide shows a block of addresses, in both binary and dotted-decimal notation, granted to a small business that needs 16 addresses.
        
        We can see that the restrictions are applied to this block. The addresses are contiguous. The number of addresses is a power of 2 (16 = 2^4), and the first address is divisible by 16. The first address, when converted to a decimal number, is 3,440,387,360, which when divided by 16 results in 215,024,210.
    - - Class A: Unicast address designed for large organizations
        
        NetID is 1 byte, 2^8 networks
        
        HostID is 3 bytes, 2^24 hosts per network
      - Class B: Unicast address designed for midsize organizations
        
        NetID is 2 byte, 2^16 networks
        
        HostID is 2 bytes, 2^16 hosts per network
      - Class C: Unicast address designed for Small organizations
        
        NetID is 3 byte, 2^24 networks
        
        HostID is 1 bytes, 2^8 hosts per network
    - - Notes.)
        
        First address is usually not assigned to any physical host. Its called the Network Address, used to represent the organization to the world
        
        Last addres is not assigned too, its called the broadcast address within that network.
        
        Thus, this makes the number of valid host addresses equal to: 2^(32 - n) - 2
  - - - Intranet
        
        A network belonging to an organization, accessible only by the organizations member, employees, or others with authorization.
  - - - IPv6 address is 128 bits (16bytes) long
- - - - There are 3 levels of hierarchy in the addresses
        
        Subnet ID
        
        Host ID
        
        Network Id
        
        notes:
        
        First address in a subnet is not assigned to any host. It's called the network or wire address, used to represent the organization to the world.
        
        Last address not assigned too, called broadcast address within the subnet
        
        Availible host addresses in the subnet equal to: 2^(32-n) - 2
        
        Example.) What is the network address of a subnet if we know that one of its hosts IP address is 127.16.64.7/28?
        
        Example 2.) What is the broadcast address in a subnet if we know that one of its hosts IP address is 127.16.64.7/28?
        
        Example 3.) An ISP is granted a block of IP addresses starting with 120.60.0.0/16. The ISP wants to distribute these blocks to 100 customers with each needing only 7 addresses. Design the subnets and give the dotted decimal notation for each subnet’s first and last valid host addresses. For practical reasons, the first and last addresses cannot be used as host addresses
        
        Because the ISP is granted /16 block, it has 16 initial host ID bits that it can divide between subnet bits and host ID bits
        
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