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Internetworking and Architecture

Internetworking and Architecture. CST 415. Topics. Definitions Internetworking Internet Addressing The Endians Revisited. Definitions. Application Gateway Message level routing and forwarding is done by a layer of software integrated into the application itself.

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Internetworking and Architecture

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  1. Internetworking and Architecture CST 415 CST 415 - Computer Networks

  2. Topics • Definitions • Internetworking • Internet Addressing • The Endians Revisited CST 415 - Computer Networks

  3. Definitions Application Gateway Message level routing and forwarding is done by a layer of software integrated into the application itself. Network Level Interconnect Messages are delivered from source to destination without the intervention of any end user application programs. • decouples applications from network details. • Intermediate computers know nothing about end user applications. • Topology of networks is flexible. • Network technology can be upgraded without impacting end-to-end application interoperation. Internetworking Detaching application level communications from details of networking technologies and detaching networking technologies from physical transmission technologies. CST 415 - Computer Networks

  4. Internetworking • Provide an economical and fast media for transmission of information. • Provide communication between two arbitrary end points. • Insulate individual implementations from the system as a whole. • Provide a well defined and unified set of communication services. • Allow applications to be distributed across multiple computers in multiple locations. CST 415 - Computer Networks

  5. Internetworking Internetworking is controlled chaos where control is allowed because of careful specification and eventual standardization. The Internet grows unbounded with no global architect. Q: Is the Internet void of problems? Even the best laid plans of mice and men Often go astray And leave us nothing but grief and pain For promised joy - Robert Burns “To a Mouse” (paraphrased) CST 415 - Computer Networks

  6. Internetworking This is a fractal. CST 415 - Computer Networks

  7. Internetworking CST 415 - Computer Networks

  8. Internetworking Internetworking Explanation – From Stallings • See Stallings Figure 8 • See Stallings Figure 9 • See Stallings Figure 10 CST 415 - Computer Networks

  9. Internet Addresses • Internet addresses (IP addresses) are 32 bit addresses. • The bits are organized to optimize routing. • The address is split up into: • Net Identifier : Identify the network on which the host resides. • Host Identifier : Identify the host on the particular network. CST 415 - Computer Networks

  10. Internet Classful Addresses CST 415 - Computer Networks

  11. Internet Classful Addresses • Class A address • 1 bit to identify the class (0 – class A, 1 – class B, C, D, or E) • 7 bits for net ID : There can only be 128 of these in the world. • 24 bits for host ID : Each network can have 16,777,216 host computers. CST 415 - Computer Networks

  12. Internet Classful Addresses • Class B address • 2 bits to identify the class (10 – class B, 11 – class C, D, or E) • 14 bits for net ID : There can be 16,384 of these networks. • 16 bits for host ID : Each network can have 65,536 host computers. CST 415 - Computer Networks

  13. Internet Classful Addresses • Class C address • 3 bits to identify the class (110 – class C, 111 – class D, or E) • 21 bits for net ID : There can be 2,097,152 of these networks. • 8 bits for host ID : Each network can have 254 host computers – 0 == network, 255 – IP Broadcast. CST 415 - Computer Networks

  14. Internet Classful Addresses • Class D address Class D addresses are multicast addresses. 28 bits for these addresses – 268,435,456 addresses available. CST 415 - Computer Networks

  15. Internet Classful Addresses • Class E address Class E addresses are reserved for future use and the bit structure has not yet been defined. CST 415 - Computer Networks

  16. Internet Classful Addresses • Internet addresses do not address the host computer, they address the host-to-network connection. • Specify a host • Specify a computer • A host ID of all zeros is reserved to refer to the network. • A host ID of all ones is reserved for broadcast. • How can the address be used to specify broadcast on a specific network? CST 415 - Computer Networks

  17. Internet Classful Addresses • The use of all zeros in an address field means “this”. • All zeros in a host field means “this” host. • All zeros in a network address means “this” network. • Can be used in the instance that a host does not know the network address. • Hopefully, any reply will have the full network address. CST 415 - Computer Networks

  18. Internet Classful Addresses • Problems • Mobile host machines must be able to change their IP addresses. • What happens to a network when machine #256 needs to be added. • In packet routing, the route taken to a destination host is dependent on the netid. • More on these problems later. CST 415 - Computer Networks

  19. Internet Addresses Dotted Decimal Notation Address: 10000000 00001010 00000010 00011110 is written: 128.10.2.30 CST 415 - Computer Networks

  20. Internet Addresses Class Lowest Address Highest Address A 1 . 0 . 0 . 0 126 . 0 . 0 . 0 B 128 . 1 . 0 . 0 191 . 255 . 0 . 0 C 192 . 0 . 1 . 0 223 . 255 . 255 . 0 D 224 . 0 . 0 . 0 239 . 255 . 255 . 255 E 240 . 0 . 0 . 0 255 . 255 . 255 . 254 The range of dotted decimal values that correspond to each IP address class. Some values are reserved for special purposes. CST 415 - Computer Networks

  21. Internet Addresses Loopback Address: • The loopback address allows the protocol stack to keep a packet destined for the local machine off the network. • This address can be used for inter-process communication using the TCP/IP protocol stack. • The address is 127.0.0.1 • Using this address avoids propagating a packet onto the network hardware. CST 415 - Computer Networks

  22. Internet Addresses Reserved Private Addresses: • 10.0.0.0 to 10.255.255.255 • 172.16.0.0 to 172.31.255.255 • 192.168.0.0 to 192.168.255.255 and as of July 2001 • 169.254.0.0 to 169.254.255.255  CST 415 - Computer Networks

  23. Internet Addresses The IANA (Internet Addressing Number Authority) • Administered by a single person “John Postel” until his death in 1998 • After John died, an organization was formed to administer the addresses. • A new organization was defended to deal with this called ICANN (Internet Corporation for Assigned Names and Numbers) • The job of ICANN is to deal with the assignment of names and numbers in Internet addressing. CST 415 - Computer Networks

  24. The Endians • Network byte order is “big endian” • largest byte in a multibyte item sent first • these bytes read naturally on a piece of paper : left to right. • big-endian is basically every processor type but Intel. • Intel processors are little endian (least significant byte first) • Intel processors must swap bytes when reading data from a standard network connection. CST 415 - Computer Networks

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