Network Protocols

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Network Protocols

• Dean (3rd), Chapter 4

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Protocols

• Rules that govern network communications
• Voluntary
• Standards organizations
• IETF Internet Engineering Task Force
• ICANN Internet Corporation For Assigned Names
  and Numbers
  
• ISO Information Technology Committee

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TCP/IP

• Provides suite of conventions and utilities used
  on Internet
  
• Transmission Control Protocol (TCP)
• Internet Protocol (IP)
• Governed by voluntary compliance with Requests
  for Comments (RFCs)
  
• RFC 1 issued 7-Apr-1969 on Host Software by Steve
  Crocker of UCLA
  
• Latest RFC 3994 Indication of Message
  Composition for Instant Messaging. H.
  Schulzrinne. January 2005. (Format TXT27472
  bytes) (Status PROPOSED STANDARD).
• Not all RFCs are serious--include poetry (1121)
  and April fools jokes (1605, 2795)

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TCP/IP and OSI
TCP/IP Model
OSI Model
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TCP/IP Data Encapsulation

• TCP
• Segments and sequences data
• Determines ports
• IP
• Packages segment in datagram
• Determines logical addresses
• Local network protocol
• Creates transmission frame
• Determines physical addresses

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TCP Segment

• Connection oriented ports, handshaking
• Provides reliable delivery of data sequence,
  checksum, ack

• Source portport number at source node
• Destination portport number at destination node
• Sequence numbersegments position in stream of
  data
  
• ACK numberused to acknowledge receipt of
  segment
  
• Header lengthnumber of 32-bit words in header
• Reserved for later useno used
• Flags Urgent, ACK, no buffering, reset,
  synchronization, last segment
  
• Window sizereceivers buffer size
• Checksumused to determine corruption
• Urgent pointerDoD field pointer
• Options and paddingcomplete header

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Establishing TCP Connection(Handshaking)
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UDP

• User Datagram Protocol
• Transport level protocol
• Alternative to TCP
• Connectionless
• Does not assure delivery
• Used for steaming media and other transfers where
  speed is more important than accuracy

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IP Datagram

• VersionIPv4 or IPv6
• Header length
• Servicespriority info for router
• Total length in bytes
• Identificationmessage ID
• Flagsis message fragment
• Fragment offset
• Time to livenumber hops left
• ProtocolTCP or UDP
• Header checksum
• Source IP address
• Destination IP address
• Optionsrouting/timing info
• Paddingfill out multiple 32-bits
• TCP (or UDP) segment

• Connectionless
• Addressing and routing

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ICMP

• Internet Control Message Protocol
• Used to control message transfers
• Handshaking
• Report success or failure of packet transfers
• Announces TTL delivery errors
• Troubleshooting information

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ARP

• Address Resolution Protocol
• Internet (OSI Network) layer protocol
• Maintains table of IP (logical) addresses and MAC
  (physical) addresses
  
• Looks up MAC address using IP address
• Reverse Address Resolution Protocol (RARP) looks
  up IP using MAC

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IP Addressing

• Internet Protocol (IP)
• Internet (OSI Network) layer protocol
• Logical address used by routers
• Each node must have unique IP address
• Two versions
• 32-bit (IPv4)
• 128-bit (IPv6)

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IPv4 Notation

• IP addresses are bit patterns
• IPv4 uses hexadecimal or dot notation to specify
  four bytes in address
  
• Danas IP address
• 86 72 8A 02 hexadecimal
• 134.114.138.2 dot notation
• nslookup utility for looking up IPv4 address

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Special IP Addresses

• Classes
• A 1-126--126 networks and 16,777,214 hosts
• B 128-191-- 16,000 networks and 65,534 hosts
  per network
  
• C 192-223-- 2,000,000 networks and 256 hosts
  per network
  
• IP addresses for private networks
• 10.0.0.0 - 10.255.255.255
• 172.16.0.0 - 172.31.255.255
• 192.168.0.0 - 192.168.255.255
• Reserved IP addresses
• Loopback 127.0.0.1
• Broadcast 255.255.255.255, x.255.255.255,
  x.x.255.255, x.x.x.255
  
• Network use only 0.0.0.0 usually DHCP failed
  to assign address
  
• Network coordination x.0.0.0, x.x.0.0, x.x.x.0

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Subnet Mask

• IP address has network part and host part
• Network part determined by subnet mask
• Class A 255.0.0.0
• Class B 255.255.0.0
• Class C 255.255.255.0
• ipconfig (WinNT) or ifconfig (Unix) display
  subnet mask information

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Assigning IP Addresses

• Each node must have unique IP address
• Static IP assigned manually or with script
• Dynamic IP assigned
• BOOTPassigns based on MAC addresses
• Dynamic Host Control Protocol (DHCP)assigns next
  available

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Sockets and Ports

• Transport layer function
• Port number associated with process on machine
• Socket combination of IP address and port
• Dana telnet 134.114.138.223
• CBA Web 134.114.80.21680

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Commonly Known Ports
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IPv6

• 128-bit (8-bytes) addresses
• Increases number of IP addresses available
• Uses colons () to separate bytes
• Bytes specified using hexadecimal
• dig utility for looking up addresses under IPv6

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DNS

• Domain Name System (DNS)converts between FQN and
  IP address
  
• Domain namesused instead of IP address
• Fully qualified host name
• Network name ucc.nau.edu
• Host name dana
• FQN dana.ucc.nau.edu
• Top-level domains
• arpa, com, edu, gov, org, net, int, mil, biz,
  info, aero, coop, museum, name, pro
  
• ICANN country codes

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Host Files vs DNS

• Host files were used when all nodes on Internet
  were known to all users of internet
  
• DNS has servers dedicated
• Each top level domain
• Each layer below top level domain
• Layers know each other and immediate
  subordinates
  
• Example
• edu domain server knows nau
• nau knows cba and bus.cba
• cba knows all cba and bus.cba nodes

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TCP/IP Applications

• Telnet remote terminal application
• FTP file transfer
• TFTP trivial file transfer
• NTP network time protocol
• PING Packet INternet Groper

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Other Protocols

• IPX/SPX Novell
• NetBIOS and NetBEUI Microsoft
• WINS Windows Internet Naming Service handles
  NetBIOS name to IP address conversion
  
• AppleTalk Apple

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Summary

• Protocols are rules that govern connections
• TCP/IP suite of protocols used by Internet
• TCP Transport layer protocol that segments,
  sequences, and checks data and determines port to
  use
  
• IP Network layer protocol that does logical
  addressing and provides routing information
  
• DNS Domain name system that allows use of names
  rather than IP addresses

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Questions?