Download - Protocols
Network Protocols
Dean (3rd), Chapter 4
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
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: TXT=27472 bytes) (Status: PROPOSED STANDARD).
• Not all RFCs are serious--include poetry (1121) and April fools jokes (1605, 2795)
TCP/IP and OSI
Applications
Presentation
Session
Transport
Network
Data Link
Physical
Transport—TCP, UDP
Internet—IP, ARP, ICMP
local network protocol
ApplicationsTelnet, FTP, TFTP, NTP, PING,
BOOTP, DHCP, HTTP
TCP/IP Model OSI Model
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
app
TCPsegment
IPdatagram
LANframe
. . bits . .
app
TCPsegment
IPdatagram
LANframe
TCP Segment Connection oriented: ports, handshaking Provides reliable delivery of data: sequence, checksum, ack
• Source port—port number at source node• Destination port—port number at
destination node• Sequence number—segment’s position in
stream of data• ACK number—used to acknowledge
receipt of segment• Header length—number of 32-bit words in
header• Reserved for later use—no used• Flags: Urgent, ACK, no buffering, reset,
synchronization, last segment• Window size—receivers buffer size• Checksum—used to determine corruption• Urgent pointer—DoD field pointer• Options and padding—complete header
Source Port Destination Port
Sequence Number
Acknowledgement
Window Size
Checksum Urgent pointer
PaddingOptions
Data
flagsLng Rsv
Establishing TCP Connection(Handshaking)
• Request for connection
• Acknowledge connection
• Response
• Connection established
SYN
SYN/ACK
ACK
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
IP Datagram
Connectionless Addressing and routing
• Version—IPv4 or IPv6• Header length• Services—priority info for router• Total length in bytes• Identification—message ID• Flags—is message fragment• Fragment offset• Time to live—number hops left• Protocol—TCP or UDP• Header checksum• Source IP address• Destination IP address• Options—routing/timing info• Padding—fill out multiple 32-bits• TCP (or UDP) segment
Identification
Total Length
Header Checksum
Source IP Address
Destination IP Address
Data – TCP or UDP Segment
Services
Padding
ProtocolTTL
Options
Flgs
Vers IHL
Frag. offset
ICMP
Internet Control Message Protocol Used to control message transfers
• Handshaking
• Report success or failure of packet transfers
• Announces TTL delivery errors
• Troubleshooting information
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
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)
IPv4 Notation
IP addresses are bit patterns IPv4 uses hexadecimal or dot notation to
specify four bytes in address Dana’s IP address:
• 86 72 8A 02 – hexadecimal
• 134.114.138.2 – dot notation “nslookup” utility for looking up IPv4
address
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
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
Assigning IP Addresses
Each node must have unique IP address Static IP assigned manually or with script Dynamic IP assigned
• BOOTP—assigns based on MAC addresses
• Dynamic Host Control Protocol (DHCP)—assigns next available
Sockets and Ports
Transport layer function Port: number associated with process on
machine Socket: combination of IP address and
port• Dana telnet: 134.114.138.2:23
• CBA Web: 134.114.80.216:80
Commonly Known PortsPort Number Process
NameProtocol Used Description
7 ECHO TCP and UDP Echo
20 FTP-DATA TCP File transfer data
21 FTP TCP File transfer control
23 TELNET TCP Telnet
25 SMTP TCP Simple Mail Transfer Protocol
53 DNS TCP and UDP Domain Name System
67 BOOTPS UDP Bootstrap Protocol Server
68 BOOTPC UDP Bootstrap Protocol Client
69 TFTP UDP Trivial File Transfer Protocol
80 HTTP TCP and UDP World Wide Web HTTP
101 HOSTNAME TCP and UDP NIC Host Name Server
110 POP3 TCP Post Office Protocol 3
143 IMAP TCP Internet Message Access Protocol
161 SNMP UDP Simple Network Management Protocol
179 BGP TCP Border Gateway Protocol
444 HTTPS TCP Secure implementation of HTTP
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
DNS Domain Name System (DNS)—converts
between FQN and IP address Domain names—used 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
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
TCP/IP Applications
Telnet – remote terminal application FTP – file transfer TFTP – trivial file transfer NTP – network time protocol PING – Packet INternet Groper
Other Protocols
IPX/SPX – Novell NetBIOS and NetBEUI – Microsoft WINS – Windows Internet Naming
Service – handles NetBIOS name to IP address conversion
AppleTalk – Apple
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
Questions?