Download Protocols - Computing Sciences

Protocols
ITEC 370
George Vaughan
Franklin University
1
Sources for Slides
• Material in these slides comes primarily
from course text, Guide to Networking
Essentials,Tomsho, Tittel, Johnson (2007).
• Other sources are cited in line and listed in
reference section.
2
TCP/IP and OSI Models
TCP/IP and OSI Models (OSI-Model, n.d.) and (Tomsho, 2007)
TCP/IP
Layers
Application
PDU
Data
OSI Layers
7 Application
6
5
Transport
Segments 4
Network
Packets
3
Link
Frames
2
Function
Network process to application,
Initiates or accepts a request to transfer
data
Presentation Adds formatting, display, and
encryption of information
Session
Adds communication session control
information, Login/Logout
Transport
Adds End-to-end connections and
reliability, re-sequencing, flow control
Network
Path determination and logical
addressing (IP), translates MAC
address to logical address
LLC
Data
Adds error checking and physical
Link
addressing (MAC & LLC)
Devices - Apps
Standards
Browsers,
servers,
Gateways
Gateways
HTTP, SNMP,
FTP, Telnet
DNS,
Gateways
Gateways
NetBIOS
Routers
IP, ICMP,
ARP, NetBEUI
Switches,
Bridges, NICs
802.3, 802.11,
FDDI
ASCII, MPEG
TCP, UDP
MAC
Bits
1 Physical
Media, signal and binary transmission, Hubs,
sends data as a bit stream
Repeaters
10Base-T, T1,
E1
3
Function of Protocols
• Protocol = Rules for communication
• Protocols exist for each layer of OSI
model.
• Some protocols span more than one layer.
• Higher layer protocols are more abstract.
• When protocols work together to cover
multiple OSI layers, they are referred to
collectively as a protocol stack (or suite).
4
Connectionless and ConnectionOriented Protocols
• Connectionless
–
–
–
–
No guarantee of delivery
Low overhead, faster
Connections don’t have to be setup or torn down
Rely on upper layers to provide reliable communications
• Connection Oriented
–
–
–
–
Reliable but slower
Receiver sends acknowledgement to indicate successful transfer
Packets are resent in event of error
Upper layers don’t have to worry about reliable transmission
5
Routable and Non-routable
Protocols
• Routable
– Operate at Network layer
– Support internetworks (MAN, WAN)
– Example: TCP/IP
• Non-Routable
– Does not operate at Network layer
– Useful for small LANs
– Example: NetBIOS Extended User Interface
(NetBEUI)
6
TCP/IP and OSI Models
TCP/IP and OSI Models (OSI-Model, n.d.) and (Tomsho, 2007)
TCP/IP
Layers
Application
PDU
Data
OSI Layers
7 Application
6
5
Transport
Segments 4
Network
Packets
3
Link
Frames
2
Function
Network process to application,
Initiates or accepts a request to transfer
data
Presentation Adds formatting, display, and
encryption of information
Session
Adds communication session control
information, Login/Logout
Transport
Adds End-to-end connections and
reliability, re-sequencing, flow control
Network
Path determination and logical
addressing (IP), translates MAC
address to logical address
LLC
Data
Adds error checking and physical
Link
addressing (MAC & LLC)
Devices - Apps
Standards
Browsers,
servers,
Gateways
Gateways
HTTP, SNMP,
FTP, Telnet
DNS,
Gateways
Gateways
NetBIOS
Routers
IP, ICMP,
ARP, NetBEUI
Switches,
Bridges, NICs
802.3, 802.11,
FDDI
ASCII, MPEG
TCP, UDP
MAC
Bits
1 Physical
Media, signal and binary transmission, Hubs,
sends data as a bit stream
Repeaters
10Base-T, T1,
E1
7
TCP/IP Network Layer Protocols
• Internet Protocol version 4 (IPv4 or IP)
– Source and Destination logical addressing, routing
– Connectionless
– Fast but not reliable
• Internet Control Message Protocol (ICMP)
– Used to send error and control messages
– Used by ‘Ping’ utility
• Address Resolution Protocol (ARP)
– Used to resolve logical (IP) address to physical
(MAC) address
– Can only be used for two systems in same network.
8
Example of TCP/IP Network Layer
Protocols
•
•
Computer A needs to send a message to
Computer B
Before computer A can send message, it
needs the following addresses for computer B:
– IP (logical address)
– MAC (physical address)
1. Computer A sends out ARP broadcast message to
all devices.
2. Computer B recognizes IP address in ARP and
sends back MAC address to computer A
3. Computer A now has 2 addresses necessary for
send message to computer B.
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TCP/IP Transport Layer Protocols
•
Transmission Control Protocol (TCP)
–
–
–
Accepts messages of any length from upper layers
Connection-Oriented
Uses 3-way handshake to establish connection
1.
2.
3.
4.
–
–
–
A sends ‘Synchronize’ (SYN) message to B
B sends ‘Synchronize Acknowledgement’ (SYN-ACK) message
back to A
A sends a ‘Forward Acknowledgment’ (ACK) to B
Connection between A and B is now established.
TCP is responsible for fragmenting application into segments
TCP is responsible for reassembling the application data from
segments.
TCP uses Acknowledgment messages to:
•
•
Ensure that data is properly received.
Manage flow control
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TCP/IP Transport Layer Protocols
(Cont.)
• User Datagram Protocol (UDP)
– Connectionless
– Faster, but less reliable than TCP
– UDP itself does not segment application data
– UDP does not use acknowledgements
– UDP is used by some higher layer protocols
such as NFS and DNS.
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TCP/IP Application Layer Protocols
• Domain Name System (DNS)
– Name-to-Address resolution system
– einstein.franklin.edu  65.24.7.3 (try
‘nslookup einstein.franklin.edu’
• Hypertext Transport Protocol
– Web-pages, browsers, servers
• File Transfer Protocol (FTP)
• Telnet
• Simple Mail Transport Protocol (SMTP)
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TCP/IP Application Layer Protocols
Tomsho, Tittel, Johnson (2007)
• DHCP
– Detailed configuration of devices, keeping track of assigned addresses
and to which machine they were assigned, etc., is difficult in large
networks
– DHCP was developed to make this process easier
– DHCP server must be configured with a block of available IP
addresses and their subnet masks
– Clients must be configured to use DHCP
• Broadcast request message is sent on boot
– Client leases the address the server assigns to it
– If no answer is received, in an APIPA-enabled OS, the
computer assigns itself an address (169.254.x.x)
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IP Addressing
• IP addressing is responsible for routing in
TCP/IP environment.
• Example: 192.203.187.0
• IP address is 32 bits long (4 bytes)
• Special IP addresses:
– 255.255.255.255 = Broadcast
– 127.xxx.xxx.xxx = Localhost
• IP address is divided into 2 parts
– Network Identification
– Host Identification
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Scope of Transmission
• Hosts in same network (same Network ID)
can be connected with switches/hubs
• Router is required to transmit to hosts
outside of network (different Network ID).
• Broadcast messages can only be
transmitted to hosts within same network
(broadcast domain).
15
Types of IP Addressing
• The demarcation point in the 32 bit
address between network ID and host ID
depends on addressing scheme:
– Class Based Addressing generally uses a
byte boundary as the dividing point
– Classless Based Addressing uses a bit
boundary.
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Class Based IP Addressing
(Cisco – IP Addressing, n.d.).
Used less frequently now, CIDR preferred
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Internet Protocol Version 6
• Limitations with IPv4
– 32 bit address space is limited
– No Quality of Service (QoS) support
• IPv6 Features:
– Incorporates IPSec
– 128 bit address
– Auto-configuration
• No IP address to assign
• No subnet mask to determine
• 2 methods of auto-configuration
– Stateless
• Host creates its own IP address based on router information
and MAC address
• Simplest and most common
– Stateful
• Relies on DHCP server
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IPv6 Address Scheme
•
•
•
•
Hexidecimal grouped in 16 bit sections:
– 2001:1b20:302:442a:110:2fea:ac4:2b
Leading zeroes are eliminated
2 or more 16 bit fields of all zeros can be ignored:
– 2001:260:0:0:0:2ed3:340:ab (long form)
– 2001:260::2ed3:340:ab (short form)
IPv6 has 3 parts:
Bits # of 16-bit fields
Purpose
Example
48
3
Public Topology Backbone Provider
16
1
Site Toplogy
Business, Local ISP
64
4
Interface identifier Based on MAC address
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Other Protocol Suites
Tomsho, Tittel, Johnson (2007)
• Other protocol suites are sometimes used
on older networks, where the need to
change to TCP/IP is not warranted, or in
environments suited to the suite’s features
– NetBIOS/NetBEUI
• Used primarily on older Windows networks
– IPX/SPX
• Designed for use on NetWare networks
– AppleTalk
• Used almost exclusively on Macintosh networks
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References
Tomsho, Tittel, Johnson (2007). Guide to Networking
Essentials. Boston: Thompson Course Technology.
Odom, Knott (2006). Networking Basics: CCNA 1
Companion Guide. Indianapolis: Cisco Press
Wikipedia (n.d.). OSI Model. Retrieved 09/12/2006 from
http://en.wikipedia.org/wiki/OSI_Model
Cisco – IP Addressing (n.d.). IP Addressing. Retrieved
09/27/2006 from
http://cco.cisco.com/warp/public/701/3.html#figone
IANA (n.d.) Abuse Issues and IP Addresses . Retrieved
11/11/06 from http://www.iana.org/faqs/abuse-faq.htm
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