A Note On Network Design And Performance

Submitted By hawkfan1985
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Pages: 9

6K190 Network Design and Performance
University of Iowa
Professor: Warren Boe

Lecture Notes: 1/20/2009

Agenda
 Ethernet
 TCP/IP
 DoD

Model
 IP Classes
 Classful Routing

Department of Defense Model (DOD):


AKA – Internet Suite of Protocols



Is TCP/IP



Model and suite of protocols created by Department of
Defense to ensure data communication and integrity in the event of a catastrophic war.

Comparison between DoD, OSI,
& TCP/IP
OSI

DoD

Hybrid TCP/IP OSI

Application

Process/Application

Application

Transport

Host-to-Host

Transport

Network

Internet

Internet

Data Link

Network Access

Data Link

Presentation
Session

Physical

Physical

Process/Application Layer:
Typical Protocols:
Telnet – Terminal Emulation



Access to remote machines and consoles
Appears as though the terminal is connected directly to local device

FTP – File Transfer Protocol:




Transfers files
Somewhat secure
Allows directory/file manipulation (move, delete, creates, navigate structure)

TFTP – Trivial File Transfer Protocol:


Stripped down version of FTP



No security



Need to know exactly where files are located (no navigation) NFS – Network File System: 

Created by Sun Microsystems



Transfer of files between disparate systems (i.e. UNIX and Novell or Microsoft)

SMTP – Simple Mail Transfer Protocols:


Spooled email transmission system



SMTP – sending mail



POP – receiving mail

LPD – Line Printer Daemon:


Remote printer sharing (UNIX/Mainframe)

X Windows:


GUI interface to remote system (UNIX Server).

SNMP – Simple Network Management Protocol:


Collects valuable network information (statistics, results and informational messages)



Baseline monitoring



Traps – Warnings

DNS – Domain Name Services:


Resolves DNS Names to IP address



FQDN – Fully Qualified Domain Name



Hierarchical structure that logically locates a system based on domain identifier.

DHCP – Dynamic Host Configuration Protocol:


Provides IP configuration of workstations/hosts



Dynamic and automatic



An extension of BOOTP



BOOTP – manual and automatic

Host-to-Host Layer Protocols:


TCP – Transmission Control Protocol



UDP – User Datagram Protocol

Transmission Control Protocol:


Connection Oriented and Reliable



Slower, but Bulletproof



Connection Oriented – Virtual Connection



3 – Way connection Handshake



Sequenced – Packets are numbered



Reliable – ACKs and NAKs



Flow Control (Windowing)



Overhead!

TCP Header Fields:


Source Port – port number of the application sending the data



Destination Port – port number of the application receiving the data 

Sequence Number – allows receiving device to put the data
“pieces” back in order. Acknowledgement Number – defines which packet(s) are expected next.



Offset – lets the receiving device where header stops and data begins. 

Reserved – not used, always set to 0.



Code Bits – controls various functions and is used to setup and terminate sessions.

TCP Header Fields (continued):


Window – identifies the amount of data the sender is willing to accept.



Checksum – CRC error detection on both header AND data. 

Urgent Pointer – who cares!



Option – options and padding (0 bits in size or 32).



Data – the actual data being sent.



Whew!!!

User Datagram Protocol:


Connectionless Oriented and Unreliable (in comparison to TCP)



Fast and Unreliable



Best Effort delivery



Subsequence – no sequence numbers



Unreliable – no ACKs and NAKs



Connectionless – no virtual circuit, no handshaking



No Windowing or Flow Control



Low Overhead



Examples:
NFS
SNMP
Which protocol is used (TCP or UDP)? It’s up to the application developer.



UDP Header Fields:


Source Port – port number of the application sending the data 

Destination Port – port number of the application receiving the data



Length of Segment – Length of UDP header and UDP data fields. 

Checksum –