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Ch1. Protocols and Architecture
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1.1 Protocols
Used for communications between entities in a system
Must speak the same language
Entities
User applications
e-mail facilities
terminals
Systems
Computer
Terminal
Remote sensor
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IDCM Ch1 Protocol and Architecture
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1.2 Protocol Architecture
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IDCM Ch1 Protocol and Architecture
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1.3 TCP/IP Protocol Suite
Dominant commercial
protocol architecture
Specified and extensively
used before OSI
Developed by research
funded US Department of
Defense
Used by the Internet
An Internet According to TCP/IP
TCP/IP considers all of the hosts to be connected to this larger
logical network rather to their individual physical networks.
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IDCM Ch1 Protocol and Architecture
School of Engineering, SBU
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TCP/IP and OSI
TCP/IP and the OSI Model
Encapsulation
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IDCM Ch1 Protocol and Architecture
School of Engineering, SBU
TCP/IP Protocol Architecture
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 Application Layer
 Communication between processes or applications
 End to end or transport layer (TCP/UDP/…)
 End to end transfer of data
 May include reliability mechanism (TCP)
 Hides detail of underlying network
 Internet Layer (IP)
 Routing of data
 Network Layer
 Logical interface between end system and network
 Physical Layer
 Transmission medium
 Signal rate and encoding
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IDCM Ch1 Protocol and Architecture
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1.3.2 Network Layer
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IP Datagram
variable-length packet (up to 65,536 bytes)
two parts: header(20-60 bytes) and data
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1.3.3 Addressing
Physical address: local jurisdiction, easy to change.
Internet address: universe jurisdiction, cannot change.
Internet Address
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IP Addresses in Decimal Notation
Class Ranges of Internet Addresses
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Nodes with more than one address
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1.3.4 Subneting
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Two Levels of
Hierarchy
Three
Levels of
Hierarchy
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Addresses with and without Subnetting
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Masking
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Example. Find the class, netid and hostid for each address:
Class
Netid
a. 4.23.145.90
A
4
b. 227.34.78.7
D
N/A
N/A
c. 246.7.3.8
E
N/A
N/A
d. 129.6.8.4
B
129.6
8.4
e. 198.76.9.23
C
198.76.9
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Boundary-Level Masking
IP Addr:
Mask
Subnet addr:
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Hostid
23.145.90
Nonboundary-Level Masking
45. 23. 21. 8
213. 23. 47. 37
255.255. 0. 0
255.255.255.240
45. 23. 0. 0
213. 23. 47. 32
Bit-wise AND
IDCM Ch1 Protocol and Architecture
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1.3.5 Other Protocols in Network Layer
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ARP:
find physical address
from IP address
RARP: find IP address from physical address.
ICMP: send notification back to the sender
IGMP: identify the hosts that are members of a group.
Unicasting
Multicasting
Broadcasting
One-to-one
one-to-many
one-to-all
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1.3.6 Transport Layer TCP and UDP(User Datagram Protocol) 14
IP: host-to-host, deliver a packet
from one physical device to another
TCP: port-to-port, (Buffer used by a
particular process)
IP addr: 32 bits-- in IP datagram
Port Addresses
Port addr: 16 bits—in TCP datagram
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IDCM Ch1 Protocol and Architecture
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UDP
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UDP Datagram Format
UDP only provides basic functions:port addr, checksum, length.
It does not provide any sequencing or reordering functions, can not
specify the damaged packet
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IDCM Ch1 Protocol and Architecture
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TCP Segment Format
TCP is a reliable stream transport
port-to-port protocol.
TCP generates a virtual circuit
between sender and receiver that
is active for the duration of a
transmission.
connection establishment and
connection termination alert.
Sequence number. position of the data in the original data stream.
Header length (HLEN): 4 bits, TCP head length:20—60 bytes
Control(6 bits) :independently.
Window size: size of the sliding window used in ARQ.
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1.4 Application Layer
1.4.1. Client-Server Model: (many-to-one)
Client:a program running on the local machine requesting service from a
server. A client program is finite.
Server: a program running on the remote machine provides services to the
clients. A server program is infinite.
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1.4.2 BOOTP and DHCP
Attach to a TCP/IP internet, must know:
Its IP address, its subnet mask, the IP address of a router and the IP address of a
name server which stored in a configuration file.
BOOTP: provide information for a diskless or first time boot computer.
DHCP: provide dynamic configuration. Moving, temporary IP addr.
1.4.3 Domain name system(DNS) – map name and address
Generic Domains: first level 7 possible 3-character labels: com, edu, gov, int,
mil, net, org. a few more labels have been proposed: arts, firm, info,
nom(personal nomenclatures), rec(recreation), store, web.
Country Domains: 2-character country abbreviations.
Inverse Domain: used to map a address to a name.
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IDCM Ch1 Protocol and Architecture
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1.4.4 TELNET
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Remote Login
Network Virtual Terminal(NVT):universal interface between
different OSs.
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1.4.5 File Transfer Protocol
(FTP)
Two connections (Date, Control).
Which use different strategies and
different port numbers.
1.4.6 Trivial File Transfer Protocol (TFTP) – copy files
1.4.7 Simple Mail Transfer Protocol (SMTP)
•User Agent (UA)
•Mail Transfer Agent (MTA)
•Relaying
•Mail gateway
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Figure 25-16
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The Entire E-mail System
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Multipurpose Internet Mail Extensions(MIME)
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SMTP: ASCII format
MIME: extend SMTP to non-ASCII
Post Office Protocol (POP) – download
mail from server
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1.4.8 Hypertext Transfer Protocol (HTTP) -- www
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HTTP Transaction
Uniform Resource Locator (URL): method, host, port, path
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PDUs in TCP/IP
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Some Protocols in
TCP/IP Suite
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Exercise: A site with a given network address and mask. The administration
has divided the site into several subnetworks. Choose appropriate
subneaddresses, host addresses, and router addresses
(a)
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(b)
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Solutions
(a)
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IDCM Ch1 Protocol and Architecture
(b)
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