Transcript Networking concepts and hardware

Networking concepts and
hardware
Basic Communications Model
Standards are needed at all Layers
User Layer
Application Layer
Computer (Transport) Layer
Transmission Layer
Subnet Layer
Station B
Station A
2
2
1
1
4
3
Transmission of Messages
1. Within a Single Subnet, or
2. in Point-to-Point Links Between Subnets
Internet Layer
Station B
Station A
2
1
4
3
Routing of Messages
Across multiple subnets in an internet
Internetting
Station B
Station A
2
1
4
3
internet: collection of subnets such that any station
on any subnet can communicate with any other
station on any other subnet simply by giving the
internet address of the other station.
Layering in Major Architectures
Basic Model
TCP/IP
IPX/SPX
OSI
Application (7)
Application
Application
Application
Presentation (6)
Computer
(Transport)
Transport:
TCP, etc.
Complex:
SPX, etc.
Internet
Internet
Internet
Subnet
(OSI)
Subnet
(OSI)
Subnet
(OSI)
Session (5)
Transport (4)
Network (3):
Internet &
Subnet
Data Link (2)
Physical (1)
LANs, MANs, & WANs
 LAN
– Local area network
– Single office, building, campus
– 10 Mbps to 100 Mbps to the desktop common
– 1 Gbps coming
 Will carry most traffic, because most traffic is
local
PC Networking on a small LAN
Each client and server needs a NIC
rather than a modem
Network Interface
Card (NIC)
In each PC
LANs, MANs, & WANs
 WAN
– Wide area network
– Intercity, international
– 9,600 bps to 1 Mbps common to the desktop
– Links with higher speed are usually shared
(multiplexed) by several desktops
 Emerged before LANs, due to high cost of long-
distance telephone charges
Microsoft Layered Network
Architecture
7. Application
User Mode
6. Presentation
Kernel Mode
NetBIOS driver
5. Session
4. Transport
3. Network
Redirectors
Servers
Transport Driver Interface
WinSock driver
Streams
Transport Protocols
2. Data Link
LLC
MAC
1. Physical
NDIS Interface
Streams
Network Adapter Card Drivers
Network Interface Card
Some basic concepts

NDIS Interface: Network Driver Specification Interface, wraps
NIC drivers and allow communication with multiple protocols,
binds a NIC to a protocol.

Streams: multiple channels allowing broader bandwidth for data
transfer, envelop the protocols.

Transport Driver Interface: allows software drivers (server,
redirector, etc) to communicate with protocols.

Redirectors: software in WS that redirect network drives,
printers requests to network I/O requests.

Servers: software that allows a device to accept requests from
other devices.
Standard protocols
 NetBEUI - NetBIOS Extended User Interface, “native”
Windows protocol, not routable.
 TCP/IP - implemented through WinSock, routable,
supports SNMP, DHCP, WINS.
 NWLink (IPX/SPX) - used to connect to Novell
NetWare, just a protocol, not access.
 DLC - Data Link Control, used to connect to IBM
mainframes and HP printers directly connected to a
network (server).
Data Link Layer
OSI
Data Link
Layer
(Layer 2)
OSI
Physical
Layer
(Layer 1)
Logical Link Control Layer
Media Access Control (MAC) Layer
802.3
802.3
10Base-T 10Base-5
802.3
Other
Physical
Layer
802.5
Physical
Layer
4 Mbps
802.5
Physical
Layer
16 Mbps
Other
Physical
Layer
OSI Data Link Layer is subdivided into two layers
Media access control
Logical link control
LAN Using Ethernet 10Base-T
10Base-T Hub (Multiport Repeater)
Unshielded Twisted Pair (UTP) Wiring
(4-Pair Bundle)
PC
RJ-45 jacks
10Base-T
UTP Wiring
Bundles:
4 Pairs
EIA
Category
3, 4, or 5
Network
Interface
Card
NIC
RJ-45
Jack
NICs
 Network Interface Cards
– Implement Physical Layer
– Plug and Electrical Signaling
– Implements the Data Link Layer (data packaging,
access control, etc.)
– LLC (802.2)
– MAC (802.3 MAC)
Wiring
 Unshielded Twisted Pair (UTP)
– Twisted several times per foot to reduce
interference, T in 10Base- and Unshielded
– No protection except for plastic coating
– Distance limitation: 100 meters (attenuation, distortion, noise and
interference, crosstalk) -- propagation
 Categories of UTP Wiring
– Category 5: The best. Good for 100 Mbps
– Category 3 and 4: lower. May be OK for 100 Mbps
 Wiring Plugs: RJ-45 Standard
– Similar to home (RJ-11) jacks, but wider
CSMA/CD Media Access Control
 CD:
Collision Detection
– If two stations transmit at once ….
– Their signals collide, scrambling one another
– Because each sender listens (senses the carrier),
both know that there has been a collision
– Both stop and wait a random amount of time.
101010
001110
X
Collision
Ethernet 10Base-T LAN with Multiple
Hubs
Hub 2
Hub 3
Hub 1
UTP
Wire
UTP
Wire
Station
A
Station
B
UTP
Wire
UTP
Wire
Hub 4
Daisy chain,
no Loops
allowed!
Maximum distance
between farthest Stations is
4 Hubs/5 100 meter segments
Station
C
UTP Wire
Station
D
Switches
With a switch, multiple
stations may transmit
simultaneously: no
congestion as traffic
grows.
Station
A
Station
B
Switch
Station
C
Connection 1
A-C
Connection 1
A-C
Connection 2
B-D
Connection 2
B-D
Station
D
Wireless LAN
Broadcast
Signal
Transceiver
Transmitting
Wireless LAN
Transceiver
Receiving
Antenna
Cluster
Transceiver
Receiving
Hub Controller
Wireless LAN with Access Points
Access Point
Industry
Standard
Coffee
Cup
Antenna
(Fan)
Wireless
Notebook
NIC
PC Card
Connector
To Ethernet
Switch
802.11 Wireless LAN Speeds

802.11

802.11b

802.11a

802.11g
2 Mbps (rare)
2.4 GHz band (limited in bandwidth)
11 Mbps,
2.4 GHz
3 channels/access point
54 Mbps,
5 GHz (> bandwidth than 2.4 GHz)
11 channels/access point
54 Mbps,
2.4 GHz
limited bandwidth
Addresses

Ethernet address (MAC address )
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
48-bit unique addresses hard wired in NICs (280 trillion)
12 hex numbers, e.g. 00-A0-C9-9F-00-07
first three identify company, Intel in the example
how to see: IPconfig, or System Information
IP address (number)



32-bit value, not hard coded (4 billion), assigned manually or by
DHCP
four dotted quads, each quad a decimal from 0-255,
corresponding to eight bits, e.g. UBMAIL IP address is
198.202.0.25
to convert open Calculator select View, Scientific, decimal and
type dotted quad decimal value, then select binary.
Interneting

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Station A wants to send message to station D, but IP number is not in
the same subnet -- no can do!
Sends the message to the default IP router -- default gateway
All stations belonging to the same subnet share the first three dotted
quads.
204.52.128.67 and 204.52.128.147 are in the same subnet, while
198.202.0.25 is not.
A,B and C-Class Networks

A-class networks
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
B-class networks

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
first 8 bits fixed, from 0-126 (only 127)
very large companies like IBM, BBN, DEC,HP
can assign 3 dotted quads - up to 16 million hosts
first 16 bits fixed, first quad 128-191 and second 0-255 (16,384)
Medium-sized companies like Microsoft, Exxon
can assign 2 dotted quads - up to 65,535 hosts
C-class networks


first 24 bits fixed, first quad 192-223, second and third 0-255
(2,097,152)
can assign 1 dotted quad - up to 253 hosts, 0 is the subnet address., 1
default router address, 255 broadcast address.
Sockets and WinSock
 Sockets are the basic TCP requirement
 Socket address


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IP address of the receiver
Port number of the receiving program (80,21,23)
Type of port TCP or UDP
 WinSock is an adaptation of sockets to the
PC


it now comes as part of the PC OSs
it is an application programming interface
Internet Host Names
 Host names in Windows


HOSTS - a list of IP and names (each machine)
DNS - a server with a common table of IP & names (use with
Windows 2000, together with Active Directory)

WINS - Windows Internet Name Server
not DNS compatible (use only with NT/9x)
 can resolve IP addresses inside a Windows network
 good with dealing with NetBEUI names

 FQDN


Fully Qualified Domain Name
name of a host like: machine.org.domain, e.g.
ubmail.ubalt.edu, with a DNS assignment to an IP
Setting static IP addresses
Open Control Panel and select Network Connections
 Under LAN or High-Speed Internet select local area
connection,
 right-click and select properties
 select Internet Protocol (TCP/IP) and click on properties
 fill in IP number, Subnet Mask, Default Gateway and
DNS server
 click OK, close.
 Use ping to test your setup.
