Notes on Networking

Comparison of Layers

Internet

 

OSI

 

NT

   

Application

   

Application

 

Presentation

 

File System Drivers

   

Session

   

Transport

 

Transport

 

Transport

Internet

 

Network

   

Network

 

Logical Data Link

 

NDIS

Interface

 

MAC

 

Adapter Drivers

Physical

 

Physical

 

Network Adapter

Internet Protocol

IPX/SPX

NetBEUI

 

IP addresses

Each host has a unique 32 bit internet address.

Network Information Center (NIC) assigns netids.

Class A

0 netid

hostid

Class B

10 netid

hostid

Class C

110 netid

hostid

Class D

1110

multicast address

Class E

11110

Reserved for future use

Because an IP address encodes both network and host, a machine that connects to two networks will have to have two IP addresses.

Special IP addresses:

Because the IP address encodes the network, the IP address must change if the host moves to another network.

 

Subnets

A single Internet Domain (not Windows NT domain) can be partitioned into subnets. Routers or gateways connect separate subnets.

Subnets reduce the amount of broadcast traffic.

The high order bits of the HOSTID are used to identify the subnet. The Subnet Mask can be set to recognize subnets.

example: Consider a class C Internet with 8 subnets. The subnet mask would be

255.255.255.224

in binary this is

11111111.11111111.11111111.11100000

Information needed to implement TCP/IP

Dynamic Host Configuration Protocol

DHCP servers can provide configuration information to computers using the Internet Protocol.

DHCP servers are accessed during initialization.

DHCP can allocate a specific IP address to a machine (based on its Ethernet address) or can select an IP address from a pool.

DHCP helps to centralize network management.

Windows Internet Name Service (WINS)

WINS servers provide the Internet address that can be used to access a specified NetBIOS name.

WINS is optional. Without WINS, a computer will broadcast to find a computer with a specified NetBIOS name.

WINS servers do not need to be initialized with a database of names. WINS clients announce their IP address when they initialize. WINS servers keep track of the names announced.

 

last updated on 01/02/04