Network Basic Lecture 2

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    Cisco Network Academy
    One Cable Network and Collision
    Cable

90% of Network Failures are in Physical Layer (Cable, Power, NIC)

Physical, Data link, Network Layer

Layer	Contents
Physical	Cable, Binary signal
Datalink	Frame of bytes, Physical Address (Mac Address)
Network	Packet of bytes, Logical Address (IP Address)

Transportation Analogy

   People    == Packet (Network Layer)
   Train/Car == Frame  (Datalink Layer)
   Rail/Road =- Physical layer

Physical Address, Logical Address

Local Destination Address of the Physical Layer

   Name of Railway Station 
   MAC Address (Physical Address)
       (MAC - Media Access Controller = NIC -- Network Interface Card)
   Unique in Worldwide (48bit)

Worldwide Destination Address of the Network Layer

   Name of Destination ( transport independent )
   IP Address (Logical Address)
       (IP -- Internet Protocol)
   Unique in Worldwide (32bit)

Network Address, Host Address, Port

   a pair of IP address (32bit) + Port number (32bit) determines a connection
   IP address contains 
       Network Address  (a kind of transportation (Car/Train)
       Host Address     (an address of station in a transportation)
   Port
       input/output in a host ( final meeting person in the destination )

Bit pattern of a packet, OSI layer

Structure of IP Address

   IP address =  32bit pattern
      =  Network  +  Host
          n bit       32-n bit

class IP address

number of bit of Network part

CLASS A (8 bit)

	1-127

CLASS B (16 bit)

	128-192.0-255

CLASS C (24 bit)

	193-223.0-255.0-255

etc. 224 multi-cast

Private Network (Not world wide)

	192 (Class B), 10 (Class A)

Special host name

        all 0  ... represents network itself
        all 1  ... represents broadcast (for all hosts in the network)

Question:

	Number of hosts in a Class A?
	Number of hosts in a Class B?
	Number of hosts in a Class C?
	Number of networks in a Class A?
	Number of networks in a Class B?
	Number of networks in a Class C?

Question:

	What happens if private address is spilled in the Internet?

Gateway address (Default router)

Special address for a gateway to the Internet.

Hierarchical Network Structure

Example:In a middle sized company which has 3 divisions. There are 30, 50 and 100 computers for each division.

Example:In a university which has science division, engineering division and literate division. Each division has 4 faculties. Each faculty has 20 to 400 computers.

Question:

Select suitable network class for the examples (considering future expansion). Continuous Class C can be used.

Use hierarchical sub networks. There is a gateway for each subnet.

An IP network can be divided into several subnets.

An IP network is separated by network part and host part by net mask.

Designing Network (and subnet)

Binary decimal conversions. (Difficult for most people?)

Try Excel program.Compute by Excel

Class B address division

Q1. 8way division

    1)subnet mask
    2)8 network address 
    3)8 broad cast address

Q2.

Divide 192.168.1.0 by 32 x 4+16 x 8.

Use this kind of table (or Excel).

Q3.

Class B case

Divide 131.15.0.0 by 256. We can use 131.15.48.0-131.15.63.0.

Show the Netmask.

Show the Broadcast Address.

Try this kind of table (or Excel).

Q4.

Class B case

Divide 131.15.0.0 by 64.

Show the Netmask.

Show the Broadcast Address.

Show the IP address of 30th host in the first network.