SUBNETTING AND IP ADDRESS TROUBLESHOOTING

 SUBNETTING:

It is also called sub networking. It is a process through which a very large complex network is sub divided into smaller parts and each such part is known as subnet or sub network.

Benefits

Ø    Reduce network traffic load

Ø    Easy to manage and troubleshoot

Ø    More chances of expansion

192.168.10.0./26          this is class C network address.

1.    identify the valid no. of subnets

§       2ⁿ

§       Where n is the no. of the borrowed bits

§       In above case subnet is 26 bit i.e. 2 borrowed bits for class C it must be 24.

2.    identify valid no. of hosts for each subnet

§       2^m-2

§       Where m is remaining host ID portion bits.

§       Here 2 bits are borrowed and remaining bits are 6.

§       So 2⁶-2=62

3.    identify the value of new subnet mask and the range

§       255.255.255.11000000

§       255.255.255.192

§       Range

·       256-192=64

·       Maximum possibilities of octet-value of host ID.

4.    identify all the valid subnets

§       192.168.10.0

§       192.168.10.64

§       192.168.10.128

§       192.168.10.192

5.    identify all the valid hosts

§       1-62 hosts

§       65-126

§       129-190

§       193-254

6.    identify the broadcast address for each networks

§       192.168.10.63

§       192.168.10.127

§       192.168.10.191

§       192.168.10.255

IP ADDRESS TROUBLESHOOTING

Statement

We have networks in which there are two routers are R1 & R2. both are connected with huge networks

The address of the serial interface of R1 is 20.1 and R2 is 20.2

The address of the Ethernet interface of R1 is 10.2 and R2 is 30.1

Client of R1 having IP 10.1 and client of R2 is 30.2

Case 

 Client 10.1 is not able to communicate with server 30.2 of the other networks.

Step to diagnose the problem

1.    ping 127.0.0.1 if there is a reply means that TCP/IP stack is o.k. and is not corrupt but if there is no reply means TCP/IP protocol stack is corrupt and you have to reinstall the operating system.

2.    if the first step is successfully then try to ping the IP address of PC LAN card if there is a reply means LAN card is O.K. but if there is no reply means LAN card is faulty replace or repair it. We can do repair by right click on the LAN card. It will release the cache memory. Sometime the cache memory is full and card does not work properly.

3.    if the first two steps are successfully then try to ping. The IP address of router Ethernet port i.e. default gateway, if there is reply it means there is no problem in the local LAN physical topology. If it does not reply then problem is with cables, hubs or switch part or router Ethernet port. Problem id with physical topology.

4.    if the first 3 steps are successfully then try to ping the remote server once again if there is no reply its means problem is with the remote site ask the remote site administrator to follow the above 3 steps to trace the problem.

a.     If there is a reply its mean communication takes place it means everything is o.k. and fine.

b.    If there is no communication it means problem is with ARP and DNS servers.