Wednesday, November 23, 2011
router cont....
We can use hypertrm command to access the hyper terminal.
Privileged mode commands.
1. Show History
a. it is used to see the previous 10 commands being used over the router till router powered up to privileged mode.
2. show terminal
a. It is used to see the size of history.
3. terminal history size 20
a. This command is used to change the size of history.
4. show version
a. it is used to see
i. version of router’s IOS (Internetworking Operating System)
ii. Size of RAM, NV RAM and flash memory
iii. Number and type of interfaces.
iv. Configuration registered value.
5. show interfaces
a. it is used to see
i. name of the interface
ii. status of the interface
iii. IP of the interface
iv. MAC address of the interface
v. M.T.U. i.e. 1500 bytes (Maximum Transmission Units)
vi. Receiving load Rx load
vii. Transmission load Tx load
viii. Reliability
ix. Load
x. Delay
xi. Encryption type
NOTES
By default encapsulation over the router’s Ethernet port is ARPA (Advanced Research Project Agency) and over the serial port is HDLC (High Level Data Link Control)
6. show interface interface name
a. It is used to see the above specified detailed information relating to any specific interface.
7. show startup-config
a. This command is used to see the startup configuration of router.
b. It will view
i. The IP assigned to interface
ii. Enable password
iii. The password of lines
8. erase startup-config
a. this command is used to erase the startup configuration.
9. show running-config
a. It is used to see the last changed but not saved configuration i.e. running configuration.
10. show IP interface brief
a. This command is used to view layer three related information. It will view info about interfaces like name IP address, working, line protocol, port status.
11. show protocols
a. This command is used to view the detailed information of routing protocol.
12. show ip protocols
a. this command is used to view the information about the configure routing protocol
13. show IP route
a. This command is used to view the routing table.
14. show arp
a. This command is used to see the Ethernet interface.
15. clear arp
a. This command is used to clear the arp table.
16. show hosts
a. This command is used to see the host entry in the host table.
17. ip host ip address hostname
a. This command is used to make a host entry into the host table.
18. copy running-config startup-config
a. This command is used to save the running configuration to startup configuration in other word we can save the running configuration as the startup configuration.
b. There is another way to save the running configuration as
i. Write running-config startup-config
ii. Write
19. copy startup-config running-comfit
a. This command is used to recover the password.
Global configuration mode command.
20. hostname <name>
a. This command is used to assign the hostname to the route. If the name is not set then by default it is router.
21. config-register
a. This command is used to change the value of router’s config register.
b. Interface configuration mode abc (config-if)#
22. IP address 10.0.0.1 255.0.0.0
a. This command is used to assign IP address.
23. no shutdown
a. This command is used to up the port or interface.
24. shutdown
a. this command is used to down the interface or port
25. line configuration mode
a. abc(config-line)#
b. password
c. login
26. global mode (how to set the password)
a. router (config)# enable password abc
i. to create plain enable password for privileged mode
b. router (config)# enable secret abcd
i. To create enable secret password. I.e. in encrypted form.
Privileged mode commands
27. show IP interface
a. This command is used to see the layer three related information regarding all the interfaces.
28. show IP interface brief
a. This command is used to see the brief layer three information which includes
i. Name of the interface
ii. Status of the interface
iii. State of the interface
iv. IP address of interface
29. show startup-config
a. This command is used to see the startup configuration or saved configuration of your router.
30. show running-config (run)
a. This command is used to see the running configuration i.e. the configuration which is used to run the router but it is not saved in the NVRAM.
31. show controller <serial interface name)
a. It is used to see weather the serial cable slot attached to your router is either D.T.E. or D.C.E.
32. reload
a. It is used to restart the router.
33. copy run start
a. This command is used to save the running configuration into startup configuration. Or to permanently save router configuration.
34. copy start run
a. this command is used to save the startup configuration into your running configuration.
Line configuration mode
35. password
a. This command is used to set password over the specific line.
36. login
a. it is used to activate a line for access by the user.
Global configuration mode
37. hostname
a. it is used to change or set the name of the router.
38. enable password
a. it is used to set or change the router simple enable password.
39. service password-encryption
a. this command is used to encrypt all the password of your router.
b. Once encrypted these password can never be get decrypted.
40. enable secret
a. this command is used to change or set the secret password. This password is like the simple password but it is in the encrypted form.
Interface configuration mode
41. IP address 10.0.0.1 255.0.0.0
a. This command is used to change or set the IP address of any specific interface
42. no shutdown
a. this command is used to manually change the status of an interface from down to up.
43. shutdown
a. this command is used to manually change the status of an interface from up to down.
44. clock rate 64000
a. this command is used to set the clock rate over the serial interface where DCE cable is attached. (we can use the command show controller to see the DCE end.)
45. description
a. this command is used to set description over any interface of a router.
Notes
When a password is set as enable password this password is over the privileged mode. I.e. if you want to enter in the privileged mode then you must have this password.
When a password is set over the console wire then this password is entered to enter in the user execution password.
Commands are
· Line console 0
· Password (password name)
· Login
46. show flash
a. This command is used to see the content of the flash.
47. show clock
a. this command is used to see the router clock.
Password
To make a password on the console line we can write a command as
Line console 0
Password (password)
Login
We can make a password on the privileged mode by enable command as enable password or enable secret
Troubleshooting
Configuration register
It is a hexadecimal value that specifies the router from where to load the IOS.
0x2100
Ø This value specifies the router to load the IOS form the flash into the RAM.
Ø It will break the booting sequence of the router.
Ø Router will go into the rommon (ROM MONITOR) mode.
Ø This mode is used to troubleshooting, maintenance and repair of the router
Ø The commands used in this mode are different from the router normal mode.
Ø In 2500 series only > sign mean that we are in the rommon mode.
Ø In 2600, 3600, 1700 rommon > is appear when we enter into the rommon mode.
Ø To enter into rommon mode we can use the key combination as ctrl + break.
0x2101
Ø This value specifies the router to not load the IOS from flash to RAM.
Ø This value specify the router to boot from mini IOS which is present in the ROM.
Ø In case of 2500 the command prompt is as router(boot)>
Ø In case of 2600,3600,1700 the command prompt is as router>
0x2102
Ø This is the default value for each router
Ø This value specifies the router to load IOS from the flash to RAM and then load the startup configuration (saved configuration) from the NVRAM.
Ø The command prompt in this mode is router>
0x2142
Ø This value specifies the router to load the IOS from flash to RAM.
Ø This value specifies the router to bypass the startup configuration.
Ø This mode is used to password breakup while saving the configuration.
Ø This mode is used to break the password.
Ø When we start the router in this mode it bypass the startup configuration and then it will ask you
o Would you like to enter into initial configuration dialog? yes/no. n
o After pressing N you will enter into the CLI (Command Line Interface)
Ø Now you are able to configure the new value to your router.
Password recovery
1. Power on the router and press CTRL + BREAK key combination till the router will go into the rommon mode.
2. Change the configuration register value from 0x2102 to 0x2142
a. In case of 2600, 3600, 1700 command is
i. Confreg 0x2142
b. In case of 2500
i. o/r 0x2142
3. restart the router
a. in case of 2600,3600,1700 command to reset the router is
i. reset
b. in case of 2500 command to reset the router is
i. I (initialize)
4. use the copy start run
a. by using the above command copy start run we try to make the start configuration to running configuration so that other configuration remain same while breaking the password. If we does not use this step even then we are capable to break or change the password but the cannot capable to save the startup configuration.
5. Change all the required password.
6. Change the configuration register value back to 0x2102 from the 0x2142.
a. To do so we use the command as
i. Config-register 0x2102
7. Make all the changes permanently saved using the command
a. Copy run start (or)
b. Write
Routers and its discription
Components of a router
| COMPUTER | ROUTER |
| HARDDISK | FLASH |
| RAM | RAM |
| NVRAM | NVRAM |
| ROM | ROM |
FLASH
It is similar to the hard disk of your computer it is EEPROM.(Electrical Erasable Programmable Read Only Memory)
It contains the copy of IOS (Internetworking Operating System)
RAM
Random Access Memory
It is volatile Memory
In case of any sudden power failure all the changes made but not saved get lost.
It contains the running configuration file.
o Running Configuration
§ It is the configuration that has been changed but not saved.
NVRAM
Configuration file is always in NVRAM.
In case of which all changes made and saved will not get lost.
It contains the startup configuration file.
o Startup configuration
§ It is configuration that has been changed as well as saved.
ROM
POST (Power On Self Test). it is used for hardware testing.
BOOT STRAP it’s specify the router from where to load the operating system in the router.
MINI IOS
o It is the mini IOS.
o Mini IOS is the minimum set of driver that is required to boot the router.
Router Booting Sequence
1. POST
2. BOOT STRAP
a. Its specify the router from where to load the IOS.
3. By default the router will load the IOS from flash to RAM.
4. Then the router will look for the saved configuration as start up configuration in NVRAM if it gets this configuration then it will load with that configuration else it will try to go into the setup mode.
a. Would you like to enter into initial configuration Y/N.?
DYNAMIC SYSTEM CONFIGURATIONP
There are two main part of the router
LINES
INTERFACES
INTERFACES
Interfaces are used to connect the router with the LAN or WAN.
Over interface we specify the IP addresses
Type of the interfaces
Ethernet port (used to connect the router with a computer)
Serial port (used to connect the router with other router)
BRI (Basic Rate Interface Port) used for WAN connectivity.
LINES
Lines are used to get the access of a router in order to configure the router.
Over line we specify the login and password. Always firstly we specify the
Password and then we enter the login. Login command activates the line only.
Type of the lines
Console line
Vty line (virtual type)
Auxiliary
PORTS
Ethernet ports
it is an interface that is used to make your router a member of LAN. It is used for LAN connectivity.
Two types of Ethernet ports:
1. RJ 45 female port
2. AUI (Attachment Unit Interface) 15 pin model. In case of AUI Ethernet transceiver will be used. AUI is always simple Ethernet port. i.e. 10 Mbps.
Three categories of the Ethernet port e0, e1, and e0/0
1. Simple Ethernet port 10 Mbps
2. Fast Ethernet port 100 Mbps
3. Gigabit Ethernet port 1000 Mbps
Notes
The router Ethernet port address is the default gateway for all the systems that are member of that LAN.
Console port:
· It is line that is used to get the access of a router in order to configuration it locally.
· Console wire or roll over wire is used for this purpose.
· One end of this console cable is male RJ-45 and other end is com(female) or serial of (9 pin connector)
· It is RJ-45 female ports.
BRI port
· Basic Rate Interface
· It is port where we connect our dedicated ISDN line to our routers.
· It is a RJ-45 female port.
Telephone line ISDN(Integrated Service Digital Network)
It is an analog line It is a digital line
It provides only audio support It provides both audio , video and data
It provides to the max of 56 kbps. It has two B and one D channel. Each B channel is of 64 kbps and
D is of 16 kbps. i.e. total 144 kbps.
Auxiliary port:
· It is a line through which we can get access of router in order to configure it and that is also remotely.
· It is port where we connect our dedicated telephone to our router.
VTY port
· Virtual type
· It is a logical part that does not exist physically.
· It is used to activate telnet service over the router for that purpose we have to set login and password over the vty line.
· Line vty 0 4
· Password
· Login
Serial port
· It is the port where we connect either two routers directly or remotely.
· It is used for WAN connectivity.
· It uses v.35 cable.
· Locally when two router are directly connected using a serial cable.
· Two type of serial port
o 60 pin modular port (DB 60)
o Smart serial
· DB 60
o It is a 60 pin modular port it is always IT( 1 T mean one terminal)
· Smart serial
o Latest and compact
o It can be 1T as well as 2T.
o Two categories of serial interface card.
§ WIC 1T WAN interface Card 1 terminal.
· Only DB60 and smart serial
§ WIC 2T : WAN Interface Card 2 terminal ( means two port on a single interface like USB interface)
· Only smart serial.
Serial cable types
End to end DT/DC cable – 60 pin or smart serial.
One end of the serial cable is DTE (Data Terminating Equipment)
Other end of the serial cable is DCE (Data Circuit terminating Equipment)
DCE is always females. We have to set the clock rate on the 64000.
Different modes of operation
1. User Execution Mode
a. VTY
b. CONSOLE
c. AUXILIARY
By using enable command we can enter in the privilege mode.
2. Privileged mode
a. We can copy or save the configuration in this mode
b. All the command of show is executed in this mode.
3. global configuration mode
a. We can change the configuration in this mode.
User execution mode
It is very limited type of mode, in it neither we can see or nor we can change the router configuration.
Command used in this mode are
a. Ping
b. telnet
c. traceroute
There are two type of the password.
a. Simple enable password
· Plain text password
· Priority low
· To set password command is
1. enable password (password)
note :à this simple password can be seen by show running-config command. Because it is not encrypted.
b. Enable secret password
· Encrypted form
· High priority
· To set secret password command is
1. enable secret (password)
note :-- this password never be seen by the show running-config command. Because it is encrypted.
c. Both passwords never are same.
Privileged mode
It is a mode where we can see or save the router configuration. But we cannot change the router’s configuration.
Commands used in this mode are
Show commands are used to see the configuration.
Copy commands are used to save the router configuration.
Debug commands are used to see the router backend processing to the front end.
Global configuration mode
We can enter in this mode by using the command config terminal or configure
It is the mode where we can change the router’s configuration.
The commands used at this mode are
We can change or set the hostname of the router.
We can change or set the enable secret password
We can set the banners.
Line configuration mode
It is a mode where we can change the configuration relating to any specific line.
Commands used at this mode are
Login
Password
Interface configuration mode
It is a mode where we can change the configuration related to any interface
Commands used at these modes are
We can set the clock rate
We can change or set the IP address.
We can change the status of a specific interface
Classless Inter-Domain Routing (CIDR) Overview
CIDR is a new addressing scheme for the Internet which allows for more efficient allocation of IP addresses than the old Class A, B, and C address scheme.
Why Do We Need CIDR?
With a new network being connected to the Internet every 30 minutes the Internet was faced with two critical problems:
· Running out of IP addresses
· Running out of capacity in the global routing tables
Running Out of IP Addresses
There is a maximum number of networks and hosts that can be assigned unique addresses using the Internet's 32-bit long addresses. Traditionally, the Internet assigned "classes" of addresses: Class A, Class B and Class C were the most common. Each address had two parts: one part to identify a unique network and the second part to identify a unique host in that network. Another way the old Class A, B, and C addresses were identified was by looking at the first 8 bits of the address and converting it to its decimal equivalent.
Address Class # Network Bits # Hosts Bits Decimal Address Range
Class A 8 bits 24 bits 1-126
Class B 16 bits 16 bits 128-191
Class C 24 bits 8 bits 192-223
Using the old Class A, B, and C addressing scheme the Internet could support the following:
· 126 Class A networks that could include up to 16,777,214 hosts each
· Plus 65,000 Class B networks that could include up to 65,534 hosts each
· Plus over 2 million Class C networks that could include up to 254 hosts each
(Some addresses are reserved for broadcast messages, etc.). Because Internet addresses were generally only assigned in these three sizes, there was a lot of wasted addresses. For example, if you needed 100 addresses you would be assigned the smallest address (Class C), but that still meant 154 unused addresses. The overall result was that while the Internet was running out of unassigned addresses, only 3% of the assigned addresses were actually being used. CIDR was developed to be a much more efficient method of assigning addresses.
Global Routing Tables At Capacity
A related problem was the sheer size of the Internet global routing tables. As the number of networks on the Internet increased, so did the number of routes. A few years back it was forecasted that the global backbone Internet routers were fast approaching their limit on the number of routes they could support.
Even using the latest router technology, the maximum theoretical routing table size is approximately 60,000 routing table entries. If nothing was done the global routing tables would have reached capacity by mid-1994 and all Internet growth would be halted.
How Were These Problems Solved?
Two solutions were developed and adopted by the global Internet community:
· Restructuring IP address assignments to increase efficiency
· Hierarchical routing aggregation to minimize route table entries
Restructuring IP Address Assignments
Classless Inter-Domain Routing (CIDR) is a replacement for the old process of assigning Class A, B and C addresses with a generalized network "prefix". Instead of being limited to network identifiers (or "prefixes") of 8, 16 or 24 bits, CIDR currently uses prefixes anywhere from 13 to 27 bits. Thus, blocks of addresses can be assigned to networks as small as 32 hosts or to those with over 500,000 hosts. This allows for address assignments that much more closely fit an organization's specific needs.
A CIDR address includes the standard 32-bit IP address and also information on how many bits are used for the network prefix. For example, in the CIDR address 206.13.01.48/25, the "/25" indicates the first 25 bits are used to identify the unique network leaving the remaining bits to identify the specific host.
CIDR Block Prefix # Equivalent Class C # of Host Addresses
/27 1/8th of a Class C 32 hosts
/26 1/4th of a Class C 64 hosts
/25 1/2 of a Class C 128 hosts
/24 1 Class C 256 hosts
/23 2 Class C 512 hosts
/22 4 Class C 1,024 hosts
/21 8 Class C 2,048 hosts
/20 16 Class C 4,096 hosts
/19 32 Class C 8,192 hosts
/18 64 Class C 16,384 hosts
/17 128 Class C 32,768 hosts
/16 256 Class C 65,536 hosts
(= 1 Class B)
/15 512 Class C 131,072 hosts
/14 1,024 Class C 262,144 hosts
/13 2,048 Class C 524,288 hosts
Hierarchical Routing Aggregation To Minimize Routing Table Entries
The CIDR addressing scheme also enables "route aggregation" in which a single high-level route entry can represent many lower-level routes in the global routing tables.
The scheme is similar to the telephone network where the network is setup in a hierarchical structure. A high level, backbone network node only looks at the area code information and then routes the call to the specific backbone node responsible for that area code. The receiving node then looks at the phone number prefix and routes the call to its subtending network node responsible for that prefix and so on. The backbone network nodes only need routing table entries for area codes, each representing huge blocks of individual telephone numbers, not for every unique telephone number.
Currently, big blocks of addresses are assigned to the large Internet Service Providers (ISPs) who then re-allocate portions of their address blocks to their customers. For example, Pacific Bell Internet has been assigned a CIDR address block with a prefix of /15 (equivalent to 512 Class C addresses or 131,072 host addresses) and typically assigns its customers CIDR addresses with prefixes ranging from /27 to /19. These customers, who may be smaller ISPs themselves, in turn re-allocate portions of their address block to their users and/or customers. However, in the global routing tables all these different networks and hosts can be represented by the single Pacific Bell Internet route entry. In this way, the growth in the number of routing table entries at each level in the network hierarchy has been significantly reduced. Currently, the global routing tables have approximately 35,000 entries.
Where To Get Address Assignments
In the past, you would get a Class A, B or C address assignments directly from the appropriate Internet Registry (i.e., the InterNIC). Under this scenario, you "owned" the address and could take it with you even if you changed Internet Service Providers (ISPs). With the introduction of CIDR address assignments and route aggregation, with a few exceptions, the recommended source for address assignments is your ISP. Under this scenario, you are only "renting" the address and if you change ISPs it is strongly recommended that you get a new address from your new ISP and re-number all of your network devices. While this can be a time-consuming task, it is critical for your address to be aggregated into your ISP's larger address block and routed under their network address. There are still significant global routing table issues and the smaller your network is, the greater your risk of being dropped from the global routing tables. In fact, networks smaller than 8,192 devices will very likely be dropped. Neither the InterNIC nor other ISPs have control over an individual ISP's decisions on how to manage their routing tables.
SUBNETTING
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
§ 2m-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.
Thanks,
IP Addressing
IP ADDRESSING
IP ADDRESSING SCHEMA
In a network every computer having a unique address called IP address which is use to communicate the computer with another computer in the network. Every computer must have IP address. So it very important to understand the concept of IP Addressing Scheme.
An IP address is a 4 octet i.e. 8*4 =32 bits address. Each octet is separated by the dot.
Format of IP address is
0-255.0-255.0-255.0-255
An IP address having two parts. Host ID and Network ID.
192.168.0.1
Here 192.168.0. Is the network ID and 1 is the Host ID
Network ID
This part specifies the unique number assigned to your particular network. It it also the part that identifies the class of network assigned.
Host ID
This is the part of the IP address that you assign to each host, and uniquely identifies each host on your network. Note that for each host on your network, the network part of the address will be the same, but the host part must be different.
IP address having classes
Ø Class A address
Ø Class B address
Ø Class C address
Ø Class D address
Ø Class E address
Class A address scheme
In class A first 8 bits are network address while the remaining 24 bits are host address.
Range of class A is from 0.0.0.0. To 127.255.255.255.
Network address 0 is reserved to designate the default route for the packets and the network address 127 is reserve for the diagnostic to check out the local loop address.
This mean that there are 126 networks are available.
e.g. 86.18.2.4 is a IP of class A with network address 86 and host address is 18.2.4
86.0.0.0. is the network address.
86.255.255.255 is the broadcasting address of a network having network address is 86.
Class B Address Scheme
The first 16 bits are the network ID & remaining 16 bits are the host ID.
The range of the class B address scheme is 128.0.0.0.to 191.255.255.255
142.3.92.19 is an IP that belong to the class B address.
142.3 is the network IP and 92.19 is the Host ID
142.3.0.0. Is the network address
142.3.255.255 is the broadcasting address.
Class C Address Scheme
In the class C 24 bits are the network ID bits and 8 bits are the host ID bits.
The range of the class C address is 192.0.0.0. to 223.255.255.255
192.168.0.10 is the IP of class C. here 192.168.0 is the network ID and 10 is the Host ID
192.168.0.0 is the network address
192.168.0.255 is the broadcasting address.
Class D Address Scheme
The address of this class is used for multicasting. This class does not have any netid and hostid
The IP range for D class address is 224.0.0.0 to 239.255.255.255
Class e address scheme
The address of the E class is reserved for the internet society
The range for the E class is 240.0.0.0 to 255.255.255.255
Point to remember
For class A there is only one private network having netid 10.0.0.
For class B there are 16 private network allowed. Netid for these private networks are from
172.16 to 172.31
For class C there are 256 private network allowed. Netid ranges for these networks are
192.168.0. to 192.168.255
How to convert the decimal IP address to Binary Address?
How to convert 192.168.0.10 to binary number
128 64 32 16 8 4 2 1
Firstly we will convert 192 to binary value. Add the value to make 192 and mark them as 1
128+64=192
So for 192 binary value is 11000000
Other bits are mark as 0
Now 168 =128+32+16+2=10110001
For 0=00000000
For 10 = 8+2=00001010
Now 192.168.0.10 is 11000000.10110001.00000000.00001010
Why we not consider 127 in any range of IP address?
We don’t consider 127 in any IP range because it is reserved as the loop back address. To check the system whether it’s ready for networking or not we use it.
The 127.0.0.1 is known as loop back address. It also allows information technology professionals to test IP software without worrying about broken or corrupted drivers or hardware.
Once you are at a command prompt, enter the following:
Ping 127.0.0.1
If the command is successful, the Ping utility will return results similar to the following. The exact information returned will vary depending on your operating system:
This indicates that the network card and drivers are functioning properly. If the Ping utility is not able to get a return on the network card, this may indicate either a driver problem, or a physical problem with the card.
Private addresses in each class networks
v in class A the private address are
o 10.0.0.0. to 10.255.255.255
v In class B the private address are
o 172.16.0.0. to 172.31.0.0. (16 to 31 networks )
v In class C the private address are
o 192.168.0.0 to 192.168.255.0 (256 networks)
MAC address
Ø MAC address stand for the Media Access Control.
Ø Its 48 bits address
Ø It’s a hexadecimal address
Ø Its known as the hardware or physical address
Ø ARP (Address Resolution Protocol) is used to convert the IP address to MAC address.
POINT TO REMEMBER
Ø When all the host ID portion bits of an IP address are 0, it is a network address.
Ø When all the host ID portion bits of an IP address are 1, then it is a broadcast address.
o 10.255.255.255 ( 10.11111111.11111111.11111111)
Ø When all the net ID portion bits of an IP address are 0, then it is a host address.
o 10.0.0.1 IP address
o 0.0.0.1 host address
Ø When all the net ID bits are 1 it’s represent all the networks.
o 255.0.0.0
Ø When all the net ID bits and host ID bits are 1, its represents global broadcast. Means all networks all hosts.
Ø When all the net ID and host ID bits are 0 , then it is used for default routing
o 0.0.0.0.
Ø 127.0.0.1
o It is loop back address used for self testing. If ping to this address is successful its means the TCP/IP protocol stack is ok. If there is no reply the TCP/IP suite is corrupt it means you have to reinstall the O.S. it does not depends upon the presence of the LAN cards. i.e. if there is no any LAN card present in the computer even then it will reply because it only check the software for the networking ( its means that TCP/ IP suite)
Ø Valid hosts
o Class A 255.0.0.0 224-2
o Class B 255.255.0.0 216-2
o Class C 255.255.255.0 28 -2
Thanks,
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