This is real simple … but people sometimes gets confused and say
“how to do this ? is this the right way? ” and so on…
lets include a small post for wildcard mask too…
let us you wanted to calculate the wildcard mask for 255.255.224.0
can you tell me in one second?? hehehe
simple
255-255 = 0
255-255 = 0
255-224 = 31
255 – 0 = 255
so wildcard mask would be
0.0.31.255..
|
The credit for this courses goes to MR.spacyfreak
He is currently pursing his ccsa and done with following CCNA / MCSE / MCSA / MCP / LPI You think Subnetting is a beast? You are wrong! Here the step-by-step course. What is a Subnetmask? With Subnetmasks, we can divide an IP-Address in If we for example have the network 192.168.10.0 255.255.255.0 The useable IP Range of this network is 192.168.10.1 – 192.168.10.254 The very last IP of each Subnet is called Broadcast-Address. If we want to divide this network in two parts, With Subnetmask 255.255.255.128 we would 192.168.10.1 – 192.168.10.127 192.168.10.128 – 192.168.10.255 So in this example, BEFORE we had one big Network.
First with Subnetmask 255.255.255.0 we had “Network-IP” which is NOT useable for Host-PCs 192.168.10.1 192.168.10.2 192.168.10.3 192.168.10.4 192.168.10.5 … … … 192.168.10.253 192.168.10.254 192.168.10.255 >>>This is the Broadcast-IP, which is NOT useable for Host-PCs Now with Subnetmask 255.255.255.128 we have First Subnet: 192.168.10.0 >>> This is the “Network-IP” which is NOTuseable for Host-PCs 192.168.10.1 192.168.10.2 192.168.10.3 192.168.10.4 192.168.10.5 … … … 192.168.10.125 192.168.10.126 192.168.10.127 >>>This is the Broadcast-IP, which is NOT useable for Host-PCs Second Subnet: 192.168.10.128 >>> This is the “Network-IP” which isNOT useable for Host-PCs 192.168.10.129 192.168.10.130 192.168.10.131 192.168.10..132 192.168.10.133 … … … 192.168.10.253 192.168.10.254 192.168.10.255 >>>This is the Broadcast-IP, which is NOT useable for Host-PCs The Subnetmask defines how big the subnet is. A Subnetmask of 255.255.255.0 means in binary 11111111.11111111.11111111.00000000 So, what do we see? 4 Blocks, divided with a “.”. Each of these blocks is also To be able to do subnet-calculation, we first must Lets take the first block. The first “1″ stands for a 128. The second “1″ stands for a 64. The third “1″ stands for a 32. The fourth “1″ stands for a 16. The fifth “1″ stands for a 8. And so on. That means: 11111111=255 11110000=240 11100000=224 If we see something like “/24″, that means that Examples: /16 = 255.255.0.0 = 11111111.11111111.00000000.00000000 /20 = 255.255.240.0 = 11111111.11111111.11110000 If we would take a subnetmask of 255.255.255.255 that would 128+64+32+16+8+4+2+1.128+64+32+16+8+4+2+1. and in binary it would be 11111111.11111111.11111111.11111111 Calculation of Subnetmask big enough for a If they ask.. “create a subnet with minimum 10 host IPs” than 1. calculate a power of two, that is minimum 10 2^3=8. That is not enough 2. Now put the LAST 4 Bits of your subnetmask to 0. 11111111.11111111.11111111.11110000 That is in decimal 255.255.255.240 With THIS Subnetmask, you have minimum 10 Host-Ips ———————————————————— If they ask Create a subnet with minimum 70 Host-IPs 1. Calculate a Power of 2 that is MINIMUM 70 2^6=64. Not enough. 2. Put the LAST 7 Bits of your Subnetmask to 0. 11111111.11111111.11111111.10000000 That is in decimal 255.255.255.128 You have a Subnetmask, with more than 70 Host-IPs. ————————————————————————- Calculation what is the Broadcast-IP of a Subnet When they ask 1. Step /20 meens 255.255.240.0 2. Step Now analyze the Subnet Oktett to find out the 240 means 11110000 The LAST of the 1s is under decimal 16. Write down the network-jumps 172.16.64.0 – 172.16.79.255 Because the NEXT Subnet in the example is ———————— Other example of Broadcast-IP calculation: If it would be 172.16.64.0 /26 Same procedure /26 means 255.255.255.192 192 is binary 11000000 172.16.64.0 – 172.16.64.63 << ——————————————————————— Calculating first and last possible IP for a Host You have Network 192.168.20.32 /27 1.Step /27 is 255.255.255.224 2.Step 224 means 11100000 The LAST 1 is under the 32. Valid IPs in that subnet: 192.168.20.33 – 192.168.20.62 (192.168.20.63 is NOT useable, this is the very last IP and so the BROADCAST-IP). 192.168.20.64 <<
for Default Gateway, our first Host-PC IP would be The very last Host-PC IP would be ################################################################### Here some examples of real exam questions, and Given that you have a class B IP address network range, Solution: Allways the same game… Like in 5 minute course.. Power of 2 that is minimum 500? Now – put the last 9 Bits of your Subnetmask to “0″ 11111111.11111111.11111110.00000000 That is in decimal ===================================================================== Solution: 172.16.45.14/30 /30 means 11111111.11111111.11111111.11111100 The last of the ones stands under the “4″. As we see, the Ip is in the Range of ================================================= Solution: /28 means 11111111.11111111.11111111.11110000 The last 1 stands under the 16. This is increment 192.168.15.0 – 192.168.15.15 Only A and C are IPs in the right range. ################################################################ ————————————————————————————————————————- Calculation of Wildcard-Masks You have Network 192.168.32.0 /28 1. Step /28 means 255.255.255.240 binary this is 11111111.11111111.11111111.11110000 For wildcard-mask only the ZEROS are interesting. 11110000 Make a addition of all the fields, that are set to zero 128/64/32/16/8/4/2/1 So the wildcard-mask will be access-list will be access-list 1 deny 192.168.32.0 0.0.0.15 now, we have to bind that access-list to a routerinterface. interface e0 ————————————————————————————————————————- PS. Its good to write on a BIG paper the powers of 2 2^2=4 And write on that paper the numbers 128 192 224 240 248 252 254 Cause this are the Numbers, you will allways need Burn them in your mind! Hang the paper in front Isnt live easy?
|
|
| |
|
SIMPLY CHECK OR TICK SPARSEMEM WHICH IS NOT TICK BY DEFAULT IN THE GNS3 SECTION
THE REASON BEHIND THIS IS AS FOLLOWS ….
Memory Usage Labs can consume a large amount of real and virtual memory. The “ghostios” and “sparemem” options were added to address both of these issues, respectively.
The Ghostios option can significantly reduce the amount of real host RAM needed for labs with multiple routers running the same IOS image. With this feature, instead of each virtual router storing an identical copy of IOS in its virtual RAM, the host will allocate one shared region of memory that they will all utilize. So for example, if you are running 10 routers all with the same IOS image, and that image is 60 MB in size you will save 9*60 = 540 MB of real RAM when running your lab. Ghostios is enabled, by default, in GNS3.
The “sparsemem” feature does not conserve real memory, but instead reduces the amount of virtual memory used by your router instances. This can be important, because your OS limits a single process to 2 GB of virtual memory on 32-bit Windows, and 3 GB on 32-bit Linux. Enabling sparsemem only allocates virtual memory on the host that is actually used by the IOS in that router instance, rather than the entire amount of RAM configured. This can allow you to run more instances.
Both features rely on mmap, so this must also be enabled. Select Preferences under the Edit menu within GNS3. Check the appropriate boxes to enable these features.
CREDIT GOES TO MIKE
Credit goes to Mike fuszner @ gns3 for the following suggestions …..
TO our gns3 we can do few more enhancements to make ourself more comfortable … first thing it to ….change the telnet client … you can have either putty or teraterm both are good to have i prefer putty ….
PuTTY: http://www.chiark.greenend.org.uk/~sgtatham/putty/
TeraTerm: http://hp.vector.co.jp/authors/VA002416/teraterm.html
Just download the terminal program you prefer and install it on your computer. Inside GNS3, choose Preferences under the Edit menu. Choose General in the left pane, and the change the Terminal command box to read:
For PuTTY: c:\putty\putty.exe -telnet %h %p
For TeraTerm: c:\ TTERMPRO\ttssh.exe %h %p /W=%d /T=1
so we are done with this ….
If you are using a topology that opens several console windows, it becomes a bit of a challenge switching from one device to another. You may consolidate all of these windows into one application where the windows are located under tabs. There are several ways to do this, but the program I like is called WinTabber. It’s another free download at the following site:
http://www.wintabber.com/
after the download click on wintabber and go to file —> add tab —> add the tabs of your choice they all would be under one roof …
CAN YOU SEE THE MULTIPLE TABS …
regards
RAKESH
The configuration is absolutely simple .. it used to be hard for me as i dint have any guides to follow .. now there are many ways to follow a tutorial and install gns3 with little or no pain …
—————————————————————————————————
so first and foremost step is to download the latest copy of gns3 from their website …
you can do it from here
now after doing it the installation is straight foreward and clicking next will do …
—————————————————————————————————
click on test .. and if any alert comes choose ublock
You need to start the dynampis server and make sure you get a message like this
“DYNAMPIS SERVER STARTED SUCCESSFULLY”
————————————————————————————————-
STEP 2 : loading ios …
you need to have your own cisco ios …..
click on number two to get the below screen …
or alternatively open gns3 —> preferences —> ios images
*MAIL ME IF YOU HAVE ANY ISSUES WITH STEP 2
————————————————————————————————
rightclick on router and click on start …..
—————————————————————————————————
you are done … now the most important step is to configure idlepc value
before doing or calculating idlepc value
hit ctrl + alt + del and see the cpu utilisation .. and to no surprise you will see it be 100%
now this could be trouble some , in order to bring down the cpu usage you need to calculate idlepc value ..
rightclick on router and hit on idlepc … you will presented with the following image … select the idlepc value with asteric * mark
after idlepc value the cpu utilisation should be reduced and you should see a low cpu utilisation like this
you should be seeing the following image …
After Applying the idlepc value… thats it … its time for console and configuration of you router which behave as if like a original cisco one … the following are the shots of the images from my console …
-
————————————————————————————————-
after you are done with the configuration part ..
goto file —-> new(project) #here dont go for file go for project# —- select yes …
and you are done bingo
————————————————————————————————
CONGRATULATIONS YOU HAVE YOUR CISCO ROUTER RUNNING ….
any issues feel free to comment …
regards
RAKESH
hai as all of you know , accessing a cisco router or buying it is very hard and only few people can afford that … so people start practicing on bad simulators … and they dont get the concept .. at ccna and ccnp level it is important to learn concept with original ios as we will be aiming for a ccie …
the reason behind this is simple .. simulators are programmed by a programmer who inputs maximum number of commands he knows .. he cannot put a cisco ios in the simulator… so most of the commands wont work for real life on a sim ..
in order to overcome this people started using gns3 … graphical network simulator … you still thinking by the name as it is called a simulator .. yes its a stimulator but uses the original cisco ios and this is what makes it original .. and it will behave as a router when installed on a computer …
it can be used to practice all the ios commands and codes unlike an dupe sim…
so here we go …
The following would be my study plan for the rest of bsci course … i will be posting all the info regarding that .. so be in touch and post any problems you are facing regarding any thing i would be more than happy to help you ..
################################################################################
###################
I will go with module wise first i will start of with GNS3 and after that ccnp bsci and ccie bsci
GNS3
gns3.net the tutorial pdf
hacki website (setting up an access server)
cbt nuggest ccie (tips and tricks for router aliases)
few tricks from scott morris for ccie lab…(creating aliases and using shortcuts and reloading routers time to time etc for lab every day )
################################################################################
###################
next is with the BSCI series
CISCO STUDENT STUDY GUIDE
CBTT CCNP
CISCO CCIE STUDENT GUIDE R AND S
CISCO CCIE IPEXPT BSCI CONCEPTS
CISCO CCIE CBT R AND S BSCI CONCEPTS
CBTT LABS
CCIE WRITTEN LABS
CCIE IPEXPT LABS
CISCO EXAM GUIDE
TRAIN SIG
HACKI SITE
################################################################################
###################
good luck
regards
RAKESH
