ISL:
ISL is Cisco Proprietary, not usable in multivendor environments. IT will encapsulate the entire frame and place both header and trailer onto the frame, which will increases the overhead on trunk line. Because ISL does not use the concept of native Vlan (Vlan 1 Default in Cisco switches), every single frame transmitted across the trunk will be encapsulated. ISL adds 26-byte header, which contains Vlan ID and adds 4-byte trailer contains CRC value.
Frames larger then 1518 byte (Max size for Ethernet frame) called GIANTS. ISL encapsulation adds 30 byte to the original frame, which makes them too large for the switch to handle.




Dot 1Q:

Dot 1Q is the IEEE standard suitable for multivendor. Dot1Q does not encapsulate frame, it just adds 4-byte header to the frame and adds nothing to native Vlan frames. Adding only 4-byte to the frame results less overhead then ISL .Maximum frame size of 1522.

If you are a Windows user and Want to switch or just try Linux. But you don’t want to take a risk of dual boot or you don’t have an extra testing computer.

You can run booth of your Operating systems simultaneously. So you can get use to your new OS while using your current OS (Windows). And that by using your Windows as host and your new OS(Linux) as guest .


Things you need :
1- Desktop or Laptop with at lest 1.8 Ghz processor
2- Extra Monitor (to create dual monitor)
3- 3 GB of Ram at lest.
4- 2GB Flash memory
Software you need:
1- Linux ISO image (Ubuntu, fedora,Opensuse) what every you like.
2- eBooster (converts the Flash memory to Ram) and I don’t care how you get it buy it or ……
3- VirtualBox it is free (www.virtualbox.org) download Windows host version.
4- virtual-box-windows-guest-additions-installer Its also free (http://code.google.com/p/virtual-box-windows-guest-additions-installer/)
steps
1-First you set your dual monitor and to do that just connect your Old monitor to your laptop. If you are using windows 7 Right clickScreen Resolution Detect. Set the Multiple displays to (Extend this displays).
2- Install eBooster and after you finsh connect your flash memory and right click ReadyBooster set the amount of space you want to use (prefer 1024).
3- Install VirtualBox.
4- configure your VirtualBox and create new virtual pc (linux).
5- after you finshed installing your new OS (linux) install the virtual-box-windows-guest-addition inside your virtual pc.
6- now you can run your primary OS in one screen and the virtual OS in other.

Enjoy your both Operating systems

fill free to ask any question about any step you don't understand and I will give a detailed instruction.
or email me ali.2011@live.com

CCNA Certification: Trunking Concepts Part II

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CCNA Certification: VLAN Trunking Protocol (VTP) Part I

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