difficult sentences

[adel87]

dear sir in these sentences
1)percentage of traffic to cross a network backbone to reach common destinations—quite a
departure from the 80/20 rule.
i don't understand quite a departure
2)One drawback to Layer 2 switching is that it cannot be scaled effectively. Switches must forward
broadcast frames to all ports
3)i don't understand to be scale
Although you can
leverage high-speed LAN technologies to improve any traffic
i don't understand leverage
4)Although campus network design is presented as a three-layer approach (access, distribution, and
core layers), the hierarchy can be collapsed or simplified in certain cases.
i don't understand collasped
thank you for all

[Ann1977]

Hi, Adel ~

1)percentage of traffic to cross a network backbone to reach common destinations—quite a departure from the 80/20 rule.
i don't understand quite a departure

"Quite a departure from" means that it is "quite different from."
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2)One drawback to Layer 2 switching is that it cannot be scaled effectively. Switches must forward
broadcast frames to all ports
i don't understand to be scale

"to be scaled" must be a technical term. I don't know the meaning.
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3) Although you can leverage high-speed LAN technologies to improve any traffic
i don't understand leverage

This is an analogy to the mechanical advantage of the tool called a "lever."
In this use, it refers to the advantage you get from being in a superior position or from having superior power.

Here is a fanciful drawing illustrating the words of the Greek mathematician
Archimedes of Syracuse (c. 287 BC – c. 212 BC) who said,
"Give me a lever long enough and a place to stand, and I will move the world."




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4)Although campus network design is presented as a three-layer approach (access, distribution, and core layers), the hierarchy can be collapsed or simplified in certain cases.
i don't understand collasped

"To collapse" means, in this case, to shape into a more compact form, to sink one part into another to make the whole thing smaller or simpler.

Some chairs are designed to collapse -- to fold up into a smaller size
http://www.cpsc.gov/cpscpub/prerel/prhtml08/08106b.jpg

Here's a collapsible telescope, designed so that the parts can sink into each other
http://www.hiltonphoto.co.uk/images/..._swarcts85.jpg