CSE 316 · Session 11 · try it yourself

One line from the ISP — and the four facts hiding in it

Any address in the block plus the prefix length is enough to recover all four facts. Run the ritual in order: N, the mask, the AND, and plus N minus one.

Any address in the block

Is this address in the same block?

Prefix length /28

STEP 1

N — how many addresses

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STEP 2

The mask

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STEP 3

First address — the network

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STEP 4

Last address

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The street — blocks of this size tile the space, and yours is one of them

Step three, in binary — only the boundary octet fights

Membership — what a router actually computes

bitsarebits.com · CSE 316 — Data Communication & Networking · Forouzan §18.4