TCP/IP Illustrated Vol.1, which edition to read?

As the title says, I want to buy the book but there are two editions of it. One is from 1994, and the newer one from 2011.

Also, the first edition if I'm correct is around ~600pages, and the second ~1000. Why there is so much of page difference or I'm seeing something different?

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TCP/IP Illustrated, Vol. 1: The Protocols (Addison-Wesley Professional Computing Series) 1st Edition

• Hardcover: 576 pages
• Publisher: Addison-Wesley Professional; 1 edition (January 10, 1994)

TCP/IP Illustrated, Volume 1: The Protocols (2nd Edition) (Addison-Wesley Professional Computing Series) 2nd Edition

• Hardcover: 1056 pages
• Publisher: Addison-Wesley Professional; 2 edition (November 25, 2011)

Plain and simply which one should I read?