Giving you a simple example. If you want to be a leader in your area then what would be your process? First of all you will say all person one by one to let you know and to give you vote. If you will talk with single family does not matter how many members there, you can not win from your area.
This way is working also in SEO if you will make links from single IP then you can get about nothing but if you will make links for your website from different IPs then you can be leader of online market.
Google denies that they discriminate against links that came from identical IP address or C category of addresses, thus for Google the IP address is thought-about neutral to the load of inbound links. However, Bing and Yahoo! might discard links from a similar IPs or IP classes, therefore it's invariably better to induce links from totally different IPs. This is what I have learned from an SEO Specialist who helps in the ranking of most outbound telemarketing companies in our locale.
If the backlinks pointing to your website comes from different IP, search engines will consider them as natural backlinks ans will thus give you higher points. Hundreds of links coming from the same IP address means that there's an obvious SEO activity and search engines will devalue the links.
If search engines see that you're getting traffic from multiple IP's, then they'll consider it as natural visits and you will get additional points for it. I know about this as I am working on publishing a book about search engine rankings.