How many links exchange are recomended by google?

I agree with you, one way link (not exchange) is better to increase SERP, then there are many link brokers available to buy and sell the links..

 

I dont think that is correct - the google webmaster guidelines uses the word "excessive" when discussing link exchanges, as well as some other topics to consider. The problem is, there is no definition of what "excessive" is.

Exchanging links is what you might call a "Link Scheme" - http://www.google.com/support/webmasters/bin/answer.py?hl=en&answer=66356

A few reciprocal links are ok, but do not go overboard on it. Since there is no clear definition of what "excessive" is, there is no way to know how many is too many.

Personally, I try to stay away from trading links.

If you do exchange links, make sure the other site is on the same topic as your site, and add the nofollow tag to prevent the passing of pagerank.

 

there are no such numbers for link exchange but your web page should not contain more then 100 links.