My peering request was turned down. Why?
It's likely that you may be new at this and mailed the wrong address, or you just don't meet the target peers interconnect policies. Many policies are at http://www.sample.com/peering (Note, that address is not a requirement so please don't flame anyone if it's not there). Some exchange points list their member policies, but the most thorough compilation is available at PeeringDB.
How do I find the correct peering contact?
First try PeeringDB, the de-facto standard database of self-maintained peering arrangements by network, facility, and location. You can also try contacting "firstname.lastname@example.org" and ask for the peering policies, as well as trying http://www.example.com/peering which sometimes works as well. As a last resort, try the NOC database at puck.nether.net and pick up the phone.
What are the basic components to Peering?
Peering is is the interconnection of two networks for economic or other intrinsic value. It is no more complicated or no simpler. Anyone can peer if they want to, but defining the actual benefit is harder. Peering takes time, effort, and actually does cost real money in terms of hardware, facility costs, and time. Defining the value of agreeing "why" peer is the difficult part.
Settlement-based Interconnections is when a fee is paid for access to some part of the global Internet. This may be a flat rate, burstable, or arranged as some sort of ratio-based billing scheme. At the end of the day, money changes hands and one party is the other's customer. The relationship could change month over month, depending upon which direction had out of balance ratio related to the agreement and in which direction.
Transit is paying full access to gain access to the Internet. These are usually in the form of minimim commitments and can run from $15 per mbps to as high as $150, depending upon your savvy in negotiating, how much bandwidth you are buying, and from whom.
Settlement-free Interconnections (aka Peering)
Settlement-free Interconnections (Peering) are where two networks interconnect and exchange traffic with no money changing hands.
Internet Exchange Points (IXPs)
Most exchange point's public fabric is a shared infrastructure managed by a third party. These generally represent a measure of shared resource utilization. For some, people that are pushing a lot of traffic, they represent a relative return on investment. Public fabrics have changed slowly over the years. There are no performance guarantees hence "public". Statistics exemplify the realities of a shared, and managed, infrastructure. The names of the problems have changed, but the faces remain the same. Evaluate reliability and ROI carefully before inserting the needle.
Private Network Interconnects (PNIs)
Private Network Interconnections are direct cross-connects (generally point-to-point) between two networks to dedicate resources. Depending on the respective network architectures, this could be just a dedicated cross-connect, a dedicated card, or router.