As stated above, these Peering Inclinations are are articulated in roughly three classes of Peering Policy.

Definition: A Peering Policy is an articulation of the Peering Inclination; it documents and defines the prerequisites to peering.  Sometimes these are posted publicly on their websites, and sometimes they are viewable only under a Non-Disclosure agreement. 

Open Peering Policies. We see in the field that most Tier2 ISPs and Content Providers (that peer) have an Open Peering Inclination. They may or may not have an articulated Peering Policy. Yahoo! for example has a one word Peering Policy: “Yes!” . Here are a few examples of Open Peering Policies:

init7.net - http://www.init7.net/peering.php

CAIW Netwerken - http://www.as15435.net/pp/

Steadfast Networks - http://steadfast.net/corporate/peering.php

WISCNet - http://www.eng.wiscnet.net/peering/

NetAccess : http://www.nac.net/eng/peering.asp

Selective Peering Policies. Some Tier 2 ISPs, particularly those deployed across many markets and Interconnection Regions, have a Selective Peering Inclination intended to manage traffic effectively and perhaps to ensure that they are getting equal value from a peering relationship. They may design a peering policy to make sure that the peer adheres to engineering criteria (adequate backbone scale, multiple interconnection regions, etc.) or operations criteria (a 24/7 NOC and updated contact and pager information, etc.). There are a wide range of Selective Peering Policies reflecting a Selective Peering Inclination. Here are a few examples:

peer1 - http://www.peer1.com/infrastructure/peering.php

Bouygues Telecom - http://peering.as5410.net/

BT - http://www.bt.net/info/peering.shtml

EasyNet - http://www.noc.easynet.net/network/public/peering.php

AboveNet - http://www.abovenet.com/peering/

Comcast - http://www.comcast.com/peering/

Here is an old Teleglobe 2002 Peering Policy that documents a selective policy.

Restrictive Peering Policies. Tier 1 ISPs generally have a Restrictive Peering Inclination articulated in their Restrictive Peering Policies. Since they are only required to peer to ensure connectivity for their customers, and they forego revenue by peering, there is not much incentive to accept additional peers. The Sprint Peering Policy is not available on the web but was cited to include an extraordinarily large capacity to Europe and an only slightly less capacity to Asia. Since very few would meet these requirements, they are generally seen as restrictive. Here are some examples of Restrictive Peering Policies:

Qwest - http://www.qwest.com/legal/peering_na.html

AT&T - http://www.corp.att.com/peering/

Verizon - http://www.verizonbusiness.com/terms/peering/

Telstra -

Sprint -

Global Crossing -

Level 3 -

Tata -

old UUNET Global Site WorldCom Policy for Settlement-Free Interconnection with Internet Networks

There are no well-defined delineations between these policies. One might view a Selective Peer as actually Open when the requirements are trivial to meet, and another might see the requirement to fix peering when it breaks as enough of a requirement to classify the peer as Selective. One observer’s Selective peering prerequisites might be seen as so onerous to another as to make the other see the potential peer as Restrictive.

Our research has identified four generalized Peering inclinations.

Definition: A Peering Inclination is a predisposition towards or against peering as demonstrated by Peering behavior in a Peering Ecosystem.

There are four general classes of Peering Inclinations seen in the Peering Ecosystem:

Open means that the entity will generally agree to peer with anyone in any single location with no prerequisites.  An Open peer might be seen actively engaging in peering discussions at Peering Forums.

Selective means that the entity will generally peer but there are some prerequisites (such as meeting in multiple Interconnect Regions, with a minimum traffic volume, not to exceed a certain In/Out traffic ratio, etc). The Peering Policy documents these prerequisites, which, once met, generally lead to peering. A Selective peer may participate in Peering Forums and Internet Exchange Point meetings, but knows that there are  limited set of potential peers, so are not quite as enthusiastically pursuing peering at these fora.

Restrictive means that the entity is generally not open to new peering. The Peering Policy documents extremely difficult to meet peering prerequisites, with the unstated purpose of denying peering. Only rarely will these folks show up to Peering Fora, and they will certainly not seek peering within their own Internet Region. They simply can reach all routes within their Internet Region already solely using their existing peering relationships. As Waqar Khan (Qwest) put it “We have all the peering we need.” And he is correct. James Spenceley calls Telstra’s peering inclination “Make It Long and Difficult (MILD)”, changing the policy as potential peers get close to meeting it. This type of pattern of behavior behavior is consistent for Tier 1 ISPs across most of the Internet Regions studied.  As John Milburn (former Dacom) put it “The desire to protect one’s home market far exceeds any value that peering could provide.”

No Peering means that there is no intention for the entity to ever peer. Content Providers who prefer Internet Service solely through transit agreements are the largest set of players within this category.

Note that these inclination categories fall along a continuum.

There is debate about what “Open” truly means. For example - if Yahoo! (if you have a pulse, they will peer with you) requires a peer to repair peering issues on a timely basis, does that project Yahoo! into the Selective classification?  Some Restrictive peers believe they are more accurately classified as Selective, since they accepted new peers recently, demonstrating their willingness to peer.

So why categorize peering inclinations like this?  These categories are practical shorthands for peering conversations. If a peering prospects says they are open, you can breath a sigh of relief, the peering conversation is likely to yield peering.  If a peering prospect categorizes themselves as “Selective”, the next questions are “What are you peering requirements?” and the discussion flows to whether or not you meet or will meet their requirements.  If a prospect says they are “Restrictive”, then you can make a snide comment and spend your time looking for interested peering prospects.

Next Page: How to Peer

Vijay Gill (AOL) pointed out that there may be a “life cycle” of peering inclinations, where peers migrate from public towards private peering as the scale increases. There is much debate regarding the virtues of de-peering, and of pulling away from public peering.

OPEN

RESTRICTED

SELECTIVE

Peering Inclinations vary by Region. It is also important to note that these peering inclinations are Internet Region specific; that it, a Tier 1 in their home market is likely to have a Restrictive peering inclination and in foreign Internet Region is likely to have an Open or Selective peering inclination.  For example, Singapore Telecom is a Tier 1 ISP in Singapore, and as expected, has a “Restrictive” inclination in Singapore, but an “Open” peering policy in Los Angeles, CA.

Check out the DrPeering examination of Peering Policies article. It is a study of 28 peering policies, includes all the common policy clauses, categorizes them and includes the actual text in each category for your examination.