A Mesh Federation provides a legal and policy umbrella so that institutions can interact with one another but does not specify technical methods. Each member organization issues digital identities for its people and the federation agreement provides the legal framework for them to use one another’s resources. The federation agreement might specify governance, policy, or roles, but the member institutions are free to implement using whatever technologies they like. This is referred to as a mesh because participating services connect directly with one one another in order to authenticate identities. For contrast, a federation network that provides a central identity clearing house is referred to a Technical federation (discussed below).
Examples: Mesh federations were pioneered by educational institutions. Universities already had a culture of cooperation and realized that the interest of students and research goals of faculty were best served by the free flow of information. NRENS (National Research and Education Networks) around the world include InCommon in the US, SurfnNET in the Netherlands, and JISC/Janet in the UK.
When to use: Large institutions wish to share resources and can agree on roles and governance, but do not need a central point for authenticating identity.
Advantages: Federation participants don’t need to negotiate custom agreements with every other member.
Disadvantages: Because of the need to gather broad adoption, mesh federations may be limited to the most common roles and might not cover complex use cases.
Ability to Scale: Because the mesh federation provides a standard contract, it scales to a large number of members.
The full papers is downloadable [Field-Guide-Internet-TrustID] Here is a link to introduction of the paper and a at the bottom of that post is a link to all the other models with descriptions. Below are links to all the different models.