Diameter End‐to‐End Communication

This chapter looks at the details of communication between two Diameter nodes that are not adjacent. The routing table is a data structure internal to the Diameter node that contains information on how to handle Diameter request messages: either consuming the request message locally or processing the request further before routing it to the appropriate adjacent peer. The Diameter request message routing relies on both the destination realm and the Application‐Id. While reaching the final destination, the destination host, if present, is used to forward the message to the correct peer node. Diameter end‐to‐end communication relies on a number of routing AVPs. Unlike what the category name suggests, these AVPs are not used for the request routing or forwarding, but to record the used route and the state information of the traversed agents. The End‐to‐End Identifier is used for detecting duplicated messages. The chapter discusses the topic of large multi‐realm inter‐connecting Diameter networks.