Hi ALTO working group, After some internal discussions, we are reaching some agreements on the path vector draft. Below are some key design points and your comments and feedback are highly welcomed.
1. A new cost type for path vector We feel more comfortable with the cost type used in -v05, where the mode is "array" and the metric is "ane". It conveys the idea that the results are JSON arrays and the values should be interpreted as identifiers of abstract network elements. 2. A mechanism to query properties of abstract network elements Since we move the property of an abstract network element out of the cost type, a new mechanism is required so that 1) a server can announce what properties can be contained in the response, and 2) a client can specify its desired properties. Unfortunately, this is one point where we don't have consensus. One simple solution is to add a new capability (e.g., "ane-properties") to the IRD entry, and a client should also specify the intended properties in the "ane-properties" field. A second option is to reuse the designs of unified property map. Precisely, a path vector service should announce at least one entity domain "ane" and associated properties, as defined in the unified property map draft. 3. Encoding two messages Each path vector response consists of an (endpoint) cost map and a unified property map. Eventually, we decide to use the multipart/related media type and specify whether it contains a cost map or an endpoint cost map in the "type" parameter in the IRD. This serves two purposes: 1) it guarantees the returned path vector and the properties are consistent, and 2) it only takes one communication cycle and the server doesn't have to keep the state. We are going to present more details about the current design in the draft discussion meeting next week (June 26) and hopefully finalize the design before IETF 105 submission deadline (July 8). You are more than welcome to join the discussion! Many thanks! Best, Kai
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