Hey folks, At Comcast we have a need to augment CLIENT_STEERING (also regular STEERING while we're at it) to allow targets to be ordered/sorted based upon the client's proximity to the origin of the target delivery services. I'd like to get your feedback on my proposed design and address any of your concerns.
For HTTP_LIVE targets for instance, we'd like edge caches to ideally retrieve/serve data from an Origin that is close to the client and fall back to Origins that are farther and farther away. This allows for increased redundancy while ordering optimal Origins (Delivery Services) for a client to choose from. For example, I have 3 Origins in different locations: Seattle, Denver, and Boston. I would create an HTTP_LIVE delivery service for each origin and a CLIENT_STEERING delivery service with those delivery services as targets. I would then like to have those targets ordered based upon proximity to the client. So a client in Seattle would get the list [Seattle, Denver, Boston], while a client in Boston would get the list [Boston, Denver, Seattle]. To make things more complicated, I want to add a redundant origin in each location and split traffic between them (like STEERING_WEIGHT today) while taking into account the geo-ordering. I also want to be able to force an ordering (like STEERING_ORDER today) among co-located targets. In order to accomplish this I propose to: 1. add two new steering types: GEO_ORDER and GEO_WEIGHT (by adding a target of type GEO_*, a steering DS would then enable geo-ordering) 2. associate a Delivery Service Origin with a latitude/longitude, thereby associating a lat/long to a GEO_* target Item 1 is pretty straightforward and will also play nicely with the current steering types (STEERING_ORDER and STEERING_WEIGHT). I've completed a POC within Traffic Router that basically provides the following ordering when mixing all 4 types in a single steering delivery service: - Negative STEERING_ORDER targets - GEO_WEIGHT and GEO_ORDER targets, grouped by proximity to the client, ordered by geo-order and the consistent-hashing from the weightings - STEERING_WEIGHT targets (consistent-hashed) - Positive STEERING_ORDER targets Item 2 is not as straightforward because the simple thing would be to just add an Origin Lat/Long field to the Delivery Service and call it a day. However I don't think we should do that, and I'll dive more into that in a separate thread (coming soon). Does anyone have questions/concerns about adding these new GEO_ORDER and GEO_STEERING target types and geo-sorting them based upon proximity to the client? Are you okay with the proposed ordering when all the steering types are mixed together? - Rawlin