Issue Template

Title: * On demand S/RDS

Description:

Issue for tracking on-demand SRDS implementation.
to make better use of resources (RAM, CPU), make RDS on-demand from SRDS.An example use scenario is that in a MT proxy, many long-tail route tables arent that active, in stead of fetching and storing these route tables via SRDS, we can put them into a "secondary tier", and only fetch the route table when there are such requests hitting the proxy.

[optional Relevant Links:]

issue for on-demand routes #2500