What does the PIM Bootstrap (BSR) protocol use to elect a BSR router?

The Bootstrap Router (BSR) protocol in PIM (Protocol Independent Multicast) utilizes router priority to elect a BSR router. The primary role of the BSR is to facilitate the distribution of multicast group membership information within a PIM domain. The election process helps to establish a single, authoritative BSR that can manage and distribute this routing information efficiently.

Router priority is a configurable value on the routers, with higher values indicating a higher priority for being elected as the BSR. During the election process, routers send out BSR candidate messages that advertise their priority. The router with the highest priority value becomes the BSR. This selection method ensures that the BSR is chosen based on a predetermined, efficient criterium, providing stability and predictability in multicast routing.

Other potential election criteria like bandwidth, router model, or location do not factor into the BSR election process. Router bandwidth is more relevant to routing protocol operations but does not play a role in BSR election priorities. Similarly, while different router models may have varying capabilities, the election is not determined by the model itself. Lastly, the physical location of the router does not influence its ability to become the BSR; the critical factor is the router priority as defined in the configuration.