Avoid redundant port counter collection from virtualized instances, such as Cisco VRF

[lunkwill42]

In cases where virtual router instances can be established within a physical router, all the virtual routers will typically be added to NAV (as is the case of Cisco VRF). Depending on the number of virtual instances, this may cause massive overload on the physical "master" router, as NAV will attempt to collect traffic counters from all its interfaces once for each virtual instance in addition to the master instance.

NAV needs a way to mark IP Devices as being virtual instances of a specific "master" IP device, so that it can avoid the redundant collection from multiple devices that are essentially the same.

The simplest way to achieve this is to not collect port stats for virtualized instances, but instead duplicate the data collected from the master for each virtual instance.

There may also be some benefit to avoid redundant linkstate detection on the virtual instances.

The University of Basel, Switzerland is sponsoring this task.

[lunkwill42]

Tagging @mdiehm for feedback here :)

[lunkwill42]

The basic functionality is mostly complete at https://github.com/lunkwill42/nav/tree/vrf right now, but @jmbredal will be modifying the SeedDB UI so virtual instances can be registered properly by users.