Summary

  • A new individual GROW Internet-Draft would register a BGP path-attribute combination once under a local Attribute Set ID, then send separate prefix-count updates. It requests two new BMP message types; IANA's registry has assigned neither.
  • The router could report counts as events or at a configured interval. In periodic mode, the count reaching zero for any registered set must trigger an immediate ZERO_REF message, ahead of the next scheduled report.

The clock can wait. The empty drawer cannot.

BMP today lets a monitoring station receive BGP route updates from a router. A route-monitoring message carries the route's path attributes along with its network reachability information. Where many prefixes share the same attributes, the router repeats the same descriptive bundle over and over. The 28 October proposal tries to remove that postage without pretending the collector can abandon state.

First comes a declaration. The router assigns a nonzero 32-bit Attribute Set ID, or AS-ID, to a unique ordered combination of BGP attributes and registers the combination with the collector. This AS-ID is a local handle for the attribute set, not an autonomous-system number. A later count update points to the registered handle and says how many prefixes use it. The draft defines absolute counts, additions, subtractions and an explicit zero-reference operation. An unregister message can make the collector discard an obsolete set. These are two proposed message types, still marked TBD1 and TBD2, rather than working IANA allocations.

The operator's choice is where the story turns. The draft says an implementation should offer event-driven count reporting or periodic reporting. Event mode speaks when a route joins or leaves a set. Periodic mode suppresses real-time per-route updates and sends an absolute count at a configured interval; the draft's 30 seconds is an example, not a standard timer. That reduces repetitive traffic but changes the collector's view between reports. A current total is not a replay of every prefix change that produced it.

Then comes the exception. If the count for any AS-ID falls to zero before the next poll, the router must send ZERO_REF at once. The last departure gets an express lane because a quiet interval otherwise hides the disappearance of an entire attribute set. After a broken BMP session reconnects, the router must reannounce all active sets and should follow with initial absolute counts. A collector holding an old handle without the new declaration would be reading a number without its legend.

The Datatracker records this as revision 00 of an individual draft, not a GROW working-group standard. The text gives no measured bandwidth saving, implementation trace or bound on real detection latency. Those are the specific results that would turn a neat wire format into an operating decision. For now it has made the trade explicit: save the repeated paragraphs, set your reporting clock, and let zero interrupt the meeting.

Sources: proposed BMP extension; IETF status; RFC 7854; IANA BMP registry.