Prefix Announcement Protocol

The prefix announcement protocol allows registering prefixes using a prefix announcement object. It is an alternative to NFD RIB Management protocol's rib/register verb.

Prefix Announcement object

The prefix announcement object is a Data packet that represents an application's intent of registering a prefix toward itself. A Data packet that satisfies the following requirements is a prefix announcement object:

  • Name starts with the announced prefix, followed by a fixed 32=PA keyword name component, followed by a version component and a segment component as defined by the NDN Naming Conventions. In the current revision of this specification, the segment number MUST be zero.
  • ContentType MUST be 5 (prefix announcement).
  • Content contains a sequence of TLV elements, including at least an ExpirationPeriod element. Ordering of these TLV elements is insignificant. Unrecognized non-critical TLV elements are permitted and MUST be ignored.

Validity period of a prefix announcement object is given in ExpirationPeriod and ValidityPeriod elements in its Content.

  • ExpirationPeriod gives the duration for which the prefix announcement remains valid. The duration begins when a node or program receives the prefix announcement. This element is required.
  • ValidityPeriod gives the absolute time range in which the prefix announcement remains valid. It is ignored if the receiving node does not have a UnixTime clock. This element is optional.
  • When both ExpirationPeriod and ValidityPeriod are present, the most restrictive constraint applies.

The trust model of a prefix announcement is to be defined by the application.


  Name /net/example/32=PA/%FD%01/%00%00
    ContentType 5 (prefix announcement)
    ExpirationPeriod 3600000
      NotBefore 20181030T000000
      NotAfter  20181124T235959

This prefix announcement object announces the prefix /net/example. It is valid for one hour from its receipt, between the dates 2018-10-30 and 2018-11-24 (included).

Command Verb: 'announce'

This command announces a prefix using a prefix announcement object. NFD-RIB accepts this command as a signed Interest with the following name:


The Interest's ApplicationParameters element carries the prefix announcement object.
NFD-RIB converts this command into an equivalent rib/register command. The route's origin is set to "prefix announcement" (=129).

The response is the same as the rib/register command.

Note: There is no 'unannounce' command. Instead, use rib/unregister command.


  Name /localhop/nfd/rib/announce/params-sha256=607a2bc7653eea18b47e92b84edc58bab5aaa321d4efb39ceeccc6cafbcbb3d1

Assuming the enclosed PrefixAnnouncement is the one shown in the previous example, NFD-RIB should interpret this command same as rib/register command with the following ControlParameters:

  • Name: /net/example
  • Origin: 129
  • ExpirationPeriod: 3600000; optionally, constrained by the ValidityPeriod of the PrefixAnnouncement

Updated by Davide Pesavento over 1 year ago · 9 revisions