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.

The validity period of a prefix announcement object is given in the 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.

Example¶

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

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).

RIB 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:

/localhost/nfd/rib/announce/<params-sha256>
/localhop/nfd/rib/announce/<params-sha256>

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. Use the rib/unregister command instead.

Example¶

Interest
  Name /localhop/nfd/rib/announce/params-sha256=607a2bc7653eea18b47e92b84edc58bab5aaa321d4efb39ceeccc6cafbcbb3d1
  MustBeFresh
  ApplicationParameters
    PrefixAnnouncement
  InterestSignatureInfo
  InterestSignatureValue 

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