PrefixAnnouncement » History » Revision 6
Revision 5 (Junxiao Shi, 08/23/2018 05:54 AM) → Revision 6/10 (Ernest McCracken, 12/20/2018 08:31 AM)
# Prefix Announcement Protocol The **prefix announcement protocol** allows registering prefixes using a *prefix announcement object*. It is an alternative to NFD [[RibMgmt|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 NDN Naming Conventions](https://named-data.net/publications/techreports/ndn-tr-22-ndn-memo-naming-conventions/). Conventions. In this specification revision, segment number is always zero. * ContentType is 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 will 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 restricted constraint applies. Trust model of 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 since receipt, within the date range 30OCT2018 and 24NOV2018. ## Command Verbs ### 'announce' This command announces a prefix using a prefix announcement object. NFD-RIB accepts this command as a [[ndn-cxx:CommandInterest|Command Interest]] with the following syntax: ``` /localhost/nfd/rib/announce/<params-sha256>/<command-interest-components> /localhop/nfd/rib/announce/<params-sha256>/<command-interest-components> ``` The Interest's Parameters element carries the prefix announcement object. NFD-RIB converts this command into an equivalent `rib/register` command. Route *origin* is set to "prefix announcement" (number 129). Response is the same as `rib/register` command. ### 'unannounce' There is no 'unannounce' command. Instead, use `rib/unregister` command.