PrefixAnnouncement » History » Revision 8
Revision 7 (Davide Pesavento, 06/25/2019 09:52 AM) → Revision 8/10 (Junxiao Shi, 02/07/2020 06:06 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 Naming Conventions](https://named-data.net/publications/techreports/ndn-tr-22-ndn-memo-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 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 2018-10-30 30OCT2018 and 2018-11-24. 24NOV2018. ## Command Verb: Verbs ### 'announce' This command announces a prefix using a prefix announcement object. NFD-RIB accepts this command as a *signed Interest* [[ndn-cxx:CommandInterest|Command Interest]] with the following name: syntax: ``` /localhost/nfd/rib/announce/<params-sha256> /localhost/nfd/rib/announce/<params-sha256>/<command-interest-components> /localhop/nfd/rib/announce/<params-sha256> /localhop/nfd/rib/announce/<params-sha256>/<command-interest-components> ``` The Interest's ApplicationParameters 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. Note: ### 'unannounce' There is no 'unannounce' command. Instead, use `rib/unregister` command. ### 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 ValidityPeriod of the PrefixAnnouncement