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PrefixAnnouncement » History » Revision 9

Revision 8 (Junxiao Shi, 02/07/2020 06:06 AM) → Revision 9/10 (Davide Pesavento, 02/10/2020 08:21 PM)

 
 # 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 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 since receipt, between within the dates date range 2018-10-30 and 2018-11-24 (included). 2018-11-24. 

 ## 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 Route *origin* is set to "prefix announcement" (=129). 

 The response (number 129). 
 Response is the same as the `rib/register` command. 

 Note: 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 the ValidityPeriod of the PrefixAnnouncement