RPKI is a security framework by which network owners can validate and secure the critical route updates or Border Gateway Protocol (BGP) announcements between public Internet networks. BGP is essentially the central nervous system of the Internet and one of its fundamental building blocks.
The main function of BGP is to facilitate efficient routing between Autonomous Systems (AS), by building and maintaining the Internet routing table.
The Internet routing table is effectively the navigation system of the Internet and without it, traffic would be unable to flow between its constituent networks.
Unfortunately, routing equipment alone cannot distinguish between legitimate and malicious routing announcements, but network operators who implement RPKI validation and filtering can choose to reject announcements from networks not authorised to advertise those resources.
In other words, RPKI is essentially a secure identification system for the BGP route information between autonomous systems.
With route origin validation (ROV), the RPKI system tries to closely mimic what route objects in the IRR intend to do, but then in a more trustworthy manner. It also adds a couple of useful features.
Origin validation is currently the only functionality that is operationally used. The five RIRs provide functionality for it, there is open source software available for creation, publication and use of data, and all major router vendors have implemented ROV in their platforms. Various router software implementations offer support for it, as well.
Using the RPKI system, the legitimate holder of a block of IP addresses can use their resource certificate to make an authoritative, signed statement about which autonomous system is authorised to originate their prefix in BGP. These statements are called Route Origin Authorisations (ROAs).
In addition to the origin AS and the prefix, the ROA contains a maximum length (maxLength) value. This is an attribute that a route object in RPSL doesn’t have. Described in RFC 6482, the maxLength specifies the maximum length of the IP address prefix that the AS is authorised to advertise. This gives the holder of the prefix control over the level of deaggregation an AS is allowed to do.
For example, if a ROA authorises a certain AS to originate 188.8.131.52/24 and the maxLength is set to /25, the AS can originate a single /24 or two adjacent /25 blocks. Any more specific announcement is unauthorised by the ROA. Using this example, the shorthand notation for prefix and maxLength you will often encounter is
GOLINE, AS202032 is matching RPKI validation state and rejects invalids ‘invalid == reject’