Provider Independent Addresses Aggregation

This document proposes a discussion on whether PI address aggregation is necessary, and if so, what methods can be considered. It also summarizes the current status of PA addresses and PI addresses. More research, reviews, and discussions will be added in the future.

Route aggregation technology was developed as a measure to deal with the routing table explosion in IPv4. Route aggregation is a prerequisite for IPv6.This is called PA (Provider Addresses). Meanwhile, PI (Provider Independent addresses) were considered for multihoming, but they have the characteristic that they cannot be aggregated. It is assumed that most currently in use are PA. Looking back at the spread of IPv4, initially, the equivalent of PI addresses was used. In those days, organizations obtained addresses from a registry, rather than from the provider they were connecting to. It has expanded through a bottom-up process. From the perspective of operators of so-called intranets that have been built on this premise, obtaining addresses from a provider under IPv6 may be a good idea because it simplifies the process, but they may be concerned about being dependent on the provider. Or, if some intranet already has a multihoming configuration, operators may be wondering which PA address to use with IPv6. Looking back at this history, it seems natural to use PI addresses for intranets. However, if PI addresses are increasingly allocated to corporate and campus networks, the problem of routing table explosion will likely become a reality, since they cannot be aggregated. If one of the issues in the deploy of IPv6 to intranets is the difficulty of using PI addresses, this should be resolved. In that case, it would be desirable to obtain a perspective on the aggregation of PI addresses. In other words, author propose a discussion on whether aggregation of PI addresses is necessary, and if so, what methods can be considered.

In this section, the current situation of PA and PI is described.

There are three RFCs for PA. First, "An IPv6 Provider-Based Unicast Address Format" (RFC2073), then "An IPv6 Aggregatable Global Unicast Address Format" (RFC2374), and now "IPv6 Global Unicast Address Format" (RFC3587).

There are no RFCs for PI.

In multihoming, if the connection links are the same ISP, the PA address can be used. In multihoming, if the connection links are different ISPs, the PI address can be used. Note that IPv6 allows multiple IP addresses to be assigned to an interface, so it is also possible to assign provider base addresses from different ISPs. However, the issue is how to handle source address selection.

If PI addresses are assigned by the RIRs, one option would be to aggregate them at the RIR level. However, it seems likely that such aggregation could occur somewhere between the RIR level and the ISP level.

This document makes no request of IANA. Note to RFC Editor: this section may be removed on publication as an RFC.