Internet Indirection Infrastructure

This paper describes an overlay network for multicast, anycast and mobility services.

Summary

This paper addresses the issues of supporting multicast/anycast on current networks. The Internet is designed for point-to-point connections so adding true multicast is hard. Current approaches require the sender to know a list of recipients and the recipient locations to be fixed. The proposed design logically /decouples the act of sending from the act of receiving/.

The mechanism is to have receivers register interest in a particular type data. This is done with a "trigger" consisting of a (id, address) pair where the id is an m-bit identifier. When a sender sends a packet with the specified id, the packet is forwarded to all receivers that registered triggers.

To generalize the identifier matching the system forwards packets if

1. The ids have a prefix match of at least k bits and
2. There is no trigger with an id that has a longer prefix.

Mobility is supported by allowing receivers to register a new trigger with a different address. Multicast is supported by having a group of triggers with the same id. Anycast is supported by having a group of servers with triggers that are identical in the k most significant bits. All other bits of the ids are different, thus the matching mechanism will pick the single server with the longest prefix match.

Thoughts

This paper describes a clever way to build in support for multicast, anycast and mobility in an overlay. The core of the idea is quite simple: add a layer of indirection where receivers must register. In some sense this sounds similar to the mobile IP model of having a representative node that forwards packets to one's real location.