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A number of strategies have been defined to reduce the routing decision process that occurs at each router when a datagram travels the hop-by-hop route between source and destination. ARIS is one of those schemes. It is not as much a flow-driven scheme like IP Switching, but a tagging/labeling scheme like MPLS (Multiprotocol Label Switching) and Cisco's Tag Switching.

ARIS is IBM's scheme for switching IP datagrams. It is normally associated with ATM networks, but ARIS can be extended to work with other switching technologies. ARIS (and other IP switching technologies) takes advantage of integrated router switches. The idea is to map routing information to short fixed-length labels so that next-hop routers can be determined by direct indexing, rather than using the standard router packet evaluation and lookup process.

What ARIS does is set up a virtual circuit through a network based on the forwarding paths already established by routers that use routing protocols such as OSPF (Open Shortest Path First) and BGP (Border Gateway Protocol). IP datagrams are then switched through the network following these paths. No routing is done by any device along the VC. Instead, the datagrams are "tagged" with a label that is read by intermediate switches along the way, identified with a particular destination network, and sent along the appropriate circuit to that destination.

ARIS is very similar to MPLS. At the time of this writing, MPLS appears to be the major focus of the industry and is an emerging IETF standard. See "MPLS (Multiprotocol Label Switching)" and "Multilayer Switching" for more details.

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