Zone Routing Protocol

Intra-zone protocol (IARP) operates within a zone and learns all the possible routes, proactively. So, all nodes within a zone knows about its zone topology very well. Inter-zone protocol (IERP) is reactive and a source node finds a destination node which is not located within the same zone, by sending RREQ messages to all border nodes. This continues until destination is found.

Routing zone diameter is variable and this should be chosen optimal for a scaled topology. By zoning, control message overhead is attempted to be lowered. Current zone size estimation techniques allow ZRP to operate within 2 percent of the control traffic from optimal value.

The code is available under the GPL license.

Extract from internet draft

The hybrid Zone Routing Protocol (ZRP) framework can adapt to a wide variety of network scenarios by adjusting the range of the nodes' proactively maintained routing zones. Large routing zones are preferred when demand for routes is high and/or the network consists of many slowly moving nodes. In the extreme case of a network with fixed topology, the ideal routing zone radius would be infinitely
large. (Consider the purely proactive routing protocols used on the fixed Internet). On the other hand, smaller routing zones are appropriate in situations where route demand is low and/or the network consists of a small number of nodes that move fast relative to one another. In the "worst case", a routing zone radius of one hop is best, and the ZRP defaults to a traditional reactive flooding protocol.

When the ZRP is properly configured for a particular network scenario, it can perform at least as well as (and often better than) its purely proactive and reactive constituent protocols. In situations where the network behavior varies across different regions, the ZRP performance can be fine-tuned by individual adjustment of each node's routing zone.

The global reactive component of the ZRP uses the multicast based "bordercast" mechanism to propagate route queries throughout the network efficiently, rather than relying on neighbor-broadcast flooding found in traditional reactive protocols. Consequently, the ZRP provides the most benefit in networks where reliable neighbor broadcasting is either inefficient or altogether impossible. In particular, the ZRP is well suited for multi-channel, multi-technology routing fabrics and networks operating under high load.

Reference

• The information is taken from ZRP page under the Copyleft license
• INTERNET-DRAFT