Zone Routing Protocol

Zone Routing Protocol or ZRP was the first hybrid routing protocol with both a proactive and a reactive routing component. ZRP was first introduced by Haas in 1997. ZRP is proposed to reduce the control overhead of proactive routing protocols and decrease the latency caused by routing discover in reactive routing protocols. ZRP defines a zone around each node consisting of its k-neighbourhood (e. g. k=3). In ZRP, the distance and a node , all nodes within -hop distance from node belongs to the routing zone of node . ZRP is formed by two sub-protocols, a proactive routing protocol: Intra-zone Routing Protocol (IARP), is used inside routing zones and a reactive routing protocol: Inter-zone Routing Protocol (IERP), is used between routing zones, respectively. A route to a destination within the local zone can be established from the proactively cached routing table of the source by IARP, therefore, if the source and destination is in the same zone, the packet can be delivered immediately. Most of the existing proactive routing algorithms can be used as the IARP for ZRP.

For routes beyond the local zone, route discovery happens reactively. The source node sends a route requests to its border nodes, containing its own address, the destination address and a unique sequence number. Border nodes are nodes which are exactly the maximum number of hops to the defined local zone away from the source. The border nodes check their local zone for the destination. If the requested node is not a member of this local zone, the node adds its own address to the route request packet and forwards the packet to its border nodes. If the destination is a member of the local zone of the node, it sends a route reply on the reverse path back to the source. The source node uses the path saved in the route reply packet to send data packets to the destination.

References

*Haas, J., 1997, “A new routing protocol for the reconfigurable wireless networks”, Proc. of IEEE 6th International Conference on Universal Personal Communications 97, pp. 562-566
*The information is taken from [http://www.zrp.be/ ZRP page] under the Copyleft license
* [http://people.ece.cornell.edu/%7Ehaas/wnl/Publications/draft-ietf-manet-zone-zrp-04.txt The ZRP internet-draft] (copy at Cornell)
* [http://www.ietf.org/proceedings/02nov/I-D/draft-ietf-manet-zone-brp-02.txt The BRP internet-draft] (copy from IETF proceedings)