Advanced Routing Gspr

3.

What is the history and what were the driving factors behind the development of the GSPR routing protocol?

4.

What is the industry acceptance and view of this protocol?

Greedy Stateless Perimeter Routing is a protocol used within a dynamic sensor environment to establish connections between nodes which are inherently limited in both computational and power resources. The problem with this is that sensor nodes which use protocols such as greedy stateless perimeter routing are used in an ad-hoc fashion in which multiple nodes may have to communicate with each other before reaching a wired infrastructure. This creates the problem of not having a router or other type of forwarding device between nodes, thus forcing each node to do its own routing and forwarding, based on the protocol which is implemented on it [2]. Combined with the flaws that come with using Distance Vector or Link state routing methods, there was a need to develop new protocols to use in mobile sensor routing and enable a multi hop environment to function efficiently. In a distance vector network, it is common practice to share routing information with neighbors so that routing tables within immediate neighbors will be the same and up to date based on what each of them receives from the other. While this works quite well for wired routing and even single hop wireless network, in a mobile network the constant movement of nodes and change in the topology leads to shortcomings in the distance vector protocol, mainly being that routing tables expire and become inaccurate within a rather short amount of time (Karp, Kung). On the other hand, because link state tries to map the entire network to which it is a part of and then inform all nodes on the network, it too has an issue, but quite the opposite of distance vector. Link state will send out discovery messages at a timed interval to ensure the network topology it has in its database is correct, but will find a change in the network almost every time it does so because of the network’s mobile property. Therefore, there will be a constant flood of topology changes within the network, leading to the exhaustive

power consumption of each node, merely to receive, process and store these changes within its link state database. Obviously, the cases demonstrated will not work for such a dynamic sensor array and thus spawned the development of greedy stateless perimeter routing (GSPR). When wireless sensor networks first started being used, a proposition of using caching methods similar to that of caching internet pages for quick use by web browsers, was given and spawned the creation of a number of different protocols to utilize this method. This method allowed for sensors to request an update on demand from other sensors to which it plans to send its payload and expect to forward onward. This makes it so that nodes are not being flooded with messages, but when requested provide other nodes with their routing tables and in a timely manner will update their own databases to allow for the forwarding of packets through them. This update will occur if a timer has expired on the next request for the node to forward on a packet. GSPR has mainly been proposed for three types of network in which its developers thought that it would work best. The first and most prominent is ad-hoc networks in which there is no established backbone network or any sort wired infrastructure to affix nodes to. This can be any number of situations including disaster recovery or rescuer needs, military operations in areas which may not have any sort of network ability, or conferences in which a backbone network is unavailable or just cannot handle to load of as many computers connecting to it as desired. The second proposed use for GSPR is sensor networks in which sensors talk to each other over multihop systems and relay messages to computer for forest fire tracking, weather system prediction or automated tasks. GSPR is especially helpful in these sorts of situations because of the limited amount of communication range and power that these nodes usually have due to their limited size and portability. By using GSPR in this specific situation, it can be useful based on the less need for power, but rather only when the node is needed.

The final proposed use for GSPR is rooftop deployment, a common practice within large metropolitan areas to avoid the need for installing wireless access points throughout buildings and city establishments. The antennas used for rooftop deployment enable a city to deploy a metropolitan area wireless network, such as the one used in San Francisco, California, without a need for access points to be installed on a wired infrastructure, thus requiring a larger amount of equipment and a wired network within residential and privately owned establishments.

GSPR is used in industry when it comes to mobile sensor systems, such as GPS, but is seen as inherently insecure. When used in the real world, GSPR scans for adjacent neighbors which can ensure that packets will reach their destination. This is done by calculating the distance between the source and second node in the neighborhood and that neighbor to the destination. When transferring packets between each node, there is the ability for each node to modify the packet due to having to process and forward the packet onto the next node in the sequence which it will follow to get to the destination. There have been a number of alternatives proposed to fix this such as [getpdf.pdf] which uses a sort of count mechanism built right into the packet itself and increments itself if the packet is unmodified or decrements otherwise. Industry views on the protocol in general are that it is generally scalable and usable within a relatively small network of around 50 nodes. Once this threshold is passed, issues arise based on link state databases growing too large for the sensor to handle and transmit without a degradation of power and time it takes to transmit the message. There is also the view that GSRP allows for robust deliverance of packets, but this is sometimes affected by sensors interfacing with different powered radios. Because GSRP allows for the use of GPS within the nodes which it connects, it

seems that it will increase in popularity as more sensors are added to cars and in metropolitan areas to interface between nodes [3][4]. [1] http://www.eecs.harvard.edu/~htk/publication/2000-mobi-karp-kung.pdf [2] http://delivery.acm.org/10.1145/290000/288256/p85-broch.pdf? key1=288256&key2=9205899321&coll=GUIDE&dl=GUIDE&CFID=30791844&CFTOKEN= 27421436] [3] http://www.cs.ucl.ac.uk/staff/B.Karp/geochal-dimacs2001.pdf [4] http://www.cs.ucl.ac.uk/staff/B.Karp/gpsr/ [5] http://wiki.uni.lu/secan-lab/Greedy+Perimeter+Stateless+Routing.html [6] http://whitepapers.zdnet.co.uk/0,1000000651,260283827p,00.htm [7] http://ieeexplore.ieee.org.ezproxy.rit.edu/stamp/stamp.jsp? tp=&arnumber=4444087&isnumber=4444031