IIP for wireless communication

zyx zyxwvut zyxwvutsr IIP for Wireless Communication Kirti Keshav and Venkatarani P ECE Department Indian Institute of Science Bangalore, 5600 12 INDIA 080-293-2282 kirti Oprotocol.ece.iisc.ernet.in, pallapa@ece.iisc.eriiet.in zyxwvuts Ahsrrcict-Th is paper proposes I IP( I ntel I igent Internet Protocol) which effectively addresses the issues involved in wireless communication at Network Layer such a s support for mobility, frequent loss of connection due to fading, handoffs and security. We have chosen to use Intelligent Agent technology for our architecture of 1IP because it provides desirable properties such as Speed-up and Efficiency, Robustness and Reliability, Scalability and Flexibility, Development and Re-usability. We make use of .four Intelligent Agents namely Principal Agent(PA), Agent for Address Resolution and Mobility Support(AARMS), Agent for Error Handling a n d Recovcry(AEHR), Agent for Network Security(ANS) and design each Agent bused on BDI(BeliefDesire-Intention) Architecture. A variant of Blackboard architecture is used for inter-agent communication. Special carc has been taken to make proposed IP compatible with existing Networks. The proposed work has been simulated and verified for its operational effectiveness. While designing the architecture for Intelligent IP, we had four important design ob.jectives, to make our IP really intelligent cnough to solve the problems in wireless communication efliciently. This paper presents tlie nrchitecture of Intelligent IP b x c d on following design objectives: Intelligent Agent based 1P has to be backward compatible with existing networks, i.e., it must handle all the existing ne twork tratli c successfii I I y. Intclligent IP has to be Rexible; for example, various functionalities of Network layer such a s security. support for mobility are to be evoked only when necded i n order to avoid excessive processing. Better cooperation und coniinunication between protocol layers are key requirements for improving Internet protocol performance in future. Hence. we have to design in such ;I f;isliion that later on TCP functionality can be added to form ;I coinpletc 11' stack, based on layer less architecture using Intel I igent Agcnts. Rapid development of new protocols. I n future new protocols would be implemented quickly by adding Agents with new functionnlities ;is required by new protocols. . . 1 zy zyxwvut zyxwvutsrq zyxwvutsr 1. INTRODUCTION Dcsigii ol?jcctivcs I Phnitrl lledir Figure 1. A typical Comm~inicationScenario 2. THEPROPOSED INTELLIGENT IP wI R ELES S c0M M UNI CAT I ON FOR In our proposed IP, we make usc of four Agents. Each individual Agent follows BDI Architecture as an internal model. Every Agent is able to sense the environment i.e., perceptions are same for all the Agents. The IIP is intelligent in tlie sense that it learns from the environment dynamically and takes the best decision on the basis of present and past state information, among the various options available. A brief description of each of the four agents is as follows. First Agent,whicli we name as Principal Agent(PA), takes care of normal 1P functionality. It's possible actions include passing of arrived packet to tipper layer protocol if destination of packet is host itself, forward packets to appropriate next hop if packet is meant for another host. Second Agent, coined a s Agent for Address Resolution and Mobility Support(AARMS), handles all addressing related issues of IP layer. I t is responsible for maintenance of routing tables. If the environment is of Wireless type, then this Agent makes sure that hantloffs and frequent temporary loss of connection i n wireless link doesn't affect the upper layer coiinectioiis. It c u i use Mobilc IP for macro mobility (slow handoffs) a n d either ccllulnr IP or Hierarchical Mobile IP in case of micro mobility(fast handfiffs) to avoid excess signaling overhead. If other Agents need any information regarding IP addresses, they send request to this Agent. Packets corresponding to various Routing protocols such as RIP, OSPF, BGP are also to bc handlecl by this Agent for maintnin- zyxwv zyx zyxwv zyxwvu zyxwv zyxwv TENCON 2003 / 1540 BDI ARCI-III‘ECTCJRE: W I T H I N EACH AGENT BDI architcclures I I I ;ire pl’ncticnl rcxoning iirchilectures. i n 3. U S E OF . which the process of cleoitling what t o do rcsembles the kind 01. prxticnl reasoning t h a t we appear to use i n our evcryday lives. The basic eoniponciits of ;i BDI architecture are data struckires representing the bcliels. desires. and intentions of the ;igent. ancl I’iiiictions that rcpresent its deliberation (tlecicling what intentions to have - i.e.. deciding what to do) and means-ends reasoning (deciding how to do it). Intentions play ;I central role in the BDI inodel: they provide stability for decision making. ;incl act IO focus the agent’s prncticiil reasoning. zyxw zyxw zyxwvutsrq We clioose BDI Architecture ;IS ;in internul architecture tor each agent mainly l‘or two reasons: . - -. I : ,i , : j ,’ . ~ ... . ._ .. . . - ....... ... .... . ’ Figure 2. Intelligent IP for Wireless Communication ing routing tnbles. I n future routing protocol corresponding to Ad-Hoc wireless network are also to be handlccl by this Agent. Third Agent. termcd a s Agent for Error Handling and Rccovery(AEHR). is responsible for handling 01’ various error situations. It handles all ICMP traftic and takes appropriate actions in fesponse t o it. It also helps AARMS. i n niaintaining routing information. For example. when ICMP Redirect message comes. suggesting ;I better next hop uclclrcss to destination. it gives this information to AAKMS. Fourth Agent. Agent for Network Sccurity (ANS). In Wireless Communication. since data is transmitted in open medium. security o f data is extremely necessary. This Agent mainly takes care of all the ‘four aspects of Network security.i.e.. Secrecy. Authentication. Non-repudiation and I n tegrity Control. Currently. we propose to inlike use of IPSec protocol. Depciidinf upon the current beliefs ancl intentions, it decides regarding which of the two types o f security a \ gorithms. symnietric encryption algorilhriis (e.g. I h t a Encryption Standard- DES) and One-way hash funclions (e.g.. Message Digest MD5 and Secured Hash Algorithm SHA-I ). as recoinmended by IPSec protocol, is to be used. IPSec also provides-waysto sectirc tunnels against false data origins, and encrypt traffic agninst unwanted network passive or active intruders from listening or modifying actions. Authentication, which is used for granting user x c e s s to corporate network and Encryption which is used t o transfer user critical infornlation through unreliable medium of the IP network arc the most important aspects which iire to be taken care of. In addition. Principal Agent also acts as the fiicilitator that manages interaction between Agents for inter-agent communication. I t is intuitive - we all recognizc the process of deciding what to do and then how to d o it. and we all have an inforinnl understanding of the notions of belief, desire. ancl intention. It gives LIS ii clear functionnl decomposition, which indicxtes what sorts of subsystems might he required to build iin Agent. Decisiou tiicrkiirg pi.occ~.s.s ?/‘cwcIi Agcwt I f S is an arbitr;uy set. then zyxwv b4S) power-se, of S, ‘rile stateof n,oment is, il (13.D,I), is B D I A~~~~ i,t any givel, U C B e l , D C D r : s , r i i ~ r l IC l r r t An Agent’s belief revision function is :I mapping IWJ : t:,( Bel) x P --f p(Br4) which on the basis of the current percept and current beliefs dctcrinines a new set of beliefs. The option generation function. riptioris. maps ;I sct of beliefs and a set of intentions to a set of desires. fq’tio/ts : (.>(DC,l) x p ( Z d ) -+ $,(DCS) The purpose of optiotis function is basically to perform means-ends reasoning with additional constraints of being con.ristenf. A BDI Agent’s deliberation process (deciding what to do) is represented i n the,fiho. function. Jdtf!?’ : gJ(Bf!/) x (,l(I./j,/,) G)(I//,t) &,(nCS) x which updates the Agent’s intentions on the basis of its previously held intentions. ctirrent beliefs iind clesires.,filtn should satisfy the following constraint: VB E $’(BiCl),VDE p(Dcs),VI E K>(ZUt) \ zyxw zyxwvu zyxwvuts zyxwvutsr zyxwvutsrqponm zyxwvutsrqponmlkji zyxwvutsrqpo Poster Papers / 1541 jiltcr(L?, D , I ) c I U D . In other words, current intcntions are either previously held intentions or newly adopted options. The exrciite function will then return executable intentions which correspond to directly executable actions: The Agent decision function, ac/ior?of a BDI Agent is then a function nctiolls : P --f .4 and is defined by the following pseudo-code. function action(p: P):A begin B := /v/(B,p) D := optio~s(B,I) 1 :=/?Ikr(B,D,l) return e.uxote(1) end function action Figure 3. Inter Agent Communication 5. IMPLEMENTATION OF IIP zyxwvutsrq Sorrie Beliqji o/'llP :v Agents All Agents share set of common beliefs. Here is a small set of coininon bcliefs which are useful at network layer. Whether communication is over wireless or wire-line link can be known by the IP addresses of communicating hosts. Loss rate Rate of environment change Security required or not Type of Application-Multimedia or Data Centric System related facts - Buffer space available - Processing power available 4. METHODOF INTER AGENT C OM M U N ICATI ON I n proposed architecture, communication between Agents is achicvcd using a Blackboard consisting of four regions, which are divided among four Agents. Each Agent has its own region, where it can write. But every other Agent has permission to read i n memory areas of other agents. Due to this mechanism, every Agent knows what other Agents has to say. Synchronization among Agents is achieved by making tise of global flags. Above scheme has been implemented using shared inernory concept. Each of the Agent has been implemented using different process. A set of four memory areas are created by Principal Agent. Then these memory arcas are attached by other Agents to their process address space. Proposed lntelligent 1P is implemented at Application layer in Linux Machine. Linux kernel implcments a generic-purpose protocol, called PF-PACKET, which allows us to create a socket that receives packets directly from the network card driver. Hence, any other protocols handling is skipped, and any packets can be received. Using this PFPACKET Socket facility, we are able to bypass the tistial TCP/IP stack and receive the Ethernet frames directly at the Application layer. Since presently we are concentrating. on IP layer only, at Transport layer we are using U.DP. Advnntuges y f iniplenienting IIP ot Application I q w PF-Packet Socket type through which we are able to receive packets directly at Application layer is ;I stantlard socket type, which is available on all Unix machines, so our implementation is portable on all Unix machines. At Application layer, we have access to facilities of modern high level language constructs. We are using facilities such as shared memory and processes. Each of our Agent is implemented as a process and to coinmunicate among themselves, they use shared memory. Now we present some case studies, to give an idea of how IIP reacts intelligently to different environment scenarios at network layer. Case Stirdies Each Agent in the.system, gets the common perceptidn from the environment. But since intentions of different Agents differ, each Agent responds independently to an event and update> itself with new options and intentions for future de- zyxwv zyxwv zyx zyxwvut TENCON 2003 / 1542 care-of-address and it should now receive tunneled packets with new care-of-address. Case 6: If a mobile node is about to make handoffs, then AGENT3 takes action by stopping the data transfer for a brief interval and start buffering the data being transferred. After hantl-off has been completed. normal data transfer is resu nied. Case 7: Similarly if Agents sense from :the environment that link quality is poor due to fading effects, then system starts taking precautionary measures by reducing the data transfer rate and buffering the data being transrnitted, so that even if some packets are lost, they can be retransmitted locally only, instead of from the original sotirce. 6. WIRELESSNETWORKSETUP & EXPERIMENTS \ i zyxwv zyxwvutsrqponm We used the Wireless Network Setup as shown in Figure 4. Experiments were perfoinetl using the machines namely EOD. WLAN and JALAW. While WLAN is connected to network with both wireless and wireline link, JALAW is having only wireless link with network. Processing T h e zyxwvutsrqpo As a benchmarking test, an ICMP ECHO REQUEST coming Figure 4. Wireless Network setup cision. To make our implementation compatible to existing TCP/IP structure, we support 161, [7] and RFC79l(for IP). Case 1: Usual IP traffic is being received by our Intelligent IP and buffer overflow occurs in receiver's memory. Then AGENT3 sense this perception from environment, and sends ICMP-SOURCE-QUENCH message to sender. Case 2: While receiving data if Agent? finds that 1P is not able to pass on the packets further, it sends back ICMP-UNREACH type message. Case 3: If IP sends data and some intermediate router finds that better route is available then router sends an ICMP-REDIRECT message containing the address of better router. So, Agent2 will get this information from Agent3 and next packet onward AGENT1 will send packets with destination address mentioned in redirect message. Case 4: If some intermediate hop finds ,that something is wrong with the header field of IP packet than i t sends the source an ICMP-PARAMPROB message. On receiving of this message AGENT3 tries to locate the error and rectify it. Case 5: If mobile node moves to a new network, AGENT2, which is responsible for address related issues , senses this event and initiate procedures to acquire care-of-address, so that mobile node can receive packets from Internet hosts without losing existing connections. After acquiring new care-ofaddress Agent2 intimates AGENT1 that it has received new from the EOD is received by WLAN and in response,WLAN generates an ICMP ECHO REPLY and send it buck. The test was made by varying the size of payload on ECHO REQUEST message. When each message arrives or departs. the time was noted down with micro-seconds resolution at WLAN. Following graph depicts vuriation of average processing time with variation in payload size o f arriving packets. Input Proccsinf Time \ < P;iglintl Sizc linuw Kcriirl + z I .t. . . . . . 0 t . t .. I 0 200 400 600 XIN) I I INMI I?W 1400 Paylu;id Six Figure 5. Average Processing Time for Incoming Packets We can see that our Intelligent Agents based IP implementation's overall processing time for incoming packets is slightly more than that o f Linux kernel's protocol stack implementa- zyxwvut zyxwvu zyxw .. - Poster Papers / 1543 tion. Following reasons can be attributed to this phenomenon. We have implemented our Intelligent Agent Based IP at user level in Linux. So when a packet arrives at the Ethernet interface. kernel always gets the priority to handle packets over any other user process[lO]. Because of this, even though our Agent Bused IP receives packet directly from Ethernet interface, it gets packet after some delay. For transmitting the response packets also, since we are using PF-PACKET Socket facility, again user level process, which is obviously a slower method to transmit than the way kernel’s TCP/IP stack does. From the results obtained, we can conclude thnt our Intelligent IP for Wireless Communication is compatible with existing TCP/IP stack and even though we have implcinentetl our architecture at user level i n Liniix, thereby not having.the advantage of faster handling of clata as compared to Linux kernel, overall processing delays arc coniparable to existing TCP/IP implementation of Lintix kernel. Also our Agent based architecture has atlcled advantage of bcing flexible. scalable and reusable. as more Agents can be added easily as and when new requirements arise. zyxwvutsrqpo zyxwvutsrqponmlk zyxwvutsrq zyxwvuts Rotiucl E.@ firtie This test is to see average round trip time available with our implementation over il wireless link of bandwidth 2MBps. From EOD to JALAW on a 2 MBps Wireless link, we transmit ECHO-REQUEST message with varying payload. Both Server and Client are using our Intelligent Agent Based 1P. REFERENCES Gerhard Weiss, “Multiagent Systems: A Modern Approach to Distributed artificial Intclligencc.” The MIT Press, Massachuseiis. http://www.computer.org/in ternet/v4n I/joy.htm M. E. Bratman, “lntentions, Plans, and Practical Rea- son,” Harvard University. Press: Cambridge, MA. 1987. P. E. Agre and S. J. Rosenschein, “Comptitationnl Theories of Interaction and Agency,” The MIT Press: Cambridge, MA, 1996. M. Wooldridgc, “’Agent-based software errgineering,” IEE Eunsrrctioiis o r 1 S o / t i t w e Gigiirewitig, 144( 1):2637, February 1997. RFC793, T.Socolofsky, C.KaleA. “Transmission Control Protocol,” September. 198 I . zyxwvutsrqponmlk RFC792, J.Postel, “Internet control Message Protocol.” September, I98 I . 0’ Glitho, R.H., Magedanz, T.. “Applicability of Mobile Agents to Telecommtinications,”lEEE NetMW/.li.Vol 16, Issue 3, May/Jun 2002. Stuart Russell and Peter Norvig, “Artificial IntelligenceA Modern Approach,” Pearson Education. 2001. M.Beck, H.Bome, M.Dziadzka, U.KuniW, R.Magnus, D Verworner. “Linux Kernel Intcrnnls,” AddisonWesley, 2000 zyxwvut Figure 6 . Round Trip Time for Packets with varying payload The round-trip time estimation is il critical part of TCP, since the estimated round-trip time is used when determining ii suitable retrmsmissioii ti me-oiit . As one can note that we are able to achieve very less R T T (6-7 ms) with smnll packets, which shows that once TCP functionality is implemented. our Intelligent agent based IP would be able to handle interactive applications like Telnet, where response time upto 1501nsis acceptable. 7. RESULTS& CONCLUSION We have deployed IIP in real-time TCP/IP environmenl where several FTP transactions, Multimedia stream transfers, etc., are taking place.To test our implementation, we performed various experiments and compared the parameters such as average processing time and round trip time.