FASTEST METHOD TO FIND ALTERNATIVE RE-ROUTE

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1 INTERNATIONAL JOURNAL OF RESEARCH IN COMPUTER APPLICATIONS AND ROBOTICS ISSN FASTEST METHOD TO FIND ALTERNATIVE RE-ROUTE 1 M.JothiLkshmi, M.S., M.Phil. 2 C.Theeendr, M.S., M.Phil. 3 M.K.Pvithr, 4 S.Yuvrthi Asst. Professor 1+2, Reserh sholr 3+4, Deprtment of Computer Siene, Viveknndh College Of Arts & Sienes For Women (Autonomous), Elymplym, TmilNdu, Indi Astrt Routing is the onept of sending the pkets from the soure to destintion through the ertin pths. In some ses efore the Interior Gtewy Protool (IGP) there my e link filure etween the soure nd destintion. To reh the trget the regionl su network servie provider enountered to find new pth whih lredy exists. Certinly multist nodes re involved nd spre links re used. In our sheme Ring Topology re used to overome the single pth filure. We illustrte the method nd prove tht it will find pth if one exists. Keywords: Ring Topology, Routing Protools, Alternte Routing, Interior Gtewy Protool, Node Filure. 1. INTRODUCTION A Routing Protool selet route etween two nodes on omputer network. Eh router hs priori knowledge out the networks tthed to it diretly. A routing protool shres this informtion first mong immedite neighours, nd then throughout the network. This wy, routers gin knowledge topology of the network. Consider soure node s sending dt to destintion node d.suppose some link (i, j) on the shortest pth from s to d fils. An IGP will find n lternte pth from s to d tht voids (i,j). To overome this we implementing Ring Topology network in whih eh node onneted with to other nodes to provide ontinuous pth etween soure nd destintion. If ny one of node is filure or rek, the lterntive route or multipth n e introdued. The soure-speifi multist is the simplest model for multist where soure node is fixed nd the reeivers will never send dt to the multist. Any filed link in the pth will disrupt the servie to some nodes. The numer of nodes ffeted ould e very lrge espeilly when the filure is t the proximity of the root node. The stndrd solution is to reonstrut the multist node fter link filure is deteted. The fst reroute restores the multist node without route re-onvergene nd therefore, shortened the disruption. This sheme pre instlls nother set of routes on eh multist routers. 2. BODY TEXT 2.1. Filure reovery Tehniques developed for fst reovery from single-link filures provide more thn one forwrding edge to route pket to destintion. Whenever the defult forwrding edge fils or pket is reeived from the node S. Y u v r t h i e t l Pge 41

2 tthed to the defult forwrding edge for the destintion, the pkets re rerouted on the kup ports. In the uthors present frmework for IP fst reroute detiling three ndidte solutions for IP fst reroute tht hve ll gined onsiderle ttention. When forwrding link on tree fils, the pket my e swithed to the other node. Types of filure: i) Link Filure Figure 1: Link Filure ii) Node Filure 2.1. Fst re-route method Figure 2: Node Filure We now present the detils of the method. Let G = (N,A) e n undireted onneted grph with node set N nd r set A. For x N, let N(x) e the set of neighors of x, where neighour of x is node one r wy from x. We ssoite with eh undireted r (i, j) A ost (i, j), nd require eh (i, j) to e positive integer. (The integer vlued restrition n lwys e met y pproximting, to the desired ury, eh r ost y n improper frtion, nd then multiplying ll the frtions y the lest ommon multiple of the frtion denomintors.) For i, j N, let _(i, j) e the ost of the shortest pth in G etween i nd j. When using Route(s, d) for fst re-route in the event of n r filure, whih is the trget pplition, _(i, j) represents the shortest pth ost efore the IGP hs re-onverged in response to the link filure. S. Y u v r t h i e t l Pge 42

3 f e d Figure 3: Fst Reroute Soure:, Destintion:, Filed Pth:, Re Route Pth: d Multipth routing Multipth routing is promising routing sheme to ommodte these requirements y using multiple pirs of routes etween soure nd destintion. Multipth routing is the routing tehnique of using multiple lterntive pths through network, whih n yield vriety of enefits suh s inresed ndwidth, or improved seurity. The multiple pths omputed might e overlpped, edge-disjointed or node-disjointed with eh other. Extensive reserh hs een done on multipth routing tehniques. d e g f Figure 4: Multipth Routing Soure:, Destintion: g, Filed Pth: g. Multipth: 1 st pth is --e-f-g 2 nd pth is --d-e-f-g Method Proedure Route(s, d) 1 initilize: P = 0, Δ(n) = 0 for n N, nd x = s; S. Y u v r t h i e t l Pge 43

4 2 while (x _= d) { 3 Let Y = {y N(x) Δ(y) = min n N(x)Δ(n)}; 4 Pik ny y Y for whih the sum C (x, y) + *(y, d) is smllest; 5 Set Δ(x) Δ(x) + 1, P {P, x}, nd send the pket nd P from x to y; 6 Set x y; 7} Explntion: Let s nd d e the soure nd destintion whih is onneted to direted grph with node N. If x N then x is node wy from r (i, j). The r should e positive integer. If i, j N then ost is *(i, j) e the shortest pth. If the route s, d is used for fst re-route in r filure the trget pplition, *(i, j) represents the shortest pth ost efore IGP. If route (s, d) < p then order of list node hve to visit p {p,x} mens tht x is inserted fter the rightmost element in P. Also, (n) is the multipliity of node n, inditing how mny times n hs een visited y the urrent pket. Figure 5: Finding re-route with low ost Soure: f, Destintion:. Filure pth: f-e--. Aville pth: 1 st pth: f-e---=15. 2 nd pth: f-e--d-=14. The 2 nd pth is the shortest re-route pth from soure to destintion with low ost. 2.5 link filure lgorithm desription In our lgorithm is sed on sequentil serh in the primry link, whih we ll SS LINK. It ontins the following steps. 1) Init: Set the kup port of eh node to null, i.e., n = 0(n = 2; : : : ;N). S. Y u v r t h i e t l Pge 44

5 2) Explore the primry link T(1) using depth-first serh. For eh node n (n = 2; : : : ;N), ssume its primry port pn fils (i.e., link n! pn fils) nd do the following: ) If n 6= 0, the kup port of node n is lredy found, go k to step 2 to proess the next node; otherwise, ontinue to the next step. ) The filure disonnets su-link T(n) from the primry link, where n is the root of the su-link. Dye the nodes in T(n) lk nd ll the other nodes in the topology white. The forwrding pth from eh white node is not ffeted y the filure. ) In T(n), use redth-first serh to find the first node i tht hs diret link to white node j, set its kup port i = j. We ll this port i,j n exit of su-tree T(n). d) If i n, find the pth from n to i in T (n). Suppose the pth is n -> m1 ->m2 ->ml -> i. Set the orresponding kup ports s n = m1, m1 = m2,., ml = i. Go k to step 2. Figure: 6() Primry nodes, 6() Filure 2-1 6() filure 7 5, 6(d) filure 9 7. Figure 6 shows the proedure of using LINK on the depth-first serh pth ) Filure 2 1 dethes su-tree T(2) from the primry link. Using redth-first serh, n exit 5-> 6 is found nd the rerouting pth is 2->5->6. Thus, we set 2 = 5 nd 5 = 6 (Figure 6()). 2) Filure 5 2 retes su-tree T(5), the serh is skipped sine ) Filure 7 5 dyes T(7) lk, nd the serh immeditely yields 7 = 4 (Figure 6()). 4) Filure 9 7 dyes T(9) lk, the lgorithm sets 7 = 4(Figure 6(d)) Algorithm properties optimlity Theorem 1: LINK minimizes the numer of swithovers in (1) if the primry tree is otined using minimum hop routing. Proof: When the primry port of node k fils, the exit of T(k) is found using redth first serh. Therefore, the hop ount from node k to the exit is minimized (sine the primry tree is sed on minimum hop routing). This minimizes the numer of swith-overs euse hoosing ny other exit requires more nodes to use kup ports. Sine LINK minimizes the numer of swith-overs under ny possile filure, it hieves the optimlity in (1). Complexity: The lgorithm hs low omputtion omplexity. Although it ontins two nested serhes in the tree, the CPU yles onsumed y eh step is very limited. In step 2, node is immeditely skipped if its kup port is S. Y u v r t h i e t l Pge 45

6 lredy found. In step 2, the lgorithm only heks if node hs white neighor,thus requires very little omputtion. In step 2d, the pth from n to i is extly the reverse of the primry pth from i to n, whih does not require omplited route lultion. In prtiulr, eh router only runs prt of the lgorithm when link is implemented in distriuted mnner. For node n, it finds its kup port n nd stops immeditely. Denote the primry pth from node n to node 1 s n-> yl->yl->1-> -> y1->1, the omputtion is simplified y repeting step 2 to 2d from y1,.. yl; x. Further omplexity redution n e hieved y first, do not reord other nodes kup ports; seond, jump long the serh pth. For exmple, when node 7 in Figure 6 lultes its kup port, it only serhes long When node 2 finds n exit through node 5, the serh jumps to the next node on the serh pth, whih is node 7. Menwhile, it is not neessry to reord the kup ports of node 2 nd RESULT AND DISCUSSION These re ritil performne metris of fst rerouting euse they hve signifint impt on router-to-router dely, ongestion, nd network effiieny. We ompre our shemes with shortest pth route relultion to see the differene of the performne metris. The topologies dopted in our evlution inlude severl prtil networks nd rndomly generted ones. The results show tht our shemes hve onsistent performne in vrious networks. When ompre with the other onepts nd solution we hve four dvntges. (1) The multist tree n e ritrry. (2) There is only miniml disruption nd there would e no pket loss. (3) Filure protetion is ville to wider set of network topologies. (4) Only smll numer of multist nodes re involved nd the numer of spre links used is lso smll. (5) The shemes hve low omplexity nd n e esily pplied to prtil networks to sustntilly shorten servie disruption used y filures 4. CONCLUSION The results show tht our shemes provide lmost the sme effiieny s route relultion regrdless of the node degree. In ddition, we test our shemes in ring topology nd find tht they generte muh higher overll trffi volume ompred to route relultion. Finlly, our sheme is designed for link-stte routing protools, it is interesting to study the extension of the shemes for re routing so s to enhne the survivility of interdomin routing. S. Y u v r t h i e t l Pge 46

7 5. REFERENCE [1] Atls, Ed., U-turn lterntes for IP/LDP fst-reroute, IETF drft tls -ip lol-protet-uturn-03, Fe [2] Atls nd A. Zinin, Eds., Bsi speifition for IP fst reroute: loopfree lterntive, IETF RFC 5286, Sept [3] P. Domshitz nd M. Siegel, Dul ring usge in FDDI, Computer Communitions, vol. 15, no. 7, pp , [4] A Fst Re-Route Method Eri Rosenerg nd Jmes Uttro, Memer, IEEE trnstions on networking yer [5] S. Ri, B. Mukherjee, nd O. Deshpnde, IP resiliene within n utonomous system: urrent pprohes, hllenges, nd future diretion. [6] G. Shen nd W. D. Grover, Extending the p-yle on onept to pth segment protetion for spn nd node filure reovery, J. Sel. Ares Comm., vol. 21, no. 8, ACKNOWLEDGEMENT This reserh pper is mde possile through the help nd support from everyone, inluding: prents, tehers, fmily, friends, nd in essene, ll sentient eings. Espeilly, we would like to dedite our knowledgment of grtitude towrd the following signifint dvisors nd ontriutors: First nd foremost, we would like to thnk, Mrs M.Jothilkshmi, M.S., M.Phil., For her most support nd enourgement. She kindly red my pper nd offered invlule detiled dvies on grmmr, orgniztion, nd the theme of the pper, nd we would like to thnk, Mrs.C.Theeendr, M.s., nd M.Phil. To red my thesis nd to provide Vlule dvies. Seond we would like to thnk, Dr.S.Dhnlkshmi, MCA. M.Phil., Ph.D., M.E., to report of the pper, s well the other professors. Finlly, I sinerely thnk my prents, fmily, nd friends, who provide the dvie nd finnil support. The produt of this reserh pper would not e possile without ll of them. S. Y u v r t h i e t l Pge 47