Routing In Multiprotocol Layered System Computer Science Essay

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Abstract- The provision of quality of service is the still objective of the world wide research. In recent times the demanding need of users is Qos. Quality of services play in important role to achieve high quality communication as TE perform vital role in providing Qos. As the result of MPLS network performance, restoration, load balancing and bandwidth optimization are optimized. Some algorithms deals with multimedia traffic, path selection and load balancing. In this paper we analyze the literature on routing in MPLS. Then we have provided a critical analyses of literature. We have made comparision among the advantages and disadvantages of those routing mechanisms and routing algorithms.

Key words: TE,Qos,MPLS

Introduction

Routing in MPLS is carried out by using different mechanisms such as Hybrid routing mechanism, traffic engineering mechanism, constraint based routing mechanism, routing through active measurements etc. These all mechanisms have played a vital role in providing the Qos. The Qos is the most demanding desire of the users. In HRM [1] most of the traffic is sent through MPLS while the remaining is sent through conventional IP routing. In HRM [1] tunnels are used to avoid congestion. The TE [4] mechanism is used for load balancing and to increased the through put and performance of the network. The purpose of the MPLS TE is to set up paths between the edge nodes. It directs traffic from one node to another node. The constraint based routing is used for restoration purposes and to avoid the loss of packets. These all mechanisms are used in MPLS to provide Qos to users. In this paper we will review the literature and find out the Pros and Cons of each mechanism. In section II we will highlight the problems of previous protocols.

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background study

In past few years the quality of service was not an emerging need of people. Qos was ignored in past. As long as internet is populated more and more in the world , multimedia files were created. The conventional IP network become over loaded. Their speed was very slow. Due to the multimedia files the traffic and congestion on the links is increased. As a result of congestion network became very slow. In mid 90s ATM was developed to solved this problem but ATM has a scaleability problem and could not meet the desires of users. To overcome the congestion and to balance the load on the network MPLS is designed. MPLS has provide a high speed backbone frame work. It has added many features in conventional IP routing such as bandwidth optimization, restoration,multiple path selection and to avoid the loss of packet through restoration. In MPLS tunnels are used to set up connection directly between the end nodes.

literature riview

In this paper Huan Phan etal [1] proposed a routing method for traffic management and congestion control mechanism. The writer has described the hybrid routing method. In HRM mostly traffic streams between source and destination are sent through MPLS while others are send through conventional IP routing. In HRM, MPLS tunnels are used to avoid the potential congestion that a created by the simple IP routing. In this method the traffic engineering is classified into two categories such as the local tunnels and end to end tunnels approach. The writer has proposed the greedy algorithm to identify the best traffic. The constraint based routing is used the route the traffic via single or multiple path. The write has also describe the traffic engineering tools that is applied at the AT & T internet backbone. In this paper problems with previous protocols has been discussed such as in OSPF protocol. The shortest paths are calculated through matrices and the routes could be changed through the changing the matrices. In HRM traffic is normally routed via shortest path where as MPLS is used as an orbitrary splitter.

Such mechanism is used in HRM which describes where to place tunnels and how to place tunnels.

The strengths of Huan Phan etal [1] are :

Real time traffic handling.

Improvement in overall network performance.

Quicker response of network failure in local tunnels approach.

Each tunnels is used to serve one traffic which stops the back flow problems.

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The limitations of Huan Phan etal [1] are :

Placement of tunnels problems such as how to place tunnels.

Constraint based routing.

HRM routes are limited numbers of flows.

A.Iselet etal [2] describes the problems of fast resilience due to growing need of the use of internet. The author has describe the previous routing protocols such as IP protocols that is too slow that it cannot fulfill the growing needs of the people. Iselet etal [2] has proposed a new approach that combines to protocols readily available on each router which is called ECMP (equal cost multiple path) extensions of OSPF. Islet etal has described this approach to increased the re-routing performance. The approaches that are used are the reduction of the timer. ECMP imporves the re-routing performance. ECMP of OSPF allows to send packet on several out going paths as for as there exit some shortest path. When the rourter detects that a link is not working properly. It will stop to send the packets to the remaining links. By using properly ECMP and MPLS we are able to provide very high network resilience with very short configural intervals. ECMP extension of OSPF provides a better load distributaion. The router sends a "Hello" message to all available links. If a link does not receive this message and response the router it will again and again send when a link will not consider this message that will be considerd as down link. The ECMP provides a fast local reaction to failures and this response time is in milliseconds.

ECMP is a best mechanism to avoid failures because it gives a fast failure reaction.

The strong points of Iselet etal [2] are :

Better load distribution.

Fast failure reaction.

Avoid the problems of missequencing of packets.

The weak points of Iselet etal [2] are:

Infrastructure is quiet limited.

Main problem on last hop for ECMP to establish tunnels.

Tricha Angali etal [3] has proposed an algorithm for quality of service routing. Many algorithm have been designed but none of them is that which provide the Qos. Qos is the demanding need are the users. The algorithm are obtained from Dijkistra algorithm. In MPLS network the focus is on the routing of LSP's on the network and many schemes of used. Such as minimum interference routing algorithm and profile based routing. This paper Qos

Algorithm it described for traffic flows in MPLS networks. This algorithm uses heuristic techniques. The algorithm consider multiple matrices and is scaleable. The algorithm is used for traffic flow management. While MPLS networks is managed by traffic engineering automated manager. (TEAM). The TEAM managed traffic on differenciated servers. The cost minimization is kept into account to select a matrices. This algorithm keeps into account available capacity,delay incurred numbers of LSP's in paths. The inverse function is choosen for available band width cost. This algorithm is desingen to achieve a balance between maximizing available band width and minimizing the number of hops and delay.

Such an algorithm is developed which manages traffic on the differentiated servers also because it is difficult task for TEAM.

The strength of Tricha Angali etal [3] are:

LSP's choose different paths and distributes the load in the networks.

Better band width utilization.

Best path selection.

Weaknesses of Tricha Angali etal [3] are:

Difficult to find paths.

Time consuming mechanism to find paths.

Haris Hodzic etal [4] has prososed a method for better band width utilization and to increase the through put of the network. The purpose of MPLS TE is to set up the paths between the edge nodes. To fulfill the traffic demand. The MPLS TE steers traffic to facilitate the use of available band width. The component required for a TE are : Topology distribution in formation, path information that is computing the reachability among the nodes. Directly traffic along the particular paths is carried out by TE. In tradition IP the packets of forwarded the on distination bases where the route look up process is performed by a router from source to destination. The sub optimal use of band width occurs. TE steer traffic to follow up path to a sub optimal path. It also avoid the packet drops. The constraint based routing is used in MPLS TE. By using the CBR the function of IP network is extended. The CBR placed an important role in tunnels definition. The constrained SPF is used to define paths from source to destination which take into account factors such as band width, policies and topologies. RSVP and LDP are also used with TE to reserve resources. The CBR is used to find a longer but light loaded paths.

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A mechanism is used to analyze the over loaded situation and avoid the packet drops.

Strength a Haris Hodzic etal [4] are:

Real time traffic handling.

Efficient use of band width.

Maximizing the through put of a network.

Less load path selection.

Weaknesses of Haris Hodzic etal [4] are:

Large amount of traffic load may cause packet drop.

Over load situation are not analyze.

Rahul Mishra etal [5] has proposed a active measurement approach to provide the quality of service.Routing in MPLS networks.He has described that when a new request comes a problem occurs in selecting LSP,S which can satisfy the Qos routing.When a setup is made the routes of an MPLS are fixed.From several LSP,s the routes are choosen.These routes depends upon the forward equivalence class of flow(FEC).FEC are selected according to the level of Qos and end to end addresses.MPLS adds many extra features in IP networks such a prespecified path for a flow which remains fixed until the failure of a node occurs. According to the Qos requirement,the pairs of egress and ingress LSRS are used and various LSP,s are formed.When a new request comes the decisions are made which LSP,s is selected according to the Qos requirement.There are many LSP,s available and some has More bandwidths than others even though a subset of an Lsp may bitterly satisfy the Qos requirement.To choose the LSP,s ,the writer has proposed a probing stream method. A low traffic stream is sent along the each LSP,s to egress LSR and end to enddelays are measured.From these end to end delays one can find the better LSP,s that satisfies the Qos.Throughput delays and packet size are estimated in probing stream method by using different mathematical laws.

Such a method is used which can work in a high speed network and that can keep ttack of varying traffic.

Rahul Mishras etal[5] strength are:

Better LSP,s selection to provide Qos.

Better bandwidth utilization of LSP,s.

Rahul Mishra etal[5] weaknesses are:

Probing stream method is not suitable for fast speed networks.

Does not keep track of varying traffic.

In this paper Xiao yu etal [6]has proposed an integrated design of multiple paths in MPLS.Multipath scheme provide a fault tolerant Qos mechanisim.The multiple path scheme checks for link failure and avoid the loss of traffic.Today in the internet network reliability and survivability are the main issues.Path protection mechanism is used to provide reliability and survivability.Two methods are used for path protection1:1 and 1:N.1:1 is used for single path routing protection whereas other is used for multiple protection scheme.ECMP is used to find the shortest path criteria.When a failure in a network is detected a backup path is used as an alternative.The purpose of the multipath routing is to maximize the network resources and failure survivability.Two bandwidth allocations techniques are used .PBAP is used as a path protection scheme and to select a backup path in case of failure.PBAR is used for restoration purposes.BARUR is used to decrease the usage of bandwidth while BAMMLUR is used to minimize the max of links utilization.

BAMMLUR is the best policy to balance the load and for the efficient utilization of the link.

Strengths of Xiao yu etal[6] are:

Better failure survivability.

Better load balancing.

Higher network resource utilization.

Weaknesses of Xiao yu etal[6] are:

Very difficult to find backup paths.

Time consuming mechanisim to calculate disjoint paths and active paths.

Krzy Szt of walkowiak etak[7] has proposed a approach called two route adjacent flow.This technique improves the performance of a network. In two route adjacent flow two paths are required one is active path and other is linked disjoint backup path.Adjacent two route flow also guarantees that a LSP is restored when a failure occurs. In two route adjacent flow different algorithms are used such as minimum hop algorithm(MHA),minimum interference routing algorithm(MIRA),Constraint shortest path first. These algorithms are used to establish a single path and these algorithms does not give information about network survivability. In adjacent -2 route flow MIRR algorithm is used and it establish two paths: active paths and backup paths. Shortest paths and disjoint paths are found through this algorithm.Adjacent-2 route flow approach is used for survivability of loss of packets.

MIRR algorithm is best to avoid the loss of packets. It calculates two paths and through backup paths LSP,s are restored.

The strengths of Krzy Szt of walko wiak etal[7] are:

Increase the performance of a network.

Decrease the chances of loss of packets.

Weaknesses of Krzy Szt of walko wiak etal[7] are:

Not too much quality of service is assured.

Finding path is time consuming and difficult task.

In this paper Haris Hodzic etal[8] has described the mechanisim of traffic engineering algorithms used in TE Mechanisim of MPLS.TE plays a vital role in congestion control mechanism and load balancing.It also improves the overall performance of the network.Qos is the powerful demand now a days.But as long as multimedia files are used traffic increases on the network which is a great problem and this problem is handled by traffic engineering.Writer has also discussed constraint based routing two paths are used such as active pathsanddisjoint paths.These decreases the loss of packets through restoration.In TE different algorithms are used such as CSPF,WSP,SWP,CSPFHOPcount,DAMOTE,DORA,PBR,MATE. and BCRA.These algorithms performs different functions to provide Qos routing.CSPFHOPcount find paths with minimum links.DAMOTE is used to compute LSP,s Dora is used for computing constraint routes.The function of the PBR is to provide a structure for dynamic routing.Mate function is to balance the load.

DAMOTE is a sophisticated algorithm to compute LSP,s .It keeps into account the bandwidth constraint.

Strengths of Horis Hodzic etal[8]are:

Improvements in network performance.

Better load balancing

Real time traffic handling.

Better LSP,s selections

Weaknesses of Horis Hodzic etal[8]are:

Complexity of algorithms.

CRITICAL ANALYSIS

Author [1] proposed a routing method for traffic management and congestion control mechanism. The writer has described the hybrid routing method. In HRM mostly traffic streams between source and destination are sent through MPLS while others are send through conventional IP routing. In HRM, MPLS tunnels are used to avoid the potential congestion that a created by the simple IP routing. In this method the traffic engineering is classified into two categories such as the local tunnels and end to end tunnels approach. The writer has proposed the greedy algorithm to identify the best traffic. The constraint based routing is used the route the traffic via single or multiple path. The write has also describe the traffic engineering tools that is applied at the AT & T internet backbone. In this paper problems with previous protocols has been discussed such as in OSPF protocol. The shortest paths are calculated through matrices and the routes could be changed through the changing the matrices. In HRM traffic is normally routed via shortest path where as MPLS is used as an orbitrary splitter.A.Iselet etal [2] describes the problems of fast resilience due to growing need of the use of internet. The author has describe the previous routing protocols such as IP protocols that is too slow that it cannot fulfill the growing needs of the people. Iselet etal [2] has proposed a new approach that combines to protocols readily available on each router which is called ECMP (equal cost multiple path) extensions of OSPF. Islet etal has described this approach to increased the re-routing performance. The approaches that are used are the reduction of the timer. ECMP imporves the re-routing performance. ECMP of OSPF allows to send packet on several out going paths as for as there exit some shortest path. When the rourter detects that a link is not working properly. It will stop to send the packets to the remaining links. By using properly ECMP and MPLS we are able to provide very high network resilience with very short configural intervals. ECMP extension of OSPF provides a better load distributaion. The router sends a "Hello" message to all available links. If a link does not receive this message and response the router it will again and again send when a link will not consider this message that will be considerd as down link. The ECMP provides a fast local reaction to failures and this response time is in milliseconds. Tricha Angali etal [3] has proposed an algorithm for quality of service routing. Many algorithm have been designed but none of them is that which provide the Qos. Qos is the demanding need are the users. The algorithm are obtained from Dijkistra algorithm. In MPLS network the focus is on the routing of LSP's on the network and many schemes of used. Such as minimum interference routing algorithm and profile based routing. This paper Qos

Algorithm it described for traffic flows in MPLS networks. This algorithm uses heuristic techniques. The algorithm consider multiple matrices and is scaleable. The algorithm is used for traffic flow management. While MPLS networks is managed by traffic engineering automated manager. (TEAM). The TEAM managed traffic on differenciated servers. The cost minimization is kept into account to select a matrices. This algorithm keeps into account available capacity,delay incurred numbers of LSP's in paths. The inverse function is choosen for available band width cost. This algorithm is desingen to achieve a balance between maximizing available band width and minimizing the number of hops and delay. Haris Hodzic etal [4] has prososed a method for better band width utilization and to increase the through put of the network. The purpose of MPLS TE is to set up the paths between the edge nodes. To fulfill the traffic demand. The MPLS TE steers traffic to facilitate the use of available band width. The component required for a TE are : Topology distribution in formation, path information that is computing the reachability among the nodes. Directly traffic along the particular paths is carried out by TE. TE steer traffic to follow up path to a sub optimal path. It also avoid the packet drops. The constraint based routing is used in MPLS TE. By using the CBR the function of IP network is extended. The CBR placed an important role in tunnels definition. The constrained SPF is used to define paths from source to destination which take into account factors such as band width, policies and topologies. RSVP and LDP are also used with TE to reserve resources.Rahul Mishra etal [5] has proposed a active measurement approach to provide the quality of service.Routing in MPLS networks.He has described that when a new request comes a problem occurs in selecting LSP,S which can satisfy the Qos routing.When a setup is made the routes of an MPLS are fixed.From several LSP,s the routes are choosen.These routes depends upon the forward equivalence class of flow(FEC).FEC are selected according to the level of Qos and end to end addresses.MPLS adds many extra features in IP networks such a prespecified path for a flow which remains fixed until the failure of a node occurs.Xiao yu etal [6]has proposed an integrated design of multiple paths in MPLS.Multipath scheme provide a fault tolerant Qos mechanisim.The multiple path scheme checks for link failure and avoid the loss of traffic.Today in the internet network reliability and survivability are the main issues.Path protection mechanism is used to provide reliability and survivability.Two methods are used for path protection1:1 and 1:N.1:1 is used for single path routing protection whereas other is used for multiple protection scheme.ECMP is used to find the shortest path criteria.When a failure in a network is detected a backup path is used as an alternative.The purpose of the multipath routing is to maximize the network resources and failure survivability.Two bandwidth allocations techniques are used .PBAP is used as a path protection scheme and to select a backup path in case of failure.PBAR is used for restoration purposes.BARUR is used to decrease the usage of bandwidth while BAMMLUR is used to minimize the max of links utilization.Krzy Szt of walkowiak etak[7] has proposed a approach called two route adjacent flow.This technique improves the performance of a network. In two route adjacent flow two paths are required one is active path and other is linked disjoint backup path.Adjacent two route flow also guarantees that a LSP is restored when a failure occurs. In two route adjacent flow different algorithms are used such as minimum hop algorithm(MHA),minimum interference routing algorithm(MIRA),Constraint shortest path first. These algorithms are used to establish a single path and these algorithms does not give information about network survivability. In adjacent -2 route flow MIRR algorithm is used and it establish two paths: active paths and backup paths. Haris Hodzic etal[8] has described the mechanisim of traffic engineering algorithms used in TE Mechanisim of MPLS.TE plays a vital role in congestion control mechanism and load balancing.It also improves the overall performance of the network.Qos is the powerful demand now a days.But as long as multimedia files are used traffic increases on the network which is a great problem and this problem is handled by traffic engineering.Writer has also discussed constraint based routing two paths are used such as active pathsanddisjoint paths.These decreases the loss of packets through restoration.In TE different algorithms are used such as CSPF,WSP,SWP,CSPFHOPcount,DAMOTE,DORA,PBR,MATE. and BCRA.These algorithms performs different functions to provide Qos routing.CSPFHOPcount find paths with minimum links.DAMOTE is used to compute LSP,s Dora is used for computing constraint routes.The function of the PBR is to provide a structure for dynamic routing.Mate function is to balance the load.

v. CONCLUSION AND FUTURE WORK

In this paper we have discuss and summarized then analyzed the strength and weaknesses of several techniques of routing in MPLS in literature view we found that quality of service is the most demanding desired of a user on the network. Most imperative techniques after critical literature view provided in this paper. In future we may proceed with the development of a frame work. We satisfies the real time traffic handling and quality of service issue and MPLS in future. Accordingly this work guides the future researcher to work on the MPLS quality of service routing. We have a lot of ideas and innovations in routing techniques in MPLS based on review literature.