Ashish Gupta Under Guidance of Prof. B.N. Jain Department of Computer Science and Engineering Advanced Networking Laboratory

Overview Current routing in the Network Why MPLS ? Like ATM over IP The need for fault tolerance today What is the problem with current Path Protection Schemes : Give no assurance for QoS The challenge : give us QoS guarantees but don’t use too much bw What we have proposed – SBPP The need for algorithms for various QoS constraints Present the algorithms in a simple manner – only the switch over time and end to end delay Mention other work done : how we finally solved the reliability problem We have made a Admission Control simulator in C++… the algo performs really well ! : Gives you tradeoffs now for various QoS Constraints The visualization of our Algorithms The need and its features, and the demo Conclusion : no worries on failure now Over all work done (besides the algos), we have also written a paper to be send to ICCC Any questions ?

IP

IP

BACKUP PATH

Should provide quick recovery after a failure Optimal Use of Backup Resources

Backup Path Primary Path

The solutions are fixed No assurance for various QoS constraints We need guarantees that in case of failure, we will not lose packets for more than 50 ms Or even in case of failure, the end to end delay will not exceed 150 ms

 Results in fewer backup paths – conserves resources  Can meet QoS constraints in a “tight” manner  Gives flexibility – How ? The Main Idea Look at the path as a sequence of segments and protect each segment separately

How to divide the path into segments such that ? If any segment fails, specified QoS constraints can be guaranteed A Segment is a set of nodes which consists of: 1.Segment Switch Router – protects the segment 2.Protected Nodes Main Focus

Various QoS constraints considered: –Bounded Switch-Over Time –End-to-End Delay –Jitter –Reliability –Combination of above Algorithms have to use backup resources effectively

Switch over time : The time for which the packets are lost between the failure and recovery

Using Timing Analysis, we derived a limit to the possible segment size RTT( R i, R j ) + T test < 

Divide the path into minimum number of segments such that the inequality is satisfied for each segment  Intuitive choice: Greedy Algorithm  Problems with Greedy Algorithm  A new Adaptive Algorithm for Bounded Switch over time has been developed  Takes into account the topology and bandwidth reservation in the network

 Assures QoS satisfaction  Proved to be optimal  Robust  We have implemented it using the LSP Admission Control Simulator and tested it  Results indicate its efficiency

An important parameter in multimedia communications

In this analysis, we need to consider backup paths also. Max (T + ( T 2 – T 1 ) ) < 

We need to satisfy the inequality for each possible path For each segment (found using previous algorithm), find the shortest possible backup path Will give the minimum value of end-to-end delay Check if inequality is satisfied, otherwise reject the current segment

 Jitter – similar to End-to-End delay  Multiple QoS constraints  Bounded Switch Over time  End-to-End Delay  Jitter Developed an algorithm using Dynamic Programming Approach

 Finding Reliability between two nodes : An NP complete problem  Earlier we were engaged in finding bounds  But turns out, Segment Based Approach allows for simpler analysis !

An O(No. of Links + (No. of Segments) 2 ) Algorithm to find exact path reliability ! Algorithm for finding the most reliable backup path A heuristic Algorithm has been developed for meeting bounds on Reliability for the protection configuration

Probability of Primary path for a particular segment S i to be working Probability of Backup path for Segment S i to be working Probability of S i to S j-1 segments’s primary path to be working & segment S j primary path to have an error

 A visualization system developed for the Segment based Algorithms: based on POLKA  Closely Integrated with LSP Admission Control Simulator  Visualizations are Dynamic not Static  Aids in understanding how the algorithms work  Assists in establishing correctness of algorithms and simulations

Topology Used

Aim of the Experiments To evaluate the resource related advantages of Segment based Approach, while assuring QoS constraints

 An LSP Admission Control Simulator has been developed in C++  Simulates multiple networks with different reservation policies and compares results  We implement the Segment Based Algorithm for Bounded Switch over time for providing Protection to LSPs generated  BW Sharing Mechanisms also implemented

Simulation Setup  Topology with 50 routers and 82 links  LSPs setup using Djiktra’s Algorithm  BW of each link: 3000 to units  Delay of each link : 8 to 12 ms  BW requirements of each LSP : 20 to 70 units LSP requests were generated with different QoS parameters

 Today major networking companies are quickly shifting towards MPLS-based networks  Major Players: Cisco, AT&T, Level 3, Hewlett Packard, UUNet, MCI World Com  “Within an MPLS-enabled network, even packet voice services such as voice over IP will benefit from reduced latency and congestion control” Ranjeet Sudan, MPLS product manager at Cisco Efficient Fault Tolerance in such services is a major concern

For providing reliability to such services we now have Fault Tolerance Schemes which: 1.Guarantee satisfaction of various QoS constraints in case of failure 2.Use backup resources in an optimal manner

 Mechanisms for Detection and Notification  Algorithms for various QoS constraints  Bounded Switch over time  End-to-End delay  Jitter  Combination of above  Reliability  Issues relating to backup path – Sharing…  Admission Control Simulator developed for above  Visualization System

Paper being submitted to Being held in Mumbai this year