Locating network monitors: complexity, heuristics, and coverage

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# Locating network monitors: complexity, heuristics, and coverage - PowerPoint PPT Presentation

Locating network monitors: complexity, heuristics, and coverage. Kyoungwon Suh Yang Guo Jim Kurose Don Towsley. Motivation. Need to understand the performance of the network infrastructure. A monitor can achieve this goal. A monitor is placed inside a router

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### Locating network monitors: complexity, heuristics, and coverage

Kyoungwon Suh

Yang Guo

Jim Kurose

Don Towsley

Motivation
• Need to understand the performance of the network infrastructure.
• A monitor can achieve this goal.
• A monitor is placed inside a router
• A monitor can be deployed as a standalone measure box that taps into a communication link
• A monitor may capture or sample packets carried by this link
• In order to capture large fraction of the traffic, we may place multiple monitors on different links.
• Placing a monitor on a link incurs a deployment cost:
• Hardware/software cost
• Space cost
• Maintenance cost
• Each operation by the monitor also incurs some cost.
• Per-packet operating cost
• Placing the monitors on different position may have different benefits.
• The general goal will be maximizing the benefit while minimizing the cost.
Problem setting
• A flow: a collection of packets going through the same route on the network.
• D: a set of all flows.
• Si : the set of all flows carried by link i.
• yi: whether a monitor is deployed at link i.
• yi = 1: deployed.
• yi = 0: not deployed.
• fi: the cost of deploying a monitor on link i.
• The total deployment cost is:
• Operating cost:
• ci: the cost per-packet at link i.
• Depend on the volume of flows the monitor is monitoring
• j: the number of packets sent by flow j.
• mij: the fraction of flows sampled by the monitor on link i.
• The total operating cost:
Monitoring reward:
• The reward depends on which flow is monitored.
• The reward depends on what fraction of each flow is monitored
• If the monitor can capture every packet traversing the link,
• If the monitor only sample a fraction of each flow
Monitoring problems without sampling
• Each monitor collects all the packets of monitored flows,
• mij = 1 or 0 for all i, j.
• Budget Constrained Maximum Coverage problem (BCMCP)
• Total deployment cost is constrained.
• Maximize benefit
• Operating cost is ignored
• Minimum deployment cost problem (MDCP)
• A certain amount of monitoring reward should be guaranteed
• Minimize the deployment cost
• Operating cost is ignored
• Minimum deployment and operating cost problem (MDOCP)
• Minimize the sum of deployment and operating cost
Budget Constrained Maximum Coverage problem (BCMCP)
• Problem formulation
• The problem is NP-Complete, which can be shown by a reduction from a known NP-Complete problem, budgeted maximum coverage problem(MCP).
Budgeted maximum coverage problem (MCP)
• Definition:
• A collection of sets S = { S1, S2, …, Sm} with associated costs {c1, c2, …, cm} over a a domain of elements X = {x1, x2, …, xn}with associated weights {w1, w2, …, wn}
• Goal: find sets S’S such that total cost of elements in S’ does not exceed a given budget L and the total weight of elements covered by S’ is maximized.
• This problem is known to be NP-Complete
• Find some approximation algorithm
• Performance of an approximation algorithm A.
• A is said to achieve approximation ratio  if the weight generated by A is at least ( * optimal)