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Locating network monitors: complexity, heuristics, and coveragePowerPoint Presentation

Locating network monitors: complexity, heuristics, and coverage

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

Kyoungwon Suh

Yang Guo

Jim Kurose

Don Towsley

Motivation coverage

- 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.

- Several things we need to consider when deploying the monitors.
- 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.

- Placing a monitor on a link incurs a deployment cost:
- The general goal will be maximizing the benefit while minimizing the cost.

Problem setting monitors.

- 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.

- Deployment monitors. cost: deployment cost may be different from link to link.
- fi: the cost of deploying a monitor on link i.
- The total deployment cost is:

- Operating cost:
- Depend on the link speed, specific to the link,
- 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:

- Depend on the link speed, specific to the link,

- Monitoring reward monitors.:
- 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 monitors.

- 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 monitors. (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) monitors.

- 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)

- Performance of an approximation algorithm A.

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