Network Measurements

IP Network

Some Questions that are hard to answer about IP networks

Traffic Matrix Construction

Measurement Options

Traffic Matrix:
SNMP based methods

Traffic Matrix:
Flow based methods.

Traffic Matrix:
Method Comparison

Outline of the rest of the talk

IP Flow Abstraction

Collection System

Resources in the Measurement System

Measure/Export All Traffic Flows?

Flow Sampling?

Packet Sampling and Flow Sampling

Usage Estimation

Basic Ideas

Size independent flow sampling bad

Size dependent flow sampling

Statistical Properties

What is best choice of p(x)?

Optimal vs. size independent sampling

Charging and Sampling Error

Accuracy and Parameter Choice


Compensating variance for mean

Example: s=1

Example: s=2

How to reduce unbillable usage?

Tension between accuracy and volume