Title: Performance Modeling of RuleBased Architectures as DiscreteTime Quasi BirthDeath Processes
1Performance Modeling of Rule-Based Architectures
as Discrete-Time Quasi Birth-Death Processes
- Authors
- Sándor Palugyai, Máté J. Csorba
- Ericsson Hungary, Test Competence Center
- http//ttcn.ericsson.se/
- E-mail sandor.palugyai, mate.csorba_at_ericsson.co
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2Motivation
- Rule-based architectures
- e.g. a firewall system in a router
- Design a mathematical model
- reproducability
- Predict performance parameters
- packet delay
- packet loss
- etc.
3Introduction
- Introduction to Rule-based architectures (Access
Control Lists) - Introduction of interfaces
- Markovian theory (QBDs)
- Our model (structure, mathematical background)
- Accuracy, results, future plans
4Rule-based architectures
- Access Control Lists
- Firewall systems
- Database applications
- Alternative behavior in software architectures
- TTCN-3 alt construction
- Switch Case
5Example Access Control Lists
- Network protection and admission control
mechanisms provided by Access Control Lists - Impact on performance based on linear execution
- Significant packet-delay and loss might appear
6ACLs applied
- Permit or deny network segments and individual
hosts - Sequential execution
- access-list 111 permit tcp any host 10.120.23.1
- access-list 111 deny any 10.120.23.0 0.0.0.255
7Introduction of interfaces
- Systems with a single processor and bus
- Interrupted packet processing
- Input may interrupt output packet handling too
8Quasi Birth-Death processes
- N(t) level process, J(t) phase process
- QBD ( one level up or down, or inside the actual
level ) - P transition probability matrix ( A matrices )
9Derivation of performance indices from the model
- Balance of the embedded chain
- Queue length distributions
- Delay !
- Packet loss !
- Output traffic of the Models
10Features of the Interface model
- Can model the delay caused by the input/output
interfaces (where queuing might appear) - modeling of Hardware elements
- Rules can be accept (fwd.) or deny (drop)
11QBD structure of the Interface model
12Matrix-structure of the Interface model
13Matrices of the Interface model
14Derivation of performance parameters
15Accuracy of the Interface model
16Properties of the Interface model
- The model of list-structures with interfaces
- Deduction of the Interface model
- Tool for evaluation of the model (parametrical)
- Simulations and measurements (ns-2)
- Applicable for other list topologies
17Future work
- Proofs of other conjectures
- Closing the gaps
- Model more hardware related structures
18- Thank You for Your Attention!
- E-mail sandor.palugyai, mate.csorba_at_ericsson.co
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