Narayan Desai wrote:
Sanjai, does your software deal with bugs in BGP or OSPF implementations and
the like?
No, we don't detect implementation bugs, just bugs in configuration.
The reason this approach works for network management is that there are a
relatively small number of models that are needed, whereas on a unix system
there may be hundreds of models that would need to interact with one another.
(to handle everything from minicom, to the kernel, to dns and dhcp, sendmail,
postfix, etc)
The key simplifying observation is that there is a set of fundamental
protocols/distributed algorithms (P/DA) whose compositions make up an
end-to-end system. DNS, DHCP, SENDMAIL are all examples of these. We
capture the answer to the question "what does it mean for a group of
agents executing a particular P/DA to be correctly configured?" This
becomes a model of the configuration logic for that P/DA. We now compose
these models to create a validation for the whole system. This was the
idea behind the Service Grammar work in which the compositions are
programmed in Prolog, not full first-order logic. See the papers Using
Service Grammar to Diagnose Configuration Errors in BGP-4.
<http://www.argreenhouse.com/papers/narain/scp-BGP.pdf> /Proceedings of
USENIX LISA Conference, /San Diego, CA, 2003, and Building Autonomic
Systems via Configuration.
<http://www.argreenhouse.com/papers/narain/Autonomic.pdf> /Proceedings
of AMS Autonomic Computing Workshop, /Seattle, WA, 2003.
Behavioral tests aren't as powerful as the analytical ones that Sanjai does, but they sure are a lot more incremental.
An example of where behavioral tests don't seem appropriate is in testing single points of failure. We cannot fail individual components and links to see whether end-to-end service hold up, can we? An analytic approach is needed. However, this is also not an either/or situation. Behavioral and analytic tests are complementary.
-- Sanjai
------------
Sanjai Narain, Ph.D.
Senior Research Scientist
Information Assurance and Security Department
Telcordia Technologies, Inc.
1 Telcordia Drive, Room 1N-375
Piscataway, NJ 08854
732 699 2806 (T)
908 337 3636 (M)
[EMAIL PROTECTED]
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