1. Architectural Implications of the “FixIt” KP Application
Jennifer Rexford
Internet and Networking Systems
AT&T Labs - Research; Florham Park, NJ

2. Example “FixIt” Application
User problem
User cannot reach
Asks the KP to fix the problem
Troubleshooting strategies
Launch test probes from other vantage points
Combine problem/success reports across users
Consider recent anomalies that might be related
Combine information from multiple domains

3. Probe From User’s Vantage Point
DNS directs user to different replica of Web site! ?
user
Works fine!
operator
Operator can’t see the problem without walking in the user’s shoes.

4. Combine Information Across Users
Cluster users to narrow down the root cause ?
Works fine!

5. Consider Recent Network Anomalies
Measurement and analysis
of routing messages
7081
7018
1239
Route “ ” to /8 withdrawn two
minutes ago, making address unreachable!

6. Combine Information From Multiple Domains
Typographical error causes prepending of “7018” in path.
Advertisement “ ”
automatically discarded as
part of BGP loop prevention
7081
AS 1239 notes suspicious
route “ ”
from AS 7081!
7018 ?
1239
Operator can notify AS 7081 to fix the problem!

7. Knowledge Plane Implications
Launch test probes from other vantage points
Send test traffic from the context of the end user
Log information about DNS server, Web IP address, etc.
Combine information across users
Consider host pairs (not) able to reach each other
Cluster the host pairs and look for commonalities
Consider recent anomalies
Continuously monitor and note possible anomalies
Preposition results of analysis for future reference
Combine information from multiple domains
Collect and analyze results at many locations
Combine information to troubleshoot problems