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error-codes.md

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Error Codes

TWAMP error codes as defined in RFC 4656 (OWAMP) and used in RFC 5357 (TWAMP).

Error Code Reference

Code Name Description
0 OK Success - No error occurred
1 Failure Failure, reason unspecified (catch-all)
2 Internal Error Internal error occurred in the implementation
3 Not Supported Some aspect of the request is not supported
4 Permanent Resource Limitation Cannot perform request due to permanent resource limitations
5 Temporary Resource Limitation Cannot perform request due to temporary resource limitations

Error Code Details

Code 0: OK

Meaning: The operation completed successfully.

Action: None required. This indicates normal operation.

Example scenarios:

  • Connection established successfully
  • Test session started successfully
  • All packets transmitted and received

Code 1: Failure (Unspecified)

Meaning: A general failure occurred, but the specific reason is not identified or does not fit other categories.

Possible causes:

  • Network connectivity issues
  • Unexpected protocol violations
  • General communication errors

Troubleshooting:

  1. Check network connectivity between endpoints
  2. Verify firewall rules allow TWAMP traffic
  3. Check logs for specific error messages
  4. Verify both endpoints are using compatible TWAMP versions

Code 2: Internal Error

Meaning: An internal error occurred within the TWAMP implementation.

Possible causes:

  • Software bug
  • Memory allocation failure
  • System resource exhaustion
  • Unexpected exception

Troubleshooting:

  1. Check system logs for errors
  2. Verify sufficient system resources (memory, CPU)
  3. Try restarting the TWAMP process
  4. Report bug if reproducible

Code 3: Not Supported

Meaning: The requested feature or parameter is not supported by this implementation.

Possible causes:

  • Requesting authenticated mode (not implemented in twampy)
  • Requesting encrypted mode (not implemented)
  • Using unsupported protocol features
  • Incompatible protocol version

Troubleshooting:

  1. Verify you're using unauthenticated mode
  2. Check that both endpoints support the requested features
  3. Review RFC 5357 for optional vs required features
  4. Use compatible protocol parameters

twampy specific limitations:

  • Only unauthenticated mode is supported
  • Authenticated and encrypted modes return this error
  • Some RFC 5938 and RFC 6038 features not supported

Code 4: Permanent Resource Limitation

Meaning: The request cannot be performed due to permanent resource constraints.

Possible causes:

  • Maximum number of concurrent sessions reached
  • Insufficient port range available
  • Hardware limitations
  • License restrictions (commercial implementations)

Troubleshooting:

  1. Reduce number of concurrent sessions
  2. Check system configuration limits
  3. Verify no port conflicts exist
  4. Review system resource allocation

Code 5: Temporary Resource Limitation

Meaning: The request cannot be performed right now due to temporary resource constraints, but may succeed if retried later.

Possible causes:

  • Temporary memory shortage
  • CPU overload
  • Network buffer exhaustion
  • Rate limiting

Troubleshooting:

  1. Wait and retry the operation
  2. Reduce packet rate or session count
  3. Check system load (CPU, memory, network)
  4. Implement exponential backoff for retries

Error Handling Best Practices

For Users

  1. Check error code: Identify the specific error code returned
  2. Review logs: Enable verbose or debug logging for details
  3. Verify configuration: Ensure parameters are within supported ranges
  4. Test connectivity: Verify network path to remote endpoint
  5. Retry appropriately: For code 5, retry after a delay

For Developers

  1. Log error details: Include error code and context in logs
  2. Provide meaningful messages: Translate error codes to user-friendly text
  3. Implement retries: Automatically retry on code 5 errors
  4. Validate inputs: Check parameters before sending requests
  5. Handle gracefully: Don't crash on protocol errors

Example Error Scenarios

Scenario 1: Connection Refused

$ twampy controller 192.168.1.100
Error: Connection refused (Code 1)

Cause: No TWAMP server listening on the target

Solution:

# Verify server is running
netstat -ulnp | grep 862

# Start responder if needed
twampy responder :862

Scenario 2: Authenticated Mode Not Supported

$ twampy controller 192.168.1.100
Error: Authenticated mode not supported (Code 3)

Cause: Server requires authentication, but twampy only supports unauthenticated mode

Solution: Configure server for unauthenticated mode or use a different client

Scenario 3: Too Many Sessions

$ twampy controller 192.168.1.100
Error: Maximum sessions reached (Code 4)

Cause: Server has reached its session limit

Solution: Wait for existing sessions to complete or increase server session limit

Scenario 4: Temporary Overload

$ twampy sender 192.168.1.100
Error: Temporary resource limitation (Code 5)

Cause: Server is temporarily overloaded

Solution: Retry after a brief delay

Related References