Thursday, June 23, 2016

FAUCET troubleshooting/FAQ

This post documents some common troubleshooting steps for bringing up FAUCET.


How do I configure/where's the documentation for some FAUCET feature?

Look for configuration for that feature in the FAUCET unit tests (ie. read https://github.com/REANNZ/faucet/blob/master/tests/faucet_mininet_test.py and adapt a config file from that test's CONFIG attribute).


Where do I look for controller status?

By default, in /var/log/faucet/faucet.log. You should see messages as hosts are learned on VLANs, such as:

Jun 24 11:24:56 faucet DEBUG    Packet_in dp_id: eccd6df72de7 src:b8:ae:ed:73:20:90 in_port:1 vid:2003
Jun 24 11:24:56 faucet INFO     learned 5 hosts on vlan 2003

If you don't, something else is wrong - see below.


What does unknown DPID in the FAUCET log mean?

dp_id in configuration, and on the switch have to match. Make them the same. Unless they are, the switch won't come up. dp_id is a hex number.


FAUCET reports errors parsing my config file.

  • FAUCET uses YAML, which is sensitive to tabs versus spaces and correct indentation. Use spaces exclusively. Use the same configuration format as what the tests use (see above documentation FAQ).
  • Use quotes around strings (Eg, MAC addresses in ACLs)  to stop the YAML parser from misinterpreting them as numbers.


How I know the OpenFlow connection is up?

  • Check the FAUCET log (see above),
  • Check that the switch is configured to connect to port FAUCET is listening on.
  • Use standard networking troubleshooting to ensure that the switch can make a successful TCP connection to the controller (Eg, use wireshark to verify a TCP connection is attempted and completed and that OpenFlow messages are being exchanged without errors).
  • Check that FAUCET has provisioned flows on the switch - check that there flows installed in tables 0-4. If there are no flows or no flows other than in table 0, then your connection is not up (see above).

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