please handle OpenFlow error messages sensibly

[adferguson]

hi all,

I recently realized that NetCore silently ignores OpenFlow error messages (ie, ErrorMsg from ocaml-openflow) received from the switch. it appears that NetKat is the same.

at the very least, please log these messages, and honestly, during development, I would prefer to see the controller abort due to many types of errors (eg, OFPFMFC_ALL_TABLES_FULL or OFPFMFC_BAD_COMMAND) rather than silently pretending that the policy had been installed correctly.

handling the OpenFlow error messages sensibly greatly simplifies the task of debugging a policy which is not functioning correctly because of switch limitations.

thank you,
Andrew

[jnfoster]

Please ask Shriram to purchase a platinum NetKAT support plan :-)

Seriously: this is a great proposal. We will add it to our (deep) work
queue.

-N

On Wed, Dec 4, 2013 at 5:09 PM, Andrew Ferguson [email protected]:

hi all,

I recently realized that NetCore silently ignores OpenFlow error messages
(ie, ErrorMsg from ocaml-openflow) received from the switch. it appears
that NetKat is the same.

at the very least, please log these messages, and honestly, during
development, I would prefer to see the controller abort due to many types
of errors (eg, OFPFMFC_ALL_TABLES_FULL or OFPFMFC_BAD_COMMAND) rather than
silently pretending that the policy had been installed correctly.

handling the OpenFlow error messages sensibly greatly simplifies the task
of debugging a policy which is not functioning correctly because of switch
limitations.

thank you,
Andrew

—
Reply to this email directly or view it on GitHubhttps://github.com//issues/188
.

[adferguson]

lol. thanks Nate. :-)

our NetCore fork now has basic logging for these messages and some others, but I wanted to let y'all know for NetKAT.

[reitblatt]

Why did poor Carolyn get assigned to this? I'm all in favor of dumping boring work on interns, but after their internship is over?

[jnfoster]

Boom!

[reitblatt]

Ok, this should be against ocaml-openflow, not frenetic. Nominally, the frenetic runtime should be handling all this beneath the programmer's view, but ocaml-openflow doesn't even expose these errors. I'm closing this and re-opening in ocaml-openflow.

[adferguson]

hi Mark,

please reopen this issue -- while you are right that NetKAT's use of ocaml-openflow means that ocaml-openflow also needs to be better about handling and exposing errors when used with "SDN.ml", there is still a problem with NetKAT, as Controller.ml blissfully ignores any switch configuration or flow table update failures.

by contrast, NetCore does not have any trouble using the current version of ocaml-openflow since it does all of its own switch message handling in its Controller: https://github.com/adferguson/frenetic/blob/netcore/lib/NetCore_Controller.ml#L370

thank you,
Andrew

[arjunguha]

May we close this?

[mcanini]

I don't think was resolved :-(

[arjunguha]

ah yes you're right. Yeah, we should fix. hmmmm.

[craig-riecke]

This is done in Frenetic_OpenFlow_0x04, and so will get merged with the code for Issue #477.