FreeBSD 10-stable (r274577) LACP / IEEE 802.3ad with TP-Link TL-SG2008 - not working

[John-Mark Gurney]

Alan Somers wrote this message on Thu, Dec 18, 2014 at 09:15 -0700:
> On Wed, Dec 17, 2014 at 10:11 PM, Craig Rodrigues <rodrigc at freebsd.org> wrote:
> > On Wed, Dec 17, 2014 at 9:08 PM, Craig Rodrigues <rodrigc at freebsd.org>
> > wrote:
> >>
> >>
> >>
> >> On Wed, Dec 17, 2014 at 5:36 PM, David P. Discher <dpd at dpdtech.com> wrote:
> >>>
> >>>
> >>> Yeah, Alan - will do ... if I decided to look into more.  That is why I was
> >>> looking for spec on LACP.  One side is doing it wrong.  FreeBSD is looking
> >>> for a LACPDU of exactly sizeof ( struct lacpdu ) which is 124 bytes. The
> >>> TP-Link is sending a PDU of 128 bytes. I was hoping someone would know off
> >>> hand what the spec says, if the PDU "should be" or "must be".
> >>>
> >>
> >>
> >> I think you have stumbled across a valid problem in the FreeBSD code.  I
> >> don't have access
> >> to 802.3ad-2000, but this might give you some clues:
> >> http://kb.juniper.net/InfoCenter/index?page=content&id=KB17674
> >>
> >> I would also look at the source code of wireshark to be sure.  wireshark
> >> has a sample capture of LACP packets here:
> >>
> >> http://wiki.wireshark.org/LinkAggregationControlProtocol
> >>
> >>
> > And here:
> >
> > http://www-01.ibm.com/support/docview.wss?uid=isg1VM64842
> 
> Good find, Craig.  Also, I found the full LACPDU definition.  It's in
> section 5.4.2.2, page 33, of the 802.1ax-2008 spec that I linked to.
> You can see the 4-byte FCS field at the end.  Does your tp_link[4]
> field look like an FCS?  If so, you need to figure out why it's
> propagating all the way up to the LACP level.

It very well could be that the authors of the TP-Link firmware missed
the comment in 1ax that says the FCS is generated by the MAC, and
include it in their sending...

If you could capture the original frame, and check the ether_type
field, to see if it is 124 or 128... If it's 128, they probably added
the FCS manually and the the MAC adds it a second time...

-- 
  John-Mark Gurney				Voice: +1 415 225 5579

     "All that I will do, has been done, All that I have, has not."