On Tue, 2010-05-18 at 10:32 -0700, Joe Eykholt wrote:
> Joe Eykholt wrote:
> > Robert Love wrote:
> >> On Fri, 2010-05-07 at 16:26 -0700, Joe Eykholt wrote:
> >>> The following series implements the proposed-to-become-standard
> >>> FIP point-to-multipoint support.
> >>>  
> >>> The T11 FC-BB-6 committee is proposing a new FIP usage model called
> >>> VN_port to VN_port mode.  It allows VN_ports to discover each other
> >>> over a loss-free L2 Ethernet without any FCF or Fibre-channel fabric
> >>> services.  This is point-to-multipoint.  There is also a mode
> >>> of this called point-to-point (not implemented here) which provides
> >>> for making sure there is just one pair of ports operating over
> >>> the Ethernet fabric.
> >>>
> >>> The point-to-multipoint mode will work over direct links and
> >>> eventually, DCB switches.  Cisco switches require turning off
> >>> the FCoE feature to allow this, however.  One shouldn't take
> >>> this as an indication that switches will or will not more fully
> >>> support VN2VN mode.
> >>>
> >>> See the spec at http://www.t11.org/ftp/t11/pub/fc/bb-6/10-019v2.pdf
> >>> for more details.  That's close, but I know there are updates coming.
> >>>
> >>> This part of the BB-6 proposals may become more solid after the
> >>> next T11 meeting in June or the one after that.  The BB-6 standards
> >>> as a whole may not be ratified until April 2011 or so. 
> >>> I'd be interested to hear about whether these are useful enough
> >>> to integrate before the standard is completely done.
> >>>
> >>> Some of these patches are obviously applicable without the VN2VN
> >>> changes.
> >>>
> >>
> >> Hey Joe,
> >>
> >>     Can you help me understand where the fip->ctlr_src_addr gets updated
> >> after we have claimed a FCID? As far as I can tell we're setting it in
> >> fcoe_interface_setup and fcoe_interface_setup, but not anywhere around
> >> the time we call update_mac in the fcoe_ctlr_vn_timeout work thread.
> > 
> > ctl_src_addr never gets updated, it's always the native MAC address of the
> > interface.  When we get an FC_ID in VN2VN mode, we use update_mac to give
> > the address to fcoe, which it calls data_src_addr.
> > 
> >>     We're using the fip->ctlr_src_addr to send the CLAIM after 
> >> update_mac,
> >> but I'm not sure it's being updated.
> > 
> > That's correct.  The Claim comes from ctl_src_addr.  The contents show the
> > FC_ID and the MAC we're claiming, not the Ethernet header.
> 
> To add to this explanation, the MAC descriptor in the claim has the
> control MAC (what the spec calls ENode MAC), and the Vx_Port_ID descriptor
> has the FPMA data mac as inserted by this code:
> 
>          frame->vn.fd_desc.fip_dtype = FIP_DT_VN_ID;
>          frame->vn.fd_desc.fip_dlen = sizeof(frame->vn) / FIP_BPW;
>          hton24(frame->vn.fd_mac, FIP_VN_FC_MAP);
>          hton24(frame->vn.fd_mac + 3, fip->port_id);
>          hton24(frame->vn.fd_fc_id, fip->port_id);
> 
> I'll work on updating the patches to apply on top of the other recent patches.
> 

Thanks for the explanation Joe. I've reviewed all of these patches and
they look pretty good. Some can probably be consolidated, but I
appreciate you separating them for review.

I have two quips.

1) I'm a bit reluctant to have a 4th rport object (the fcoe_vn_port).
Would it make sense to add some private space at the end of the
fc_rport_priv so that the allocations aren't separate between libfc and
libfcoe's rports?

Is there ever a time when you'd have a VN2VN rport, but not a libfc
rport?

2) I think the fcoe_vn_port name might lead to some confusion. It sounds
like it's for NPIV. Also, it doesn't indicate that it's associated with
rports, i.e. that it's a "remote" entity. What about something like
fcoe_vn_rport or fcoe_vnvn_rport? (fcoe_vnvn_rport doesn't match your
naming convention though)

BTW: I'm fine with splitting out the libfcoe.c file into multiple files
if that helps.

Thanks, //Rob

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