[ofa-general] Re: tcp/rdma port unification - iscsi/ddp/toe vs iwarp/ddp/toe

[Or Gerlitz]

Steve Wise wrote:
> Depends on the 4-tuple. The demux done in the TOE hw uses src addr/port and dst addr/port.  

Hi Steve, 

Trying to better understand the problem and possible solutions, I looked on the Chelsio iscsi offload driver (drivers/scsi/cxgb3i/* & Documentation/scsi/cxgb3i.txt) - which basically should suffer from the same issue - how to distinguish between a iscsi/os-tcp connection to iscsi/hw-tcp (toe) connection (or to iperf connection, etc as we discussed). 

I saw it manages the source port from its own data-structure (similar to the rdma-cm) but it doesn't  open of a socket / nor bind the port - so I assume that a host opens two iscsi/tcp connections to a target on the same src ip/port - a party starts... At this point I came a cross the "cxgb3: manage private iSCSI IP address" patch whose change log states that its mostly ARP related- is the ARP resolution for iSCSI/DDP/TOE different from iWARP/DDP/TOE? does the below patch/approach eliminates the port space problem for iscsi/ddp?

Or.

commit a109a5b916bc180e14fad0d1e9c37a08c85652c0
Author: Karen Xie <kxie at chelsio.com>
Date:   Thu Dec 18 22:56:20 2008 -0800

    cxgb3: manage private iSCSI IP address

    The accelerated iSCSI traffic could use a private IP address unknown to the OS:
    - The IP address is required in both drivers to manage ARP requests and connection set up.
    - Added an control call to retrieve the ip address.
    - Reply to ARP requests dedicated to the private IP address.

    Signed-off-by: Divy Le Ray <divy at chelsio.com>
    Signed-off-by: Karen Xie <kxie at chelsio.com>
    Signed-off-by: David S. Miller <davem at davemloft.net>