iWARP emulation protocol (was: [openib-general] RDMA connection andaddress translation API)

[Sean Hefty]

Kanevsky, Arkady wrote:
> CM passes IB addresses of both src and dest in REQ.
> How locally dest IP address is mapped to dest IB GID|LID is
> defined by IPoIB.
> We can request IBTA to define it also.
> But the goal is to define a protocol part in IBTA. 

The mapping from an IP address to a GID is controlled by a system administrator. 
  ARP can be used to resolve the IP address to the GID, but there still needs to 
be a way to map the TCP port number to a service ID, which goes across the wire, 
and needs to be defined.  Right now, the service ID is the only indicator that a 
CM or other recipient has that the private data has a particular format.

An alternative is to grab a reserved bit from the CM REQ to indicate that this 
header is present, and ignore the service ID in such cases (provided the 
destination TCP/IP address is given in the private data).

> You are correct that if rely on CM storing the IP address of the dest
> it is not needed to be passed back in REP.
> If we do not need to know that response came from a different IP
> address.
> Or a different port.

Why would you want to establish a connection using an address that's different 
from that specified by the requester?

- Sean