[openib-general] RDMA connection and address translation API

[Tom Tucker]

> -----Original Message-----
> From: Roland Dreier [mailto:rolandd at cisco.com] 
> Sent: Wednesday, August 24, 2005 11:04 AM
> To: Tom Tucker
> Cc: Roland Dreier; openib-general at openib.org
> Subject: Re: [openib-general] RDMA connection and address 
> translation API
> 
>     Tom> The listen side, however, I think needs a little tweaking. It
>     Tom> would be beneficial if the client can specify either an IP
>     Tom> address and port to listen on (effectively selecting a
>     Tom> particular device), or a wild card (all RDMA devices). An NFS
>     Tom> server is an example of the later. This is trivial to do by
>     Tom> providing an address to the listen call where a '0'
>     Tom> represents a wild card.
> 
> I agree that it's useful to be able to pass a sockaddr to 
> bind a listen to (just like the bind() call in userspace).  
> However, the problem is that in the IB world, an incoming 
> connection request does not come with a destination IP 
> address in any standard way.  So I don't know the right way 
> to implement bind() in the IB case.

I think I understand, but the purpose of specifying the IP address in
the listen is not to filter incoming connect requests, but rather to
determine which devices I listen on. I think this works for the IB case
as well. So the utility of the IP address specified in the listen is
only to determine which devices the sid is created on. Does this make
sense or am I missing something?

> 
> By the way, an IP address/port does not necessarily select a 
> single RDMA device.  It's a perfectly valid configuration to 
> have 10 network interfaces all with the same local IP address.
> 
>  - R.
> 
Yes, and in this case, all devices with the same IP address would end up
listening in the same way that specifying a wildcard (0) would result in
multiple devices listening.