[ofa-general] Open Fabrics iWARP Driver for Chesio T3 card

[Steve Wise]

SEGERS Koen wrote:
> What is the benefit of using the iWARP driver? Do you offload the 
> traffic comming from the cluster directly to the chelsio card (RDMA 
> directly to Chelsio)?
>  

iWARP is a suite of standard protocols that implement RDMA over a TCP or 
SCTP connection.  The  devices that support iWARP usually implement all 
of these protocols (including TCP/IP/ethernet) in hardware.  The device 
drivers for these devices plug into the Linux/OFA RDMA core and support 
the Linux/OFA RDMA verbs which are mostly common between both IB and iWARP.

So think of it as an RDMA transport that uses standard Ethernet and IP 
technology.  There is no wire-level interoperability between IB and 
iWARP: They are different L1-L4 protocol stacks below the RDMA API.  But 
_above_ the RDMA API, you can have a single application use the Linux 
RDMA Verbs interface and deploy that same application over both IB 
networks and IW networks.

Application/Middle-ware examples include MPI, iSCSI/iSER, and NFS-RDMA.

> Would it be beneficial to have the iWARP driver installed on nodes that 
> communicate with clients over IP and with other servers (of its cluster) 
> over IB? We are now using SDP as an intercluster protocol, but in the 
> future we are probably going to VERBS for it.
>  

I'm not sure how you would utilize it in your setup.  But I don't 
understand your cluster architecture to say for sure whether it might 
help you or not.

You might contact the iWARP providers directly to help understand if 
their solutions can help you.  Also, there are other technologies that 
these devices typically support that might be helpful for you.

> Can we read the documentation on a website somewhere?
>  

The iWARP Protocols are IETF IDs and RFCs that can be found at

http://www.ietf.org/html.charters/rddp-charter.html

There is other information on RDMA over TCP/IP at

http://www.rdmaconsortium.org/home

Hope this helps.

Steve.