get a destination LID

[SiTi]

Hello to everyone!
I encountered an obstacle and would like someone to help me with an
advice. I want to use InfiniBand via IB Verbs, but I don’t understand
how I can get Destination LID and other necessary information to set
up connection. All the examples that I’ve seen use sockets for the
exchange of this information as it explains «for simplicity».
I wonder if there is any way to configure Subnet Manager so that it
could use static settings? Or I can exchange this information only via
IB Verbs without using off-site protocols (TCP/IP, IPoIB, etc.)? And
in general, what can be done to solve this problem?

[Ali Ayoub]

Hi SiTi, see below:

On May 11, 10:54 pm, SiTi <SiTiComp...@yandex.ru> wrote:
> Hello to everyone!
> I encountered an obstacle and would like someone to help me with an
> advice. I want to use InfiniBand via IB Verbs, but I don’t understand
> how I can get Destination LID  and other necessary information to set
> up  connection. All the examples that I’ve seen use sockets for the
> exchange of this information as it explains «for simplicity».
> I wonder if there is any way to configure Subnet Manager so that it
> could use static settings?

Yes, you can provide the SM a configuration file with static LIDs.
Read the SM manual for more information.

> Or I can exchange this information only via
> IB Verbs without using off-site protocols (TCP/IP, IPoIB, etc.)?

> in general, what can be done to solve this problem?

Actually, this is not a problem.
For any unicast traffic you want to send, you need to know the address
of the destination beforehand; In TCP/IP sockets, usually you need the
destination IP/Port. In InfiniBand you need different type of address
(e.g. QPN/LID) and this information should be available to the sender
before he initiates the traffic.. so actually the requirement to know
the DLID in InfiniBand is normal (exactly like how you need the DIP in
TCP/IP).. But if you still want to use sockets-like API (to resolve
the IB address using sockets), then you must use IP based driver (over
InfiniBand) such as IPoIB and exchange the QP info over it, or you can
use RDMA-CM (communication manager) that provides you sockets based
API to manage RDMA/QP resources.

See RDMA-CM man page:
http://linux.die.net/man/7/rdma_cm

This is an Example by Roland Dreier:
http://digitalvampire.org/blog/index.php/2007/10/10/materials-from-linuxconfeu-rdma-tutorial-at-last/

[SiTi]

Thank you for informative reply.

> so actually the requirement to know the DLID in InfiniBand is normal
> (exactly like how you need the DIP in TCP/IP)..

I had thought before, that the LID were allocated only dynamic, and
because
I can't to know the address of the destination beforehand.

> But if you still want to use sockets-like API (to resolve
> the IB address using sockets), then you must use IP based driver (over
> InfiniBand) such as IPoIB and exchange the QP info over it, or you can
> use RDMA-CM (communication manager) that provides you sockets based
> API to manage RDMA/QP resources.

No, I don't want to use sockets-like API. I develop a problem-oriented
fully-hardware IB device, and so I want to involve the minimum number
of
protocols required for his work.

[Ali Ayoub]

Hi SiTi,

You can configure the Subnet Manager to keep the LID assignment consistent.

You can also use the Global ID (GID) which is consistent to resolve the Local ID (LID) by sending a query to the Subnet Administrator (SA), see ib_sa_* verbs for more info.

--
You received this message because you are subscribed to the Google Groups "InfiniBand" group.
To post to this group, send email to infin...@googlegroups.com.
To unsubscribe from this group, send email to infiniband+...@googlegroups.com.
For more options, visit this group at http://groups.google.com/group/infiniband?hl=en.

[Ilya Kalistru]

Thanks a lot! It will be usefull for me.

вторник, 17 мая 2011 г., 22:10:01 UTC+4 пользователь Ali Ayoub написал: