[ofa-general] [RFC PATCH 4/4] rdma/cma: implement RDMA_ALIGN_WITH_NETDEVICE ha mode

[Or Gerlitz]

Steve Wise wrote:
> Maybe this should really be implemented in the ULP that wants this 
> behavior.  IE the ULP could register for routing/neighbour changes and 
> tear down connections and re-established them on the correct device.
>
Hi Steve,

First, registration for neighbour changes can't serve for the purpose of 
aligning RDMA traffic with the IP stack, from bunch of reasons among 
them are:

- for IB, no neighbour is created at the passive side of the unicast session

- for unicast sessions, address resolution involves ARP but the 
neighbour may be deleted by the kernel since the rdma traffic does not 
go through the stack

- for multicast sessions, no neighbour is created during address resolution

Second, the rdma-cm does well in saving the ULP from interacting with 
the network stack, that is the ULP is not aware to the routing lookup / 
neigbour / net device used for address resolution. In that spirit I 
prefer to add the registration for net events at the low level (rdma-cm).

Third, thanks for bringing the point of route changes :)

Or.