On Sat, Aug 20, 2011 at 4:47 PM, Bart Van Assche <bvanass...@acm.org> wrote: > On Mon, Aug 15, 2011 at 6:15 PM, Bob Pearson > <rpear...@systemfabricworks.com> wrote: > > I want to eventually complete the IB transport parts of the driver although > > they are not used by RoCE. They would be useful for a soft IB implementation > > with say an FPGA based MAC/PHY. The long term goal is to have a complete > > reference implementation of the IB Architecture. > > Having a complete reference implementation of the IB architecture > available would be great. IMHO at least the following should be added > to ib_rxe (not necessarily in the first version) before it can called > a reference implementation: > - Support for secondary GIDs. These make it easy to implement > fail-over in a H.A. cluster. > - Support for multicast.
More in detail, my comments with regard to multicast support in ib_rxe are: 1. Using ipv6_eth_mc_map() for mapping multicast GIDs seems an unfortunate choice to me. That choice will cause multicast GIDs to be mapped to the 33-33-xx-xx-xx-xx Ethernet address range that has been reserved by RFC 2464 for IPv6 multicast addresses. If a collision with an IPv6 multicast address occurs and IPv6 MLD snooping has enabled on the switches in the involved network then RoCE multicast won't work properly. IMHO we need a separate Ethernet address range for RoCE multicast purposes, next to the existing ranges for IPv4 and IPv6. 2. We need a way to limit multicast traffic to those switch ports on which receivers are listening. The InfiniBand architecture has such a protocol but it relies on the subnet manager, a component that does not exist in RoCE networks. And since IGMP and MLD are IPv4/IPv6 specific we need a new (IBTA-approved) protocol. 3. RFC 4541, in which IGMP and MLD snooping has been defined, will have to be extended with a paragraph about snooping the protocol defined in (2). 4. Switch vendors will have to implement the protocol item (3) refers to. Shouldn't a RoCE multicast implementation be postponed until the IEEE has assigned an Ethernet address range for mapping RoCE multicast GIDs ? Bart. -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
