network and prevents RoCEv2 packets from traveling through a wide area network such as the internet which is not reliable. Another solution is to add reliability to the RoCE protocol (i.e., reliable RoCE) which adds handshaking to RoCE to provide reliability at the cost of performance. The question of which protocol is better depends on the vendor. Chelsio recommends and exclusively support iWARP. Mellanox, Xilinx, and Broadcom recommend and exclusively support RoCE/RoCEv2. Intel initially supported iWARP but now supports both iWARP and RoCEv2. Other vendors involved in the network industry provide support for both protocols such as Marvell, Microsoft, Linux and Kazan. Cisco supports both RoCE and their own VIC RDMA protocol. Both Protocols are standardized with iWARP being the standard for RDMA over TCP defined by the IETF and RoCE being the standard for RDMA over Ethernet defined by the IBTA. Criticism Some aspects that could have been defined in the RoCE specification have been left out. These are: How to translate between primary RoCE v1 GIDs and Ethernet MAC addresses. How to translate between secondary RoCE v1 GIDs and Ethernet MAC addresses. It is not clear whether it is possible to implement secondary GIDs in the RoCE v1 protocol without adding a RoCE-specific address resolution protocol. How to implement VLANs for the RoCE v1 protocol. Current RoCE v1 implementations store the VLAN ID in the twelfth and thirteenth byte of the sixteen-byte GID, although the RoCE v1 specification does not mention VLANs at all. How to translate between RoCE v1 multicast GIDs and Ethernet MAC addresses. Implementations in 2010 used the same address mapping that has been specified for mapping IPv6 multicast addresses to Ethernet MAC addresses. How to restrict RoCE v1 multicast traffic to a subset of the ports of an Ethernet switch. As of September 2013, an equivalent of the Multicast Listener Discovery protocol has not yet been defined for RoCE v1. In addition, any protocol running over IP cannot assume the underlying network has guaranteed ordering, any more than it can assume congestion cannot occur. It is known that the use of PFC can lead to a network-wide deadlock. Vendors Some vendors of RoCE enabled equipment include: Mellanox (acquired by Nvidia in 2020, brand retained) Emulex (acquired by Broadcom) Broadcom QLogic (acquired by Cavium, rebranded) Cavium (acquired by Marvell Technology Group, rebranded) Huawei ATTO Technology Dell Technologies Intel Bloombase Xilinx (via FPGA soft IP core)