 Since RoCEv2 packets are routable the RoCE v2 protocol is sometimes called Routable RoCE or RRoCE.Although in general the delivery order of UDP packets is not guaranteed, the RoCEv2 specification requires that packets with the same UDP source port and the same destination address must not be reordered.In addition, RoCEv2 defines a congestion control mechanism that uses the IP ECN bits for marking and CNP frames for the acknowledgment notification.