- RC (Reliable Connection) : a connection is established between endnotes, and messages are reliabled sent between them.
- UD (Unreliable Datagram): a single packet message can be sent to an endnote without first establishing a connection; transmission is not guranteed.
- UC (Unreliable Connection): a connection is established between endnodes, and messages are sent, but transmission is not guarranteed. This is optional.
- RD (Reliable Datagram): a single packet can be reliably sent to any endnote without a one-to-one connection. This is optional.
In the above, "reliably send" means that data is, barring catastrophic failure(除非災難性問題), guaranteed to arrive in order, checked for correctness, with its receipt acknowledged.
The RC, UC and RD classes also support remote DMA(RDMA): moving data directly into or out of the memory of an endnote.
來源：
http://buyya.com/superstorage/chap42.pdf
下面用qperf測試了rc, rc_rdma_read, rc_rdma_write, tcp這幾種可靠傳輸協議在message size從1Byte~8KByte的帶寬變化情況。
之前用iperf測試過56Gb網卡的tcp傳輸性能曲線如下：在單線程時的測試值與上圖的tcp測試曲線基本一致。
刀片3上的網卡標稱兼容性好，可適應56Gb IB， 40Gb Eth（40/56Gb的含義是這個意思嗎？）。
測試結果為能達到50Gb/s IB.
單線程下只能達到 12Gb/s Eth, 8線程時能達到30Gb/s Eth(在包長很大時).
包長為2KB， 8線程能達到27Gb/s Eth。
刀片2上的網卡標稱為40Gb Eth.
單線程下只能達到12Gb/s, 8線程時能達到36Gb/s.（下圖為40Gb Eth 網卡測試結果，測試的msg_size=10KB）
包長為2KB， 8線程能達到35Gb/s。
