There is a lot of talk about how PFC makes Ethernet loss-less and suitable for FCoE or ISCSI. My question is, for single-type-of-traffic interfaces, for example ISCSI arrays connected to a Ethernet switch. Why doesn't traditional PAUSE based flow control give the same level of loss-less performance?
For example Dell claims in section 5.1 in their guide "Creating a DCB Compliant EqualLogic iSCSI SAN with Mixed Traffic" that retransmissions went from 0.315% to 0% when going from PAUSE to PFC. I just don't understand why. Both technologies works the same way with pause for xx time, and resume frames. Are the thresholds for when to send the pause frames different by default? Reason for asking is that Dell does not support running DCB between Nexus switches and Equallogic arrays, and I'm trying to understand why I couldn't just do traditional PAUSE based flow control on the interfaces between the array and the switches, as those are ISCSI only interfaces and manually map the traffic into the correct qos-group, and then do DCB with PFC on the server interfaces to have flow control only on the ISCSI VLAN. Any thoughts? _______________________________________________ cisco-nsp mailing list [email protected] https://puck.nether.net/mailman/listinfo/cisco-nsp archive at http://puck.nether.net/pipermail/cisco-nsp/
