MLNX OFED 2.2 is preferred and it has significant improvements in both stability and performance of IPoIB. However if you have older Linux versions that are not supported by 2.2 (like RHEL 5.x kernels) then you have to use 1.5.3 on those systems. Both versions can coexist, just be aware that they have different default settings for IPoIB modes – it is CM for 1.5.3 and UD for 2.2. Links between 1.5.3 and 2.2 systems (with default settings) will negotiate to UD so performance will be limited by performance of UD on 1.5.3 which is lower than CM on 1.5.3. Setting 2.2 systems to CM will give you better performance on links with 1.5.3 systems. If both ends are 2.2 preferred mode is UD (default): although both UD and CM have good performance on 2.2, UD has a bit higher performance and better scales with a big number of connections. On firmware: MLNX OFED installation by default will do firmware upgrade on your Mellanox branded cards (OEM cards by HP or others will not be upgraded). You can check card PSID with ibv_devinfo (see http://www.mellanox.com/page/firmware_HCA_FW_identification) – for Mellanox cards PSID always starts with “MT”, for example: MT_1100110019. With actual PSID you can always find proper fw at http://www.mellanox.com/page/firmware_download but perhaps easiest is to allow MLNX OFED installation script to do the upgrades to versions required. Once f/w is upgraded – your ConnecX2 and ConnectX3 cards will work just fine.
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