Hi Faisal,
By the terms you are using (SFT and ALB), it appears you are talking about Intel NIC's. The first thing to keep in mind is that much of the confusion you are encountering is because each vendor has there own terminology for types of teaming, as well as different ways of doing things.
Since many of these "modes" are proprietary, we must rely on the vendors to provide us accurate descriptions on how "their" solution works (unlike teaming based on 802.3ad, aggregation, which is standards based, and well defined, documented and understood.). To this end you really have to rely on the vendor to provide the best guidance, as they are the only ones who really know what their code is doing.
Looking specifically at some of the modes you mention, we can take a look at an Intel link that discusses their teaming here: http://support.intel.com/support/network/sb/CS-009747.htm
At the link above, from what I can see, SFT describes simple Active/Standby type teaming, while ALB is a proprietary Active/Active teaming. The problem is, the vendor that has developed the software does not provide (at least not in the descriptions at this link) enough information to make an intelligent decision. Add to that, that since this is not standards based (and openly documented to the world), they can (and do) change the operation at any time with a new release of code, and your understanding of what "was" is no longer valid with what now "is".
So to try to answer you're final question: "I just want to know when do we use SFT with technical justification and when do we use ALB if some one can provide will be a great help for me", for an official answer, I recommend you go to Intel and ask them this question, as they are the only ones that truly know what their teaming algorithms are doing, and can thus make such an authoritative recommendation.
As for my opinion (and that is all you can really get from anyone other then Intel), owing to many reasons I've already discussed in previous threads, SFT (Active/Standby) is the safest way to go. It is the simplest and least likely to have unexpected interactions with upstream networking devices. If you want to use Active/Active, use a teaming method based off of 802.3ad and be sure to only connect the NICs to a common logical/physical upstream switch, and configure the upstream switches NIC-facing ports to match the 802.3ad setting on the team).
As I've noted in other threads in this forum, I am not saying you can not do proprietary forms of A/A teaming such as ALB (I've tried most of them at one time or another myself). I'm just saying there are too many variables/unknowns for me to ever generically make a statement such as "ALB will always work and is recommend in this or that specific situation". I -can- make that statement with A/S (SFT) and 802.3ad types of teams.
Maybe someone else on this list has a more definitive answer, but that is the best I have.
Thanks, Matt
