Is this just some marketing buzzword, or is there any relevance/importance calling the cable “Direct Attach”?
An example is given on the product page of S+DA0001 that it can be used to connect 2 switches together.
I asked the support whether that cable can also be used to connect a server to the switch and the support said yes.
So, then where is the difference, if any? Why is it then called “direct attach”? Is there also an “indirect” attach method possible?
Curious mind wants to know…
Btw, another related question: what’s the difference between passive direct attach cable and active direct attach cable?
There are the DAC cables that might be Active or passive and there are the AOC Active Optical Cables… As well as the SFP, SFP+, QSFP Modules etc…
You can find a lot of info with just a google search about each of them…
Basicly because there is no detacheable transmission medium involved. The cable and transceivers are fixed together.
Non DA SFPs have connectors for a fiber cable.
Btw, another related question: what’s the difference between passive direct attach cable and active direct attach cable?
Passive DA cables only have some passive components for impedante matching the signal pins to a twinax cable. Active DA
cables have some active components which allow them to work over longer distances.
If you don’t need long runs, passive DA cables have an advantage: lower power consumption and lower cost.
A follow-up question:
In ancient Ethernet times one had to use a “crossover cable” to attach 2 PCs directly (w/o going over a hub or switch).
Is such a special crossover cable necessary also with SFP/SFP+ ? (I guess & hope not )
When you have two SFP optical modules for multimode fiber and you link them using a fiber patch cable, indeed you need to watch out for the TX/RX crossover.
However, the connectors can be detached and swapped when it is incorrect, so you do not need a special crossover cable.
(and normally you would not encounter this situation when everything is wired “standard”, i.e. all patchcables and all cable runs between patchpanels are wired as crossover)
For SFP/SFP+ with S+DA0001 what he wrote was very informative, at least for me as a newbie in 10G, SFP+, DAC.
I think S+DA0001 does not use optical fiber but copper cable, right? Then the case with AOC is IMHO not that relevant then.
The point is not who takes the glory of a correct answer or not…
But if someone searches the posts and falls under this answer he will find as a solution something that is actually wrong..! So he will learn it wrong!
Thats the point of marking an answer as a solution.. so others can learn from that and solve their problems…
So from the above answer i might buy an AOC cable because according this solution it has detachable modules, and when i get it on my hands, guess what? It wont be as someone said here!!!
