AOC cables have capability issue?

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wittyet

New Member
May 19, 2023
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I recently got two EX3300 for the 10G ports, and bought some huawei sp310 nic cards.
the cards are installed in Dell R530 and R430, they both run proxmox, and in the proxmox -> network UI I can see the card, and I can also see the card in passthough list.

I tested all 10G ports with a DAC cable borrowed from a friend, they all connected fine and the green leds light up and blink as they should. in ex3300 dashboard gui the ports show green, up and run.

then I went out to buy my own cable, little did I know that there are two kinds of cable that look the same, and the cables I received are AOC cables.
Gigalight 10G SFP+ Active Optical Cables P/N: GSS-MDO100

now when I connect between sfp+ ports on two switches or host to switch, none of them works.
I already deleted all vc ports,
actually the 3rd port on a switch tries to negotiate with a host, but the green leds went off really quick and that's it. It feels like they can't agree on anything to establish a link.

I really appreicate knowledge ppl can shed some lights on the issue.

is this a capability issue of the AOC cable, I am thinking to also directlly connect two hosts with the cable and see if that works.
 

joeribl

Active Member
Jun 6, 2021
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One thing which is important with DAC, AOC, that both sides are compatible with the cable, well actually with the SFP module (coding). It is not like with a UTP cable, there is actually logic inside the SFP connector/module.

Some brands of switches/nic/firewall are very picky, some accept with a warning and some simply refuse to work with an incompatible module, but I dont know what is the case with the EX3300 or the SP310 NICS.

For instance Fortinet will accept unknow modules, but will give a warning. For HPE you sometimes have a very hardtime finding a compatible DAC, to match between different family switches or adapters.

I think you should see some errors in the logs, like incompatible module found or something similar.
 
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wittyet

New Member
May 19, 2023
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Thanks for the reply.
I spent yesterday to rule out possible problems one by one.
cards and cables work when they are connected directly.
and I am sure those 10G ports work fine as I tested with borrowed DAC

and funny thing is the moment I plug one end into switch, the connection went away.......

I am looking through the files, and I think I found something
 
Last edited:

joeribl

Active Member
Jun 6, 2021
136
46
28
Thanks for the reply.
I spent yesterday to rule out possible problems one by one.
cards and cables work when they are connected directly.
and I am sure those 10G ports work fine as I tested with borrowed DAC

and funny thing is the moment I plug one end into switch, the connection went away.......

I am looking through the files, and I think I found something
So most likely the switch is not accepting the SFP module (which is integrated in the AOC) for compatibility reasons. The AOC is an active component and not something dumb like UTP cable.
 

wittyet

New Member
May 19, 2023
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yes, after looking through the log files, i found the switch complains about the EEPROM mis programmed.
bought a 10Gteck DAC cable and the connection picked up instantly
 

blunden

Active Member
Nov 29, 2019
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yes, after looking through the log files, i found the switch complains about the EEPROM mis programmed.
bought a 10Gteck DAC cable and the connection picked up instantly
Yeah, an AOC cable is basically a fiber cable with transceivers fused directly to the fiber instead of using regular connectors. Therefore you have all the same SFP module compatibility issues as with regular fiber transceivers, as others have mentioned. If your cable has a writable EEPROM it could probably be reprogrammed to work by spoofing a compatible transceiver since it's rarely anything more than a vendor lock. After all, vendors would prefer if you spend thousands of dollars on their own branded transceivers instead of maybe 50-100 dollars on a third-party one that will likely work just as well. That's why companies like FS.com and others that sell generic transceivers programmed to the vendor of your choice exist. They also sell you a box so that you can reprogram the transceiver EEPROM yourself if you need to.

There are also Active DACs which support longer distances than passive DACs. If they fit your purpose, passive DACs are both cheaper and lower latency.