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I'm trying to create a trunk between two NetGear switches using SFP's or DAC cables. RJ45 could work too, but I'm right at the edge of the number of ports, so if I can use the SFP ports then that's my preferred option. All switches are at the latest available firmware.
My current setup is two GS324T switches, connected with two short Ubiquity DAC cables, that works well.
I have previously tried a GS324T to an older GS724Tv4 and that would not work with the same DAC cables, no link.
For 10Gb I now got an XS712T and tried to use the DAC cables to connect to either the GS724T or the GS324T, no link.
The DAC cable itself links at 10Gb when connecting the two XS712 ports together.
The DAC cable itself links at 1Gb when connecting the two GS724T ports together.
This tells me the DAC cables are compatible with the SFP slots of all switches, but the switches themselves refuse to talk to eachother. What might be the problem, and are there any known good DAC cables that will work with the XS712 and one of the other switches?
Please understand that virtually all DAC cables are designated and sold as SFP+ and 10Gb - and there are reasons.
There are rare species of 1G-DAC cables. These support only 1G, and seem to identify to the switches on both ends as generic 1G SFP resp. GBIC modules.
My current setup is two GS324T switches, connected with two short Ubiquity DAC cables, that works well.
This works because this switch model does allow using (passive) DAC. While it's not officially supported, the manual does warn that the max length DAC workable is 5 meters.
For 10Gb I now got an XS712T and tried to use the DAC cables to connect to either the GS724T or the GS324T, no link.
This won't make a 10Gb - because neither the GS724T nor the GS324T have SFP+ ports. Here we need to understand that -no- SFP, SFP+, QSFP, ... do something we're used on Ethernet copper links: There is no link auto-negotiation, neither end-to-end not say on the PHY link between the modules. Exceptions are only SFP and SFP+ Ethernet RJ45 modules.
The DAC cable itself links at 10Gb when connecting the two XS712 ports together.
Of course, this is intended to work and supported on SFP+ ports, also because bot ends are 10Gb. But again: Always check what the switch vendors are supporting!
This tells me the DAC cables are compatible with the SFP slots of all switches, but the switches themselves refuse to talk to eachother. What might be the problem, and are there any known good DAC cables that will work with the XS712 and one of the other switches?
Afraid no.
This does just proof that certain switch combinations are workable with 10Gb SFP+ DAC on 1Gb SFP ports. The same applies for purpose designed 1Gb SFP "DAC" - these might work between the XS SFP+ and the GS SFP ports - very similar to real SFP-fiber modules and a dual-fiber patch cable. No-name SFP Gigabit multi-mode fiber modules and patch cables are so inexpensive that it does not make much sense to search the rare SFP-"DAC" type cables.
Said that: Avoid "special" module variants like BiDi (single fiber) - this requires again dedicated support on the switches.
Please understand that virtually all DAC cables are designated and sold as SFP+ and 10Gb - and there are reasons.
There are rare species of 1G-DAC cables. These support only 1G, and seem to identify to the switches on both ends as generic 1G SFP resp. GBIC modules.
My current setup is two GS324T switches, connected with two short Ubiquity DAC cables, that works well.
This works because this switch model does allow using (passive) DAC. While it's not officially supported, the manual does warn that the max length DAC workable is 5 meters.
For 10Gb I now got an XS712T and tried to use the DAC cables to connect to either the GS724T or the GS324T, no link.
This won't make a 10Gb - because neither the GS724T nor the GS324T have SFP+ ports. Here we need to understand that -no- SFP, SFP+, QSFP, ... do something we're used on Ethernet copper links: There is no link auto-negotiation, neither end-to-end not say on the PHY link between the modules. Exceptions are only SFP and SFP+ Ethernet RJ45 modules.
The DAC cable itself links at 10Gb when connecting the two XS712 ports together.
Of course, this is intended to work and supported on SFP+ ports, also because bot ends are 10Gb. But again: Always check what the switch vendors are supporting!
This tells me the DAC cables are compatible with the SFP slots of all switches, but the switches themselves refuse to talk to eachother. What might be the problem, and are there any known good DAC cables that will work with the XS712 and one of the other switches?
Afraid no.
This does just proof that certain switch combinations are workable with 10Gb SFP+ DAC on 1Gb SFP ports. The same applies for purpose designed 1Gb SFP "DAC" - these might work between the XS SFP+ and the GS SFP ports - very similar to real SFP-fiber modules and a dual-fiber patch cable. No-name SFP Gigabit multi-mode fiber modules and patch cables are so inexpensive that it does not make much sense to search the rare SFP-"DAC" type cables.
Said that: Avoid "special" module variants like BiDi (single fiber) - this requires again dedicated support on the switches.
My hope was that, although unsupported, it would work. The DAC cables are only 30cm, no issue there. The XS712 has 1/10Gb indicators on the SFP ports, which I had hoped would auto-negotiate to 1Gb when the other side was on 1Gb. I guess that was too optimistics.
So long story short, I can only get a connection between the XS712 and the GS324 by using real optical 1Gb SFPs, or sacrifice RJ45 ports on the GS324 and use generic Ethernet cables.
