Stacking two Netgear GS748TS switches via HDMI - only 1Gbps trunk bandwidth?
You need to ensure you have a HDMI v1.3 or 1.4 compliant cable to achieve this, even then you'll never see more than 8.16Gbps due to overhead.
I've never seen HDMI being used this way, most sysadmins just buy switches with 10Gig ethernet ports to deal with the...erm, 10Gig ethernet. I like the ideal of the HDMI but it sounds a bit fragile a solution (as is the case here) and it seems a bit 'prosumer' to me. Imagine it's cheap though.
the stacking ports are full duplex so a single cable completes the ring.
A hmdi plug is probably stronger than a LC fibre plug, but as the HDMI loop is in the rack (I doubt you could run a 10m HDMI and have a working stack) strength/latching capacity it a bit irrelevant.
I would say, having bought stacking kits in the past for several hundred pounds a £3 HDMI lead from CPC suites me fine!
As for dodgy test topology, I don't see how you can test a 10GB link without 10GB infrastructure, to find true speed you would surely need to have a couple of servers with 10 concatenated 1GBs connections, I suspect as above the test topology used showed results for a single port, as I fail to see how it could scope the backplane bandwidth.
How are you testing exactly? It sounds like its your testing method at fault, not the switches or cable. The fact its rounding off to a neat 1gbps would dismiss the claims the cable quality is at fault.
I guess you are either testing with either,
- 1 server and 3 clients
- 2 servers and 2 clients
The former will always be limited to the connectivity of the server, so if its a non bonded (LACP) connection, you'll only ever see a 1gbps cumulative result.
The latter, if both tests were run simultaneously, should see a total of 2gbps throughput across both iperf tests. So if you're not getting this result, but are using this method - then it sounds like a config issue.
Surprisingly, the netgear forums for the prosafe kit are pretty useful, they have a few mods on there who are higher level netgear techs; so its definitely worth pursuing a solution there too.