Perplexing MoCA issue

[FatherTime]

So I'll start by saying I'm new to MoCA. Short story, when copying large files (60+GB) from PC to media storage over the MoCA network, the transfer rate is around 20-22 MB/sec. When copying the same file from the PC to media storage over ethernet (really long one strewn across the house), I am seeing speeds of 90-95MB/sec. I'm ok with those speeds as they're getting copied to a 1Gbps device to a 5400rpm HDD. I can't for the life of me figure out why I am not seeing the same speeds across the MoCA network as i am going through just the ethernet cable.
Specs:
-PC has 2.5Gbps nic
-Router has 2.5Gbps ports
-MoCA GoCoax MA2500D
-MoCA link speeds are 2.5Gbps
-MoCA PHY rates are 3500ish on everything
-Ethernet cables are new Cat6a cables
-Coax cable is new RG6 cable
- MoCA devices given static IP addresses matching my subnet mask
-Settings left the same from the factory other than IP Address
-One of the MoCA devices came with older firmware (2.0.14 or something) and I was given the new firmware (2.0.16 or something) which I updated to. The other device already came with the newer firmware.
-Only one (in the office) is the master (Preferred NC box checked).

Test Case:
Not using ANY splitters, filters, other devices...
Really simple test case to see the speeds.......
PC->Router->MoCA->MoCA->Storage Device = 20-22MB/sec
PC->Router->Ethernet->Storage Device = 90-95MB/sec

There isn't too much to change in the MoCA admin pages. Not sure what they all mean though.

Does anyone have any ideas? Please. lol

 

[degrub]

MOCA, like wifi is half duplex. So best sustained between a pair of modems between two devices should be about 1.25 Gbit/s *0.9 (overheads) = ~ 1 Gbit or at least 100 Mbyte/s

One thing that can be helpful is to connect the ethernet side of the moca modem into a switch rather than direct. There may be buffering issues or MTU/frame mismatch. Are you running Jumbo frames ? don't.

Do you have just a single pair of moca modems or is this part of a larger moca network ?

There should be diagnostics page that will give you a clue about mangled packets, retransmits, etc. The modems appear to be syncing at the correct value.

Change out the ethernet cables that you are using to connect the moca modems to the router and to the device.

If you have two PCs running windows with the same 2.5 Gbit/s ethernet connections, get a copy of iperf V2 (not V3 which is for linux), run parallel streams, maybe 10 or 20, in each direction and see what transfer bandwidth you get over moca and over direct ethernet.

GoCoax has been helpful in the past in resolving issues, so i would contact their support with what you are seeing.

 

[FatherTime]

MOCA, like wifi is half duplex. So best sustained between a pair of modems between two devices should be about 1.25 Gbit/s *0.9 (overheads) = ~ 1 Gbit or at least 100 Mbyte/s

One thing that can be helpful is to connect the ethernet side of the moca modem into a switch rather than direct. There may be buffering issues or MTU mismatch. Are you running Jumbo frames ? don't.

There should be diagnostics page that will give you a clue about mangled packets, retransmits, etc. The modems appear to be syncing at the correct value.

Change out the ethernet cables that you are using to connect the moca modems to the router and to the device.

If you have two PCs running windows with the same 2.5 Gbit/s ethernet connections, get a copy of iperf V2 (not V3 which is for linux), run parallel streams, maybe 10 or 20, in each direction and see what transfer bandwidth you get over moca and over direct ethernet.

GoCoax has been helpful in the past in resolving issues, so i would contact their support with what you are seeing.

Thank you for the prompt reply.
-I tested without the switch for simplicity, but normally it is indeed connected to a 2.6Gbps unmanaged switch. Same results both ways though.
-Not sure how to set Jumbo Frames, but I'm pretty sure I'm NOT using them.
-I haven't seen mangled packets or retransmits, but dropped/bad packets are listed. Those values are always zero.
-The moca modems are directly connected to the router and the device.
-I was hoping to run iperf tonight, hopefully usable information is produced.
-I had contacted GoCoax, but their email turnaround time is painfully slow. It takes days to get a reply and sometimes miscommunications in emails requires days worth of re-sent information. I haven't given up with them yet though.

 

[degrub]

Thank you for the prompt reply.
-I tested without the switch for simplicity, but normally it is indeed connected to a 2.6Gbps unmanaged switch. Same results both ways though.
-Not sure how to set Jumbo Frames, but I'm pretty sure I'm NOT using them.
-I haven't seen mangled packets or retransmits, but dropped/bad packets are listed. Those values are always zero.
-The moca modems are directly connected to the router and the device.
-I was hoping to run iperf tonight, hopefully usable information is produced.
-I had contacted GoCoax, but their email turnaround time is painfully slow. It takes days to get a reply and sometimes miscommunications in emails requires days worth of re-sent information. I haven't given up with them yet though.

Screen shots can be useful without having to translate.

So, if i understand the original post correctly, both moca modems are connected to 2.5 Gbit/s router/switch ports and the storage device has a 1 Gbit/s interface and is always connected to either the router switch or the unmanaged 2.5 Gbit/s switch ?

When you did the ethernet cable versus moca test all you did was plug in the ethernet cable to the router 2.5Gbit port and the switch 2.5Gbit port while unplugging the moca modems from each ?

You were using a simple file copy command in windows explorer or ctrl c, ctrl v ?

i think there have been some similar posts before about this issue.

 

[degrub]

here is one that may directly relate to what you are seeing

Need a bit of Advice getting 1/2 speed on Moca compared to Ethernet

So I'm new to Moca as it's not such a big thing here in the UK as it is in the USA (had to import the adapters from Gocoax - great company by the way) I'm having an issue where the speed i'm getting on the gocoax moca adapters is about 1/2 what I would get if I was connecting over ethernet . I'm...

www.snbforums.com

focused on iperf (note they are running wrong version for windows), but the TCP protocol may be the issue.

 

[degrub]

and the other one i was thinking of - down into the nitty gritty

MOCA 2.5 Help Needed - Why Are my Speeds Slow in 1 Direction?

I have the ScreenBeam (ActionTec) ECB7500 (moca 2.5) I have two PCs (both Win11 Pro). Both have the same specs. When i transfer from PC1 to PC2 across the 2.5Gbps network i get 285MB/s. However, when transferring the same file (after clearing the system file cache via RAMMap) from PC2 to PC1...

www.snbforums.com

 

[FatherTime]

Screen shots can be useful without having to translate.

So, if i understand the original post correctly, both moca modems are connected to 2.5 Gbit/s router/switch ports and the storage device has a 1 Gbit/s interface and is always connected to either the router switch or the unmanaged 2.5 Gbit/s switch ?

When you did the ethernet cable versus moca test all you did was plug in the ethernet cable to the router 2.5Gbit port and the switch 2.5Gbit port while unplugging the moca modems from each ?

You were using a simple file copy command in windows explorer or ctrl c, ctrl v ?

i think there have been some similar posts before about this issue.

-I'm at work and unfortunately don't have screen shots available, but can get some later.
-"So, if i understand the original post correctly" - One moca modem connected directly to the router and one connected into the switch with coax between them.
-See picture for both test scenarios.
-In both test cases I was copying the same file from the same place to the same destination. A huge .mkv file from PC to Zidoo Media Player via Samba drive mapping through Windows Explorer drag/drop.
-I have looked for similar posts with no luck.
-I appreciate your time.

 

[degrub]

Post #6 above is worth a read. Bottom line, i think you will have to significantly increase the TCP buffer in the windows machine as their iperf results show. But please read the details in the post as i may be misremembering.

 

[tgl]

Another idea that might help is to put a managed switch at the spot where there's a step-down from 2.5G to 1G line rate, and enable flow control in that switch.

(I've owned unmanaged switches that appeared to have flow control on by default, but I bet that is not universal.)

EDIT: to be clear, this is just a variant of the "buffering issues" theory that @degrub posited upthread. But I'm offering something concrete to do about it.

 

[FatherTime]

Another idea that might help is to put a managed switch at the spot where there's a step-down from 2.5G to 1G line rate, and enable flow control in that switch.

(I've owned unmanaged switches that appeared to have flow control on by default, but I bet that is not universal.)

EDIT: to be clear, this is just a variant of the "buffering issues" theory that @degrub posited upthread. But I'm offering something concrete to do about it.

The thing is though even if the switch is still in line, and the only things changed is the 2 mocas and coax cable for the ethernet cable, data transfer speeds are fine. It's only drops when the moca devices are introduced regardless if a switch is inline or not. And it drops to a silly, low speed.

 

[FatherTime]

Here are screen shots of the two moca adapters in my testing. Anything else worth noting. I can't run my iPerf tests yet but I will post that info when I can.

 

[degrub]

Were there 3 moca modems on the coax at the time of the testing ?
Probably doesn't matter much, but the bandwidth will be shared amongst the 3 moca devices. If the 3rd one happened to be active during the test, that would affect bandwidth .

Either way, TCP transfers do not like extra latency that moca introduces - approx 3 msec per pair. Basically, puts a restricter in the line from everything i have read if that buffer gets full. FLow control with a managed switch likely is sending a signal back to the sending device, a pc in this case, and telling it to stop sending for short periods and internally buffering before sending to the moca modem. WOrth a try to enlarge the buffer in the PC if that will solve it.

i haven't had the issue but all of my network is Gbit except the home run between my ONT and the ISP router which is GoCoax 2.5, original version with 1Gbit link to ONT and Router.

 

[FatherTime]

There are 3 MoCA devices on my home network although I just grabbed the screenshot just now, only two used in testing and the rates were about identical. Also, these run in full duplex, as I know you mentioned earlier that they might be in half duplex.

 

[tgl]

Also, these run in full duplex, as I know you mentioned earlier that they might be in half duplex.

Hmm, I had not heard that that was possible for MoCA. I know that the "3500Mbps" speed spec represents total available bandwidth on the line, so if two MoCA adapters actually are doing full-duplex they'd have to do so by splitting the spectrum and each transmitting at only 1Gbps-and-change. Still, even if that is happening here, that should give a better result than you're getting. I continue to be suspicious of flow-control-related issues. Once a switch or other network device starts dropping packets, TCP throughput goes to heck.

 

[tgl]

BTW, I would have posted a link to the thread mentioned in comment #6, except @degrub beat me to it. There's some history there about my own adventures getting 2.5G MoCA adapters to deliver the claimed speeds.