Slow uplink on MS130-24X on 2.5G ports only

[LOTRouter]

I ran into a strange issue yesterday when using an MS130-24X plugged into a Spectrum Internet router.  If I plugged my PC directly into the Spectrum router, I got full speed (930/35).  If I plugged my PC into the MS130-24X which was also plugged into the same Spectrum router, I got really bad upload speeds (350/0.7).  After troubleshooting for awhile, I finally moved the connection from the Spectrum router to a NON-2.5G port, and I suddenly got full speed with my PC connected to the MS130.  I checked, and it properly negotiated 1G full duplex when connected to a 2.5G port, but had completely borked upload speeds.  Is this a known issue with the MS series switches 2.5G ports?

I first noticed this issue due to bad upload speeds when wirelessly connected to an MR57 connected to the same MS130, so it most certainly was not an issue with my PC's NIC.  Moving the Spectrum link to a 1G only port resolved the Wi-Fi issue as well.

[PhilipDAth]

Interesting.  What speed did the 2.5G report it was running as?  Gigabit?

[LOTRouter]

Yes, it reported as full-duplex Gigabit.  I assume I wasn't getting full download speeds due to dropped ACK packets on upload.

[cmr]

We have an MR44 plugged into one of the 2.5Gb ports of an MS130-12X and it keeps going into repeater mode.  New Cat6a cabling and not overly long...it had no issues with the MS220-8P that was there before...  I'll see if I can go there and do some direct testing as it may be related!

[LOTRouter]

Be forewarned that while ports 17-18 are not labeled as 2.5G on the MS130-24X, they will connect at 2.5G speeds.  I'm not sure if the MS130-12X has extra unlabled 2.5G ports, but I'd be sure to go with lower numbered ports, just to be sure.

[GIdenJoe]

Interesting.  Do you see any CRC errors in the live packet counters?
Is the router also negotiating correctly with that port or do you see a different negotiated speed on the router?
Remember if negotiation fails you could get stuck in a 100 Mbps half duplex setting causing plenty of collisions.

[LOTRouter]

No CRC errors, negotiated to 1G-Full, and I get greater than 100M downlink, just .07 uplink when connected to a 2.5G port.  If I move the exact same cable to an identically configured 1G only port on the MS130 then I get full speed both directions.

[rstensholt-sc]

Did you ever find a fix?  Im having a similar(same issue) with Fios and a ms130 as my breakout.  Same config on a ms220 and no upload issues.  I have a 500/500, but with the ms130 in the way, i get 500/3mbps.

[cmr]

Have you updated to 17.2.1?  That is supposed to fix it.

[LOTRouter]

I never found a solution, other than moving the port to a gigabit only interface.  While the switch has since been upgraded to the latest firmware, it's a remote site and I don't plan on going there anytime soon to move the link.

[ESMichal]

We see very similar issue when our MX68 gateway (MX 18.211.5.2) is connected to a 5Gbit port on MS150-48MP-4X switch (MS 17.2.1). The negotiated link speed is 1Gbps. The measured download speed is fine (800 - 900 Mbps) but the upload speed is very slow (100 - 150 Mbps).

When we connect the gateway to 1Gbit port on the MS150 we get expected 800-900 Mbps on both download and upload.

I can reproduce this problem on all 5 Gbit ports. It does not matter where is the test device connected:

• MX: 5, Test device: 5 -> Bad upload
• MX: 5, Test device: 1 -> Bad upload
• MX: 1, Test device: 5 -> OK upload
• MX: 1, Test device: 1 -> OK upload

We have a bunch of CW9166I connected to 5Gbit ports on MS150. When the gateway is connected to 1Gbit port and the test device to Wi-Fi, we measure 300-450 Mbps on both download and upload. When  the gateway is connected to 5Gbit port, we measure 250-450 Mbps download but only 3-20 Mbit on upload. This is very weird since the "bottleneck" does not look to be static but proportional.

We first noticed this problem on older version of MS firmware. Upgrading to 17.2.1 has not resolved it.

[cmr]

@ESMichal the fact that a 1Gb device has issues with a mGig port is annoying, but that fact that a 5Gb device has even worse issues is ridiculous!  Is the 9166I syncing at 5Gb and just being rubbish?  If so what happens if you force 2.5Gb or 1Gb?

[ESMichal]

There is no problem with any other device on 5Gbit ports. CW9166I appear to be working just fine

It's just the uplink connection to gateway which triggers the upload problem when gateway is connected it to 5Gbit port. Other devices including CW9166I do not produce any problems I am aware of.

Good idea. I will try to force 1Gbit on 5Gbit port where the uplink is connected to see if the problem is still reproducible.

[cmr]

Ah, that makes more sense (though obviously still isn't good).  Can you not use one of the SFP+ ports for the uplink?

[ESMichal]

Forcing the 5Gbit port the gateway is connected to 1Gbit has no effect. Slow upload speed is still reproducible.

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@cmr wrote:

 Can you not use one of the SFP+ ports for the uplink?

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Why do you ask? To see if the problem happens on SFP+ ports as well?

To test that we would have to obtain a different gateway (with SFP+) or get Ethernet->SFP+ converter for MX68. We won't do that since we have a more simple workaround.
We just connect the gateway to regular 1Gbit RJ45 port on the MS150. There is no upload problem there.

[cmr]

@ESMichal, that was exactly the point, I'd guess that it does not.  However as you have an MX68 just using a 1Gb port is the best answer, even though it doesn't tell us why the mGig port is misbehaving with 1Gb devices as the uplink...