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Re: CM1200 slows down after 24-48 hours of uptime when using link aggregation

Since I originally posted about my CM1200 link aggregation performance degradation I have found that performance can be restored without a power cycle or modem reset.  Performance can be restored by a link disable / enable. This can be done by disconnecting and reconnecting one of the Ethernet cables or by disabling and enabling one of the switch ports that the CM1200 is connected to. When I take either of these actions full performance is immediately available. Then after another two to four hour time period performance will again be severely degraded. Repeating the change of port state will again restore performance. The change of port state to restore performance can be done on either of the connected ports.

 

From my testing a down/up of one of the connected ports has restored performance multiple times, but each time performance degrades after two to four hours. The only result of my testing that I did not expect was that when in degraded mode if I disabled one port and left it disabled, performance was restored to what one would expect in a non port aggregation mode. However, again after two to four hours performance degraded. I then had to down/up the port that was active to restore performance.

 

In terms of degradation my download speeds drop from 1150 Megabits to 20 to 25 Megabits. My upload speeds drop from 40 Megabits to 20 to 25 Megabits.

 

I have an open case with Netgear support on this problem.

Message 51 of 151
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Re: CM1200 slows down after 24-48 hours of uptime when using link aggregation

Thanks for the quicker fix! Can confirm that this works, so you don't need to always reboot. I wish Netgear would acknowledge this or push out a firmware update. I'm considering returning this modem before my return window is up and buying one of the many other modems mentioned in this thread that work with WAN Aggregation and do not have slowdowns after 2-4 to 24-48 hours.

Model: CM1200|Nighthawk Multi-Gig Speed Cable Modem
Message 52 of 151
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Re: CM1200 slows down after 24-48 hours of uptime when using link aggregation

After finding an undocumented telnet interface on the switch my CM1200 is connected to I now have a script to telnet to the switch disable and enable ports and restore performance.  I have run this script multiple times over almost a week with performance being restored each time.

- telnet to switch

- disable the first port of the CM1200 connection,  delay 5 seconds, enable the port

- delay 5 seconds

- disable the second port of the CM1200 connection,  delay 5 seconds, enable the port

- quit

I believe this script can be refined to reduce the delays and only disable one port, but I have not had time to refine further so I took the conservative approach and it works in my environment.  If this continues to work, I plan to automate this process to run periodically until there is a fix for this problem or until a modem with a 2.5 Gb or above interface is available.

 

Message 53 of 151
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Re: CM1200 slows down after 24-48 hours of uptime when using link aggregation

So I have not been commenting on this in a while because I figured that I would just watch how many people complaing about the CM1200.  The last time I was on, some mentioned that I need to post a pic of the uptime, so I decided to.....  I will also post a pic of the speedtest from the NIGHTHAWK AX8

Message 54 of 151
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Re: CM1200 slows down after 24-48 hours of uptime when using link aggregation

@CGASTON This is more complicated then just the uptime of the device, i'm not sure you fully understand the problem but I'll try once more. "When the CM1200 has LACP/LAGG enabled the modem slows down to 20-40mbps over a few hours. The device works normal when not using LACP. The modems firmware is broken when using LACP but otherwise it works normal. Show us that you have LACP enabled on the CM1200 and your AX8 then we can talk, otherwise this problem does not apply to your configuration and thats why its working for you.

 

 

Message 55 of 151
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Re: CM1200 slows down after 24-48 hours of uptime when using link aggregation

Hi,

I have the same issue. Comcast or Netgear for now has no solution. What is the process to return the modem and get refunded?

Thanks,

Gregor

Message 56 of 151
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Re: CM1200 slows down after 24-48 hours of uptime when using link aggregation

Are you within your return window from who you bought it from? if so return it to them and get a MB8600 or SB8200

Message 57 of 151
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Re: CM1200 slows down after 24-48 hours of uptime when using link aggregation

No, I just checked on Best Buy. Return window ended in August. I guess, I lost $200. 

Message 58 of 151
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Re: CM1200 slows down after 24-48 hours of uptime when using link aggregation

If your a rewards member you have 30 days. Good luck.
Message 59 of 151
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Re: CM1200 slows down after 24-48 hours of uptime when using link aggregation

If you have Best Buy Elite rewards status, the return window is 45 days.

Message 60 of 151
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Re: CM1200 slows down after 24-48 hours of uptime when using link aggregation

In response to the Netgear support case that I opened on this issue, the latest information I have is that the engineers are sure they are going to fix this issue, but there is no ETA for the fix.

 

The information I posted a week ago about scripting a shutdown and no shutdown on the switch ports the CM1200 is connected to has continued to work for me to restore performance with no reboots of the CM1200 required.

Message 61 of 151
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Re: CM1200 slows down after 24-48 hours of uptime when using link aggregation

No way to do this without a managed switch? Running an R7960P and CM1200. I have to remote into the PC and into the web interface to reboot it. Could I disable and re-enable the LACP function to gain the same effect?

Message 62 of 151
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Re: CM1200 slows down after 24-48 hours of uptime when using link aggregation

I disabled port aggregation and asked Comcast to boost up my speed and lock it down.

Message 63 of 151
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Re: CM1200 slows down after 24-48 hours of uptime when using link aggregation

I will swtich back to single WAN port and have them step me down in service speed for time being. I'm running firmware version V1.02.01 anyone else running something different? 

Message 64 of 151
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Re: CM1200 slows down after 24-48 hours of uptime when using link aggregation

Firmware Version V1.02.02

Message 65 of 151
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Re: CM1200 slows down after 24-48 hours of uptime when using link aggregation

So even with a .02 firmware you still see the same issues. 

Message 66 of 151
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Re: CM1200 slows down after 24-48 hours of uptime when using link aggregation

Yes, the degradation I am seeing is with the .02 firmware.  

Message 67 of 151
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Re: CM1200 slows down after 24-48 hours of uptime when using link aggregation


@ray102382 wrote:

No way to do this without a managed switch? Running an R7960P and CM1200. I have to remote into the PC and into the web interface to reboot it. Could I disable and re-enable the LACP function to gain the same effect?


The CM1200 reboots when you enable LACP so a disable and re-enable of LACP on it may restore performance, but with a couple minutes or more outage.  If you can disable / enable LACP on the device that the CM1200 is connected to that may restore performance.

Message 68 of 151
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Re: CM1200 slows down after 24-48 hours of uptime when using link aggregation

I tried to disable it on the R7960P and it triggers a reboot as well. So I guess no easy way around it. I removed the second connection and turned of aggreation all together for now. 

Message 69 of 151
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Re: CM1200 slows down after 24-48 hours of uptime when using link aggregation

I stumbled on this thread after purchasing one of these modems. Just wondering if there has been anything new on this problem? NETGEAR?

Model: CM1200|Nighthawk Multi-Gig Speed Cable Modem
Message 70 of 151
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Re: CM1200 slows down after 24-48 hours of uptime when using link aggregation

Yea, this is exactly what I thought. 

Message 71 of 151
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Re: CM1200 slows down after 24-48 hours of uptime when using link aggregation

What does the wrong and right frequency look like?

Message 72 of 151
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Re: CM1200 slows down after 24-48 hours of uptime when using link aggregation

In case people are still looking for hard proof, I've taken the liberty of recording a video of my own experience in ownership of a CM1200. I'm using Comcast Xfinity in Portland, Oregon, my CM1200 is running firmware V1.02.02, and it's connected via 802.3ad (LACP) link aggregation to a Netgear SG-4860 running 2.4.4-RELEASE-p3. My current speed tier is 175/5, but I was paying for Gigabit internet shortly after moving into this apartment and was seeing the same symptoms everyone here's been reporting: after about 24 hours of uptime, bandwidth is throttled to around 20Mbps up/down. Prior to this weekend, I thought that reboots were the best way to get service back, but resetting one of the ports in the LAGG group on my pfSense appliance also works -- I'd like to thank everyone who suggested this.

 

 

As you can see in this video, my modem's been online for around 5 days, and though it isn't shown, my pfSense appliance has been online for about 9 days. After bouncing one of the interfaces in the LAGG group, Comcast's own speed test (which you should assume is exaggerating the speed of my connection) reports that my speed increases ten-fold. The last interface reset I'd made to a port in the LAGG group was a little under an hour prior, so to put this another way: it takes less than one hour for speed to degrade by 90%. I believe the bandwidth degradation is caused by utilization, but whether that's raw packet throughput or connections being made, I couldn't tell you without more information, and modems are unfortunately locked down.

 

 

Model: CM1200|Nighthawk Multi-Gig Speed Cable Modem
Message 73 of 151
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Re: CM1200 slows down after 24-48 hours of uptime when using link aggregation

I RMA'd my CM1200 modem, and I am still seeing the same exact slow down after a few hours. I have a 1 Gig plan, so I'm not making use of the aggregate ethernet ports. My ISP is Comcast in Northern California. Anyone know how to get their money back from Netgear?

Model: CM1200|Nighthawk Multi-Gig Speed Cable Modem
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Re: CM1200 slows down after 24-48 hours of uptime when using link aggregation

 
Message 75 of 151
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