<div dir="ltr">You may also find it helpful to have something specific to check for DNS resolution. In some systems/cases the failure to resolve an FQDN used as part of the check will show up as a generic "no/lost connection". Provided the system has the capability a set of hosts to test to could be something like localhost, the LAN default gateway, the modem's default gateway, the FQDN the system uses by default for testing, and a well known IPv4 endpoint like Google's 8.8.8.8.<br></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Thu, Nov 14, 2024 at 11:25 AM Derek Atkins via Ale <<a href="mailto:ale@ale.org">ale@ale.org</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">What concerns me is the "empty" part of your graph.. At the 45ms peak,<br>
there appears to be a section of "no response". Note that depending on<br>
the service being used, it's possible that the service is down.<br>
<br>
FWIW, I run mrtg to monitor my network -- I run pings to several different<br>
places to test latency across my uplink. Specifically, one place I ping<br>
is my 1st-hop upstream router. If that router goes down or doesn't<br>
respond, it is 100% correlated to my connection being down for everything.<br>
<br>
Of course, YMMV.<br>
<br>
-derek<br>
<br>
On Thu, November 14, 2024 11:08 am, Neal Rhodes via Ale wrote:<br>
> Thanks for the reply.<br>
><br>
> I just got off the phone with Comcast. To my delight it only took 12<br>
> minutes total.<br>
><br>
> Their criteria is, they don't get concerned until:<br>
><br>
> * Packets get lost;<br>
> * Latency exceeds 100ms.<br>
><br>
> To which I can only say, wow.<br>
><br>
> Comcast tech also says I should reboot their router. (uptime over 140<br>
> days.)<br>
><br>
> My bet is the Ubiquiti router has much tighter assumptions. Next I<br>
> need to ask them precisely what their criteria is for concluding<br>
> disconnection.<br>
><br>
> regards,<br>
><br>
> Neal<br>
><br>
> On 2024-11-14 10:56, Derek Atkins wrote:<br>
><br>
>> Hi Neal,<br>
>><br>
>> I ditto what James says (and was going to say the same thing). Take a<br>
>> laptop that you KNOW can handle 1Gb, to be sure it's not a laptop<br>
>> limitation, and then plug into the router to be sure you can show the<br>
>> issue from their CPE. Showing it from the Ubiquiti equipment is not<br>
>> sufficient.<br>
>><br>
>> Also, it helps if you can have a tech on the phone while the problem is<br>
>> occurring. I used to have Comcast Biz and would lose network every<br>
>> time<br>
>> there was a neighborhood power outage. It took a 3hr outage during the<br>
>> day and me calling just as the outage stopped for them to find the node<br>
>> with the bad battery.<br>
>><br>
>> So back to your issue. It looks like it could be a network drop, a<br>
>> DHCP<br>
>> renew that takes too long, or possibly even an upstream issue with<br>
>> Comcast.<br>
>><br>
>> Expect to spend time trying to reproduce it, especially if it's<br>
>> something<br>
>> that isn't reliably reproducible. You might also want to look at<br>
>> potential buffer bloat, and also explore the possibility of NAT Table<br>
>> overload.<br>
>><br>
>> Having said that, the RTT you see (17ms) is reasonable for a cablemodem<br>
>> plant.<br>
>><br>
>> -derek<br>
>><br>
>> On Thu, November 14, 2024 10:41 am, James Taylor via Ale wrote: My<br>
>> experience with Comcast Business says that the you need to spend time<br>
>> in the furnace room.<br>
>> They are going to test from their router and if you don't show the<br>
>> problem<br>
>> there, they are unlikely (i.e. - never) to look further.<br>
>> -jt<br>
>><br>
>> James Taylor<br>
>> 678-697-9420<br>
>> <a href="mailto:james.taylor@eastcobbgroup.com" target="_blank">james.taylor@eastcobbgroup.com</a><br>
>><br>
>> Neal Rhodes via Ale <<a href="mailto:ale@ale.org" target="_blank">ale@ale.org</a>> 11/14/2024, 10:36 AM >>><br>
> This feels like a classic three party finger pointing exercise, and I'm<br>
> doing a bit of research before we jump in.<br>
><br>
> A couple of years ago, our church put in a sophisticated (at least by MY<br>
> Measure) Ubiquity Unifi Mesh network, mostly to support security camera<br>
> for the community pre-school.<br>
><br>
> The core is a UDM Pro router, feeding all Ubiquiti stuff.<br>
><br>
> And it has run totally steady.<br>
><br>
> Here's the rub: Now that the "Last Guy That Touched it" moved to<br>
> Florida, I'm getting multiple alerts per day to the effect of:<br>
><br>
> * Your primary internet Comcast Business was disconnected and has been<br>
> restored multiple times in last 24h. If this persists, please try<br>
> restarting your ISP Modem.<br>
> * Primary internet is experiencing high latency. Please restart the<br>
> modem or contact the ISP if this persists.<br>
><br>
> Aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaand, nobody complains. Occasionally,<br>
> I will see Zoom meetings from home where the church participants go<br>
> really fuzzy and blocky, like Zoom has downshifted their resolution.<br>
><br>
> Apparently it measures ping time to <a href="http://Ping.UI.Com" rel="noreferrer" target="_blank">Ping.UI.Com</a> to decide this.<br>
><br>
> The Unifi Console reports the Comcast Business router as providing<br>
> typical 14ms latency. With the occasional spike to 45ms.<br>
><br>
> When I ping that address from my Uverse internet from home, I'm seeing<br>
> consistently results from 7ms to 10ms.<br>
><br>
> I don't know whether to ask Ubiquiti about raising their thresholds, or<br>
> Nag Comcast about their performance. I guess I could ask Ubiquiti<br>
> precisely what does "Internet Disconnected" mean?<br>
><br>
> My personal experience with Business Comcast in the past has been.......<br>
> not impressive. Usually, a service call just makes it worse. Is<br>
> Comcast going to take my report from Ubiquiti seriously? Or tell me to<br>
> pound sand? What additional evidence need I present?<br>
><br>
> Yes, I could spend a quality hour in the furnace room, with a notebook<br>
> connected to the LAN side of the Comcast router, (the only way I can<br>
> talk to it) and see what I can see.<br>
><br>
> I suppose I could just call Comcast, and give up another hour of my life<br>
> to try and talk to someone with a clue.<br>
><br>
> regards,<br>
><br>
> Neal<br>
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<br>
-- <br>
Derek Atkins 617-623-3745<br>
<a href="mailto:derek@ihtfp.com" target="_blank">derek@ihtfp.com</a> <a href="http://www.ihtfp.com" rel="noreferrer" target="_blank">www.ihtfp.com</a><br>
Computer and Internet Security Consultant<br>
<br>
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</blockquote></div>