Help needed with intermittent internet

The Linksys is handling the "external routing," in terms of your question, although I think there is a little misunderstanding about this function. The Netgear is the cable mode, for sure, but it also "routes" our static public IP address to/from the Linksys, which I have configured for static IP address, NAT, and no DHCP. DHCP is handled by the Novell server.

Some confusion surrounds exactly what functions are provided by the Netgear, and I believe our problem is mostly one of semantics and how each of us thinks of "router" vs "modem." The Netgear is indeed a router, at least in terms of Comcast's system, but it's not playing that role in terms of the subscriber network. This has caused great problems for me in my conversations with Comcast, because my basic view is this:

- a "modem" is a device that converts/reconverts a particular type of carrier signal to a signal that can be used by computers and networking equipment

- a "router" is a device that specifies where network traffic goes

So, what is the Netgear doing? In my mind it's being a "modem," not a "router." However, in Comcast's world it's very much a router. Practically speaking, Comcast doesn't route internet traffic "to" the subscriber device (router, switch, NIC, etc) to which their equipment is attached. They route internet traffic "to" their device, which then "passes to" the subscriber device.

This is how I understand it. Of course, my understanding of all this is changing almost by the hour, so don't hesitate to shoot that one full of holes, too.

Yes.

My thoughts and words precisely to at least 2-3 of the Comcast support people. However, this view reflects a misunderstanding of how Comcast (and perhaps cable providers in general??) do things. With a business account using a *static* IP address, there is no such beast as a "plain old modem." Plain Old Modems are for residential and business accounts with a "dynamic" IP address.

In the Comcast system, there is no method of assigning a static IP address to a plain old modem.

And, what's even more frustrating, is that Comcast in my area offers exactly ONE device for business/static provisioning: The Netgear unit we have.

jm

A modem is a bridge. A bridge is normally used to connect two different kinds of physical networks. In this case, it is a bridge between the HFC network, and the Ethernet network. It operates at layer two of the OSI network. It doesn't open the IP packets; it only changes the physical medium over which they're carried.

A router can direct traffic to multiple devices, like the lay definition would infer. But it doesn't have to. A router, in terms of completer networking, is a device that works on layer three of the OSI model. It opens the IP packets, and inspects them. Based on that inspection, it can direct traffic to multiple devices, or it could do a number of other things.

In it's application here, it is primarily used to segregate the subscriber's network from the Comcast network. TCP/IP traffic using private IP addresses cannot travel between networks. Neither can transport or network protocols that aren't TCP/IP. The primary purpose of using a router at this point is segregation of networks, not direction of traffic. Forget the common dictionary definition of what a route is, or that the device happens to be named a router. Just because it's named a router doesn't mean it's directing traffic between multiple devices, and just because it isn't directing traffic between multiple devices doesn't mean it's not a router in networking terms.

You're using a layman's concept of what a router is. Remember we're talking networking here. When I say "router", I'm talking about a device that works on level 3 of the OSI model, and therefore is partially opening packets in order to decide what to do with them. I don't care if there's only one path in and out on each side. That's not relevant in networking terms.

It's mostly a business decision to use a combo device. They *can* assign a static IP address to a customer's equipment with just a modem. The modem's IP address, a 10.x.x.x address, is only used to manage the modem, and is not involved in how traffic gets to or through it. Before DOCSIS, IP wasn't even used to manage the modem, so modems didn't even have IP addresses. (The exception was the LanCity system, which could really be thought of as an early version of DOCSIS.)

The apparent reason why they use a combo device for business customers is that business customers often have more complex networks than home users, and the router ensures that the two networks are segregated -- and are segregated by a device that the customer can't accidentally take out of the picture. Essentially, they're afraid that the customer's complex, mission critical network is going to be operated by someone who doesn't understand the OSI model, and why it's essential to have a level

Then they need to get people who know how to manage it.

When you asked them about a "sleep mode", and they said that there was no such thing, they were overlooking the ability of the router to block IP services based on a schedule. Either they were having a cognitive disconnect, and didn't realize you were talking about the whole device, and not just the modem part of the combo, or they really don't know what control they have over their router.

At this point, my confidence that it's the router, not the modem, is high. You need to be talking to someone who not only knows the box is a combo device, but understands the difference between the modem and the router parts, and what they each do. And I'm starting to get the feeling (based on what you said earlier) that you're not clear about what a router is as well. Perhaps you don't normally need to know, but whoever you talk to at Comcast better know, and in this case you need to know so you can tell whether they know. In other words, someone needs to understand that a router really does.

(Hint: "A 'router' is a device that specifies where network traffic goes," as said earlier.)

You're not assigning the IP to the modem, but to the router connected to the modem. In your case it's all in one Netgear box. Many people have static IPs to their networks (1 or more) - they just pay a few $/mo for the static IP(s) and deal with it at the router.

There's no reason for this. Many ISPs will let you convert from a dynamic IP to a static IP for $1/mo. It shouldn't make any difference to them what kind of modem you're using as long as it's on their list of supported devices (and most ISPs will support several modems). There's something really inept going on here IMO. It's just a matter of config'ing your router to the static IP.

There's a whole bunch up there that my ego would like to clarify, but it likely would detract from the target. I do understand what a router does. I do understand the OSI model. My attempts to generalize and present the various miscommunications between myself and a room full of Comcast support people over the past 4 weeks misrepresented the situation. That a router operates at layer 3 is a fact. That it does much more than "route" traffic also is a fact. However, I'm having trouble seeing the pertinence of this information, in the context of your theory concerning possible cause. If I'm interpreting your comments correctly, you think the router might be blocking IP traffic according to a schedule. If that's so, then would we see the internet "down" specific times of day? Should it be predictably recurring? Could there be other times of the day when the internet is intermittent? Finally, would a reset of the Netgear "fix" this type of problem?

jm

Well, here's where we are:

Comcast has stated that the modem is not going down, and there's nothing in the modem logs to indicate a problem.

You've isolated your LAN from the Netgear box.

That narrows things down to the router in the Netgear box.

You've implied that this happens every night, over night. That would seem to indicate a regularly scheduled event.

So possible issues include: - The router is configured wrong, possibly blocking on a schedule. - The router has some other problem. - The router, and the other two also, are all from the same batch, and are all defective. - You really didn't isolate your LAN from the Netgear. - Comcast isn't being honest about the modem not having a problem.

That's a pretty short list, but it could get longer if one of the last two items on it are where the problem is. But assuming that you did isolate the LAN from the Netgear box, and assuming that Comcast is correct that there aren't any problems up to and including the modem that's in the Netgear box, then we're down to the something with the router in the Netgear box.

So assuming that isolation troubleshooting has been properly done, and the results have been correctly reported, it's now time to focus on that router. I'm suggesting the blocking schedule because the context of your reports of your conversations with Comcast infer that they aren't aware of a way that the Netgear box can shut-down sometime overnight, and your reports on when the problem happens, for the most part, point towards the same timeframe each day. But that's just one example of what it could be, and something that I'd look at first in the router configuration.

My point is that isolation troubleshooting has narrowed us down to the router. The symptoms reported are not inconsistent with a router problem. (They were inconsistent with a bridge problem.)

What else can be done?

You can physically disconnect the LAN instead of just disabling the NIC. That would confirm that you have isolated the problem to someplace outside your LAN. And Comcast can recheck the modem logs, and recheck the RF signal to the modem. If everyone re-does, and confirms the steps they've taken to isolate the problem, then we're right back at the router. And so far, I've seen absolutely zip on the router configuration. The only thing we know is that three different physical routers have been in place during the course of this problem.

Speaking of things I haven't seen addressed, a number of times I've asked if they only replaced the combo box, or if they also replaced the power brick for it as well. And I've also asked about what other electrical equipment might be on the same circuit. Even if you can't get into the router to check the configuration, you should be able to make sure that it's getting clean power.

I'm not saying I'm locked into the blocking schedule theory. But I am saying that if all the information that has been offered is correct, and all the methodology has been sound, then we have isolated the problem to that Netgear router packed in the same box as the modem. And despite replacing the combo box twice already, the problem is still there.

So what else can it be? Either you need to go back and re-do the isolation troubleshooting again, and see if you wind-up someplace else, or the problem is in the router. And they symptoms are not inconsistent with something that can happen with a router.

Where else can we go with this?

To a tech that can configure something other than a Netgear combo modem. ;)

To a tech that can get a line tech out to set up the amps feeding the modem.

To a tech that understands that just because a modem is "in spec" doesn't mean it will work properly.

To a tech that will actually troubleshoot and not just swap out a perfectly good modem.

I could not agree more. After another week watching this thing go down every single night and having to reset it every single morning, I'm convinced there is a signal problem to the modem that could be identified if a competent tech would perform some real troubleshooting. But the tech they keep sending does not qualify. In all seriousness, he appears to have a learning disability. I'm not being mean. I'm just stating the truth. I feel sorry for him, really, but the fact remains that Comcast is not bringing high-level resources to bear on this problem.

jm

You mean they keep sending the same guy? I'm sorry to say this, but you're going to have to contact your sales rep (since this is a commercial account, you'll have a sales rep), and demand they escalate the issue to the local supervisor. It is unacceptable for them to continue to send the same guy out time and time again without resolution. Make sure you make your rep aware of all that has transpired.