Small Business Network Troubleshooting Steps

[mowgli]

Hi everyone,

Here's the setup for my small business network, which I think is pretty simple:

[Network Devices][......][Patch Panel][Two 24-port TP-LINK Unmanaged switches][Frontier ActionTec F2250 VDSL router/modem]

There are approximately 35 devices connected to the 2 TP-Link switches. My Frontier DSL speed is 15mbps/2mbps. I believe most of our network traffic is in the INTRAnet, and the speed is sufficient for our INTERnet usage.

Every 2-3 weeks, all the computers & devices on my network lose internet connectivity. It usually takes one to four modem restarts to bring all devices back up. It's affecting productivity, not to mention getting pretty annoying.

How should I go about troubleshooting this issue? I'm suspecting it's the router/modem that's not able to keep up with so many devices connected to it. If so, is there another VDSL modem you'd recommend for my setup?

Anything else I should be looking at? I appreciate any help!

 

[Fardringle]

If the modem/router combo is having problems that frequently, have your ISP replace it. If possible, have them give you JUST a modem, and then use your own router between the modem and the switches.

 

[AnonymouseUser]

If the modem/router combo is having problems that frequently, have your ISP replace it. If possible, have them give you JUST a modem, and then use your own router between the modem and the switches.

I agree with Fardringle, unless you pay a monthly rental fee for the modem. In that case buy your own modem and router. I hate modem/router combos for several reasons, especially for security. Get a secure router to protect that network.

 

[Gryz]

What I learned on this forum:
1) networking is magic, nobody really knows what is going on in a network. And there are no ways to look.
2) the only approach to any problem is: replace hardware.
3) a router with an DSL-interface or a cable-interface inside is totally different from a router with an ethernet-interface or wifi-interface inside.

Awesome !

 

[AnonymouseUser]

What I learned on this forum:

3) a router with an DSL-interface or a cable-interface inside is totally different from a router with an ethernet-interface or wifi-interface inside.

Awesome !

Aren't you a "networking guy," though? If so, you should know that a router with a DSL- or cable-interface also has an ethernet-interface and/or a wifi-interface. That's why it's called a router. Sorry to hear about your learning disabilities. :'(

Pro tip just for you: that screwdriver blade on you're 10-in-1 pocket knife is not as good as a dedicated screwdriver. If I ever see you struggling to remove a screw and recommend using a screwdriver instead of your knife, it's not because I don't understand how screws work, it's because I do understand how pocket knives work.

BTW, I just looked up OP's router. Why am I not surprised?

 

[mxnerd]

1. Check phone cable. It could be too old or bad, replace it.

2. See if someone is doing torrent download, it could cause modem to disconnect.

3. It could be modem router itself, some bad reviews on Amazon. http://www.amazon.com/Actiontec-DSL-Modem-F2250/dp/B00JWUOWDU

 

[JackMDS]

What I learned on this forum:
1) networking is magic, nobody really knows what is going on in a network. And there are no ways to look.

This is absolutely true when it comes to Internet as oppose to Local Network.

Notice that the OP While his Topic states - "Small Business Network Troubleshooting ", did not realy complain about his Local Network but rather "Cry" that his Internet goes down periodically.

There No other industry in the world like the ISP industry that never disclosed exactly what they do, trying to squeeze every $ that they can and provide the least service for it.

You stated "Magic" while it is really "Black Magic".

As per wiki: " Black magic or dark magic has traditionally referred to the use of supernatural powers or magic for evil and selfish purposes".

 

[Railgun]

Aren't you a "networking guy," though? If so, you should know that a router with a DSL- or cable-interface also has an ethernet-interface and/or a wifi-interface. That's why it's called a router. Sorry to hear about your learning disabilities. :'(

Pro tip just for you: that screwdriver blade on you're 10-in-1 pocket knife is not as good as a dedicated screwdriver. If I ever see you struggling to remove a screw and recommend using a screwdriver instead of your knife, it's not because I don't understand how screws work, it's because I do understand how pocket knives work.

BTW, I just looked up OP's router. Why am I not surprised?

Difference in physical media is NOT why it's called a router.

 

[AnonymouseUser]

Difference in physical media is NOT why it's called a router.

Of course not, but you won't have a router without those ports.

 

[Gryz]

Aren't you a "networking guy," though? If so, you should know that a router with a DSL- or cable-interface also has an ethernet-interface and/or a wifi-interface. That's why it's called a router.

A router is a layer-3 device, with two or more interfaces. Those interfaces can be any kind of layer-2 technology. DSL or cable, ethernet or WiFi, serial line, dialin-modem, ISDN, SDH or Sonet, Frame-Relay or ATM. And the majority of router have the majority of their layer-2 interfaces integrated into themselves. And that is never a problem.

Only when we talk about DSL and cable, some people have separate routers and layer-2 interface (called a modem in the case of DSL and cable). And only in the US. In the rest of the world, DSL-routers and cable-routers have their layer-2 interfaces integrated.

Do you complain that your router has Ethernet inside ? It could be a separate device ! (Google for Ethernet transceiver). Do you want your WiFi to be a separate device ? Or can it be integrated in your desktop or laptop ? Or on the motherboard even ? Do you enjoy two powersupplies ? Two management interfaces ?

Really, there is no good logical reason to separate router and modem.
Your situation in the US is just because of historical reasons.

Pro tip just for you: that screwdriver blade on you're 10-in-1 pocket knife is not as good as a dedicated screwdriver. If I ever see you struggling to remove a screw and recommend using a screwdriver instead of your knife, it's not because I don't understand how screws work, it's because I do understand how pocket knives work.

So you carry a separate phone for calling people, separate electronic agenda device, and a laptop for browsing the Internet ?
People want cheap small easy tools. And the less tools, and the more functional, the better.

BTW, I just looked up OP's router. Why am I not surprised?

If it is junk, it is junk.
But that is not because a separate router and modem are better.

Not sure you can conclude that from 6 responses on an Amazon page. Not one of them has technical details.

 

[Gryz]

This is absolutely true when it comes to Internet as oppose to Local Network.

I agree that troubleshooting your connectivity issues is not an easy task.

Notice that the OP While his Topic states - "Small Business Network Troubleshooting ", did not realy complain about his Local Network but rather "Cry" that his Internet goes down periodically.

To be precise, he complained that his devices lose internet connectivity. If you wanna go into details, that does not mean "his internet goes down". Most likely, but without troubleshooting, you won't know. It might be his local router doesn't forward packets anymore. It might be ARP-tables getting messed up. It might be a DNS problem. So many things can go wrong. Just stating "replace the router" is almost like throwing away your car because you ran out of gas.

There No other industry in the world like the ISP industry that never disclosed exactly what they do, trying to squeeze every $ that they can and provide the least service for it.

That's capitalism for you.
Our ISPs are a bit like that too, but in the end our old ex-commie PTT does make sure your DSL will work again.

You stated "Magic" while it is really "Black Magic".

As per wiki: " Black magic or dark magic has traditionally referred to the use of supernatural powers or magic for evil and selfish purposes".

Yep, you are probably right.
I was thinking of a quote from Arthur C. Clark.

Any sufficiently advanced technology is indistinguishable from magic.

 

[Gryz]

How should I go about troubleshooting this issue? I'm suspecting it's the router/modem that's not able to keep up with so many devices connected to it. If so, is there another VDSL modem you'd recommend for my setup?

Anything else I should be looking at? I appreciate any help!

Some general remarks that might help.

*) Most routers have a web-interface for management. Figure out what the ip-address of your default-gateway is. Type that in your browser. You might need the admin-username and password. If you haven't touched that, it should be in the manual or on a webpage somewhere.

*) Via the webpage of your router you can actually see the details of the state of your router. This includes the state of your DSL-interface. You can see if it is up, how long it has been up, whether it is training, how often it is training, etc. (Training is trying to set up a connection between your router and the router/DSLAM of your ISP).

Note, if you had a separate router and modem, you could probably not look at these things.

Try all the pages on your router and see if there is anything interesting. E.g. see if DHCP leases are good. See if there is any traffic going through the box, into the box, out the box.

*) Text-based utilities are best for trouble shooting. If you have a Linux/Unix box, it probably has more tools than Windows has. In Windows, start a dosbox/command.com and try to get familiar with these:

1) netstat -rn
This shows the routing table. See if there is default route (denoted as 0/0 or 0.0.0.0/0 or 0.0.0.0/0.0.0.0). If so, what is the default-gateway ? Can you ping the default-gateway ? If not, do you have an arp entry for it ?
2) arp -a
This shows the arp-cache. For every ip-address on your local network you are talking to, there should be an arp entry. In normal operations, there should be an arp entry for your default-gateway
3) look at DNS. If you can't reach websites on the Internet, is that just when you use names, or also when you use IP-addresses ? On Linux you have tools like host and nslookup to check if DNS is working. Not sure how to do that on Windows.
4) DHCP.
This is the protocol that hands out IP-addresses. When you have problems, do your devices still have valid ip-addresses ? Can they ping each other (all on the local network). On the webpage of your router you should be able to see DHCP-status.
5) ping.
Mostly useful to ping the end-destination (a website on the net), or your local default-gateway. In any case, you should be able to ping that. if you can't ping your default-gateway, the problem is local, and not your internet connection.
6) tracert (or traceroute on linux).
Read the manpage, or something on the Internet. Can be helpful if the problem is further away towards the Internet, not on your local network. If that is the case, this tool can help determine where the problem, but not fix it.
7) Last resort: a packet sniffer. Check out WireShark. Free and powerful. You can see what is going on on your network in detail. Probably your last resort, as it can take quite a while to get familiar with. If you really know nothing about networking and TCP/IP this is probably useless.

*) Try these tools when everything is working. So you know how things look when there is no problem. When a problem does arise, you might be able to see the difference. If you never looked at normal behaviour, it gets very hard to spot the problem.

With these tools I would do something like this:
there is a problem ->
see if you can login to the webpage of the router ->
if not, check the local network. ping the def-gw, look at arp, look at netstat -rn
if you can, check the status of the DSL interface ->
is it connected ? does it have a lot of errors ? is it flapping ? when was the last status change ? are the traffic counters increasing ?

Good luck.

 

[AnonymouseUser]

Do you want your WiFi to be a separate device ?

Actually yes I do. My next wireless purchase will likely be a Ubiquiti UAP, with or without an Edgerouter as I've grown tired of consumer grade equipment. My modem will remain dedicated. If any one component quits working I can replace just the one component.

Do you enjoy two powersupplies ?

No, but I do expect to have full control over my devices, with full configuration options. I have yet to find a modem/router combo that gives me that control.

Two management interfaces ?

Yes. They serve different functions, and should have different interfaces.

Really, there is no good logical reason to separate router and modem.

Actually, there are really good reasons to separate them.

• For one, they simply cannot handle the same number of connections as dedicated routers as the modem and router share an underpowered CPU.
• They also often come with insecure settings by default (Comcast is one of the largest ISPs in the US).
• There are many that have backdoors deliberately installed in them.
• At least in the US, ISPs often charge a monthly fee, as much as $10. Buying your own devices will save you a lot of money over time.
• Want VPN access? Not happening with most (if not all) combo devices.

My own experiences with modem/router combos include:

• Motorola SBG6580 - not being able to set the LAN IP to 10.0.0.0/24, so I had a choice of reconfiguring clients to use new settings, or continue to use a non-crippled (eg, dedicated) router. I chose the latter. I was also able to place the router outside of the closet the modem was in for better wireless range.
• A fellow AT forums user had issues with her (UK/BT) internet when her roommate used Netflix. I logged into her modem/router combo to setup QoS but of course it's a crippled modem/router combo so it didn't have those QoS settings. I discoverd her 2.4GHz and 5GHz networks shared the exact same SSID and password (default ISP settings), so she had no way of knowing which she was connecting to. After changing the 5GHz SSID she connected to the 5GHz network and amazingly got double her previous max speed, even with her roommate still using Netflix. I also fixed her 2.4GHz network so it could do 300mbps instead of 144mbps. She has no more issues while her roommate uses Netflix.

So you carry a separate phone for calling people, separate electronic agenda device, and a laptop for browsing the Internet ?
People want cheap small easy tools. And the less tools, and the more functional, the better.

No. In those cases one function does not cripple another, so it's not a problem, but it rarely is "better" to use a phone than a laptop when browsing the internet.

Note, if you had a separate router and modem, you could probably not look at these things.

You most certainly can. My primary router is 192.168.1.200 and my modem is 192.168.100.1, and I have no problem connecting to the web interface for the modem through the router. I've also changed the password on the modem from default.

Some general remarks that might help.

Well if Fardringle and I didn't convince mowgli to replace his router, you most certainly did.