UPS for router + modem

D

Donovan

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Now that my connection actually seems stable (it's been "up" for 4 days now.. which is truly amazing considering how bad my signal/connection was before), and it's working properly (been getting proper speeds on a 128kbps package for a few weeks now), I'd like to invest in a UPS for my little router and modem.

I know the modem has a battery in it, and I assume that the power consumed by the router is very negilgable - so what UPS would be the least overkill? How long would the UPS maintain the backup power on such small devices?

Thank you!
 
The modem power supply is rated at 5 watts. Check if your router has a power rating (on the router itself, or on the external power pack if it has one). I would expect a small router to draw max 20 W. (Total for modem and router = 25 W)

In my experience, I usually work on a PC drawing 100 to 150 W for UPS calculations. If a ups states it will run a PC for 15 minute (most cheap ones are in this region), then it would run the above Modem + router for 1 hour...

(EDIT): Beware, some UPS's will not work properly with low load. Check with the supplier!

Do you have your PC's on UPS?

If so, why not just hang it off the existing UPS?
If not, why would you want the modem and router powered if none of your PC's are on?


Headend
<font size="1"><b>Tower:</b> Mintek (82) - <b>Signal:</b> 25% (Poynting Grid Antenna) - <b>Firmware:</b> 5.0.1.62/A2 - <b>256k</b> package
<b>SNL:</b> 9dBm <b>BER:</b> 71% <b>RSCP:</b> -77dBm <b>ISCP:</b> -88dBm - Smoothwall and PPPoE</font id="size1">
 
I got one of those plugs that go into the back of the PC's powersupply (but the female plug) to solder onto a two or three plug extention cord. So I can plug it into the back of any UPS and plug the modem and switch into that.

Not much of an issue with adsl or sentech, but it did make sense with dial-up and R7-weekend to prevent the modem from going down, even if the PCs does. Gateway/firewall was an old P-1 notebook...

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koffiejunkie
 
The router and modem are nicely tucked away in the top of a cupboard in a central location where the wireless signal reaches most areas of the property... my iBook has a battery in it so it will always have power.

Some other stuff is on UPS, but it's too far away from the router to connect it that way.
 
You can probably get away with a cheap 600VA and it should run for over an hour (maybe two). I have my server box (Pentium III, no monitor), ISDN box, fax machine and hub running off a 600VA and it runs for about 45 minutes.
 
I've got one of those cheap UPS soltions - cost me R600 and it came in very useful in my old rented cottage. It has two power outputs. Gives me about 5 minutes with monitor on and about 25 with monitor off.

Now I've got sentech, my current solution is :-

From first outlet on UPS I attach my Smoothwall firewall/router (no monitor attached). Then from that PSU I run a male to female power cable to my main PC PSU. Finally, from the second outlet on the UPS I connect my main monitor which is only switched on when I'm working at the computer.

I've left my modem running on battery power for over 45 minutes - far longer than my UPS will handle. There's no need to hook up the modem unless you have a UPS capable of running for longer than the modem battery. So long as your router is hooked up, your fine.

So basically, when I'm away from home or sleeping, my power can go off for 25 minutes and I stay connected.

Pretty cool - it's come in handy once or twice.

BTW, with smoothwall, you can also set it to reboot if your modem disconnects - after 5 minutes of no activity, smoothwall reboots and tries to connect again. That is so damn useful for large downloads.
 
bb_matt, why do you have to reboot Smoothwall? I haven't tried Smoothwall in ages (downloading as we speak), but in IP-COP you can set your connection to be "persistent" so it will keep trying to connect untill it has success or until it has reached the number of retries you specified.

Yeah, I know the ISP might find that to be abusive, but if they promise an "always-up" connection they shouldn't complain if my firewall takes offence :-)

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koffiejunkie
 
Koffie, unfortunately there is a bug in the PPPoE 'bit' on smoothwall that has broken persistent PPPoE connections. I have solved this by adding a CRON script to try and connect every minute. If the connection is currently up, the connect gets ignored. If it's down, it reconnects. I was driven to this a couple of weeks ago when I was getting disconnected every hour.

Headend
<font size="1"><b>Tower:</b> Mintek (82) - <b>Signal:</b> 25% (Poynting Grid Antenna) - <b>Firmware:</b> 5.0.1.62/A2 - <b>256k</b> package
<b>SNL:</b> 9dBm <b>BER:</b> 71% <b>RSCP:</b> -77dBm <b>ISCP:</b> -88dBm - Smoothwall and PPPoE</font id="size1">
 
Oh, I see. Does Smoothwall not release hotfixes like IPCOP? Sorry, I haven't really had time to read the docs.

Nothing like something that needs to get often to force us to hone our scripting skills....

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koffiejunkie
 
They do, but usually only for vulnerabilities. It's been on the known bugs list for ages, but I guess most broadband providers don't drop connections they way our's does [;)]
 
They should still fix it - it's pretty dumb to have to reboot your firewall (reboot linux, for that matter, that's just wrong :-) everytime your connection drop. That requires user intervention, which defeats the point of having your firewall manage a connection.

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koffiejunkie
 
koffiejunkie, you don't need to reboot smoothwall when the connection drops. Just need to add one line to your cron file and the longest the link is down is 1 minute...
 
Sure enough. My point is it's still a hack because of a really stupid bug (considering the application). When I get time to check out smoothwall, I'll compare it's config files with IPCop's and see if I can find a fix.

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koffiejunkie
 
Headend

Could you mail me directions on how to change the cron file. You'll need to explain it in detail as I was born with a mouse in my hand. :)

MyWireless 128, Tower: 82, Signal: 13%, SNL: 6, ber: 42%, node: 3
 
type <b>root</b> on at the login prompt + your root password.
type <b>cd /etc</b>
type <b>ls</b> and check there is a file named 'crontab' in the directory. ls = dir in DOS.
type <b>vi crontab</b>
Use the down arrow to scroll to the bottom of the file.
type <b>i</b> to enter insert mode.
type a comment and hit 'enter' to go to the next line. Mine is <b># Redial every minute</b>
type <b>*/1 * * * * root /etc/ppp/ppp-on &gt; /dev/null</b>
press 'esc' to get out of insert mode.
type <b>:wq</b> to write and quit vi.

That should be it.

To test, I get my modem to loose signal - cover the modem with a can, or unplug your external antenna if you have one. Once the modem drops the connection, wait a couple of minutes to check it reconnects.

Goodluck!

Headend
<font size="1"><b>Tower:</b> Mintek (82) - <b>Signal:</b> 25% (Poynting Grid Antenna) - <b>Firmware:</b> 5.0.1.62/A2 - <b>256k</b> package
<b>SNL:</b> 9dBm <b>BER:</b> 71% <b>RSCP:</b> -77dBm <b>ISCP:</b> -88dBm - Smoothwall and PPPoE</font id="size1">
 
Just an aside, some linux renditions don't like a raw edit of crontab (not sure about smoothwall) .. When possible use "crontab -e" ... to edit the crontab file.
 
Thanks Headend. Will give it a try later when I finish work... say around 12pm tonight *g*

MyWireless 128, Tower: 82, Signal: 13%, SNL: 6, ber: 42%, node: 3
 
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