Debugging My ADSL
My ADSL hasn't been perfect at my home for a year or so now. Basically it looses the connection. Sometimes once a week, sometimes it's 4 or five times a day. I've been too lazy to sort it out because it just seemed easier to reboot the modem, wait 30 seconds and carry on with my life. I've had ADSL nightmares before where I spent hours on hold waiting to talk to a support serf and I haven't been keen to repeat this.
A friend of mine coincidentally asked me if I knew anything about a provider he was thinking of joining. He started to bemoan his provider and the ancient wiring in his london flat. So I replied and tried not to think about my problems. As often happens I couldn't stop thinking of my own problems! I stumbled upon RouterStats. It's a cool little win32 app that basically knows how to read you routers stats page and display a little graph. I ran it on my mac using VMWare Fusion and sure enough it showed my modems 'noise ratio' getting lower and lower toward the magic 6db mark where most routers just give up and drop their ADSL connection.
A this point I decided that I couldn't be bothered to run this App (and a resident copy of windows JUST so I could look at my router stats. So I turned to python to scrape my router page
#script to scrape the stats from a Netgear DG834GT import urllib2 import re from BeautifulSoup import BeautifulSoup from time import sleep from datetime import datetime base_path="http://192.168.1.1/" monitor_page='stattbl.htm' username='admin' password = 'password' top_level_url = base_path #register an opener with urllib2 which knows how to respond to basic #authentication requests from a webserver password_mgr = urllib2.HTTPPasswordMgrWithDefaultRealm() password_mgr.add_password(None, top_level_url, username, password) handler = urllib2.HTTPBasicAuthHandler(password_mgr) opener = urllib2.build_opener(handler) urllib2.install_opener(opener) #re to extract the number section from a string in the form xxx.xx db dbre=re.compile(r"(?P<num>[\d\.]+)\s*db") #for ever, ask for the stats page, extract the data and print it, #it's not pretty code but I am scraping a bloody router stats #page so WHO CARES while True: response = urllib2.urlopen(base_path+monitor_page) html= response.read() soup = BeautifulSoup(html) tables= soup.body.table.findAll('table') tds = tables[0].findAll('td') tx = tds[13].span.contents[0] rx = tds[14].span.contents[0] def extract(node): s =dbre.match(node).group('num') return float(s) tds = tables[1].findAll('td') att_down = extract(tds[7].span.contents[0]) att_up = extract(tds[8].span.contents[0]) nm_down = extract(tds[10].span.contents[0]) nm_up = extract(tds[11].span.contents[0]) now = datetime.now() print now.strftime("%H:%M:%S"), "atd:", att_down, "atu:",\ att_up, "nd:", nm_down, "nu:", nm_up, "rx:", rx, "tx:", tx sleep(5)
Every five seconds this prints out the stats for my router
13:44:18 atd: 21.0 atu: 22.0 nd: 13.0 nu: 26.0 rx: 10138 tx: 4138 13:44:23 atd: 21.0 atu: 22.0 nd: 13.0 nu: 26.0 rx: 10138 tx: 4138 13:44:29 atd: 21.0 atu: 22.0 nd: 13.0 nu: 26.0 rx: 10137 tx: 4138 13:44:34 atd: 21.0 atu: 22.0 nd: 13.0 nu: 26.0 rx: 10136 tx: 4137 13:44:39 atd: 21.0 atu: 22.0 nd: 13.0 nu: 26.0 rx: 10135 tx: 4137 13:44:44 atd: 21.0 atu: 22.0 nd: 13.0 nu: 26.0 rx: 10135 tx: 4137 13:44:50 atd: 21.0 atu: 22.0 nd: 13.0 nu: 26.0 rx: 10134 tx: 4136 13:44:55 atd: 21.0 atu: 22.0 nd: 13.0 nu: 26.0 rx: 10133 tx: 4136 13:45:00 atd: 21.0 atu: 22.0 nd: 13.0 nu: 26.0 rx: 10132 tx: 4136 13:45:05 atd: 21.0 atu: 22.0 nd: 13.0 nu: 26.0 rx: 10131 tx: 4135
Well I left this running and guess what? When the phone rang my noise ratio dropped... and if it was already low my router dropped the connection. If I even picked up my phone the noise ratio dropped. After poking around with the wiring it turns out one of the phones in the house didn't have an ADSL filter so it was spewing noise on to the telephone line in the frequency range ADSL uses! Doh. Without the filter my best noise ratio was 9db, with the filter it never drops below 12db.