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darky4

join:2011-04-23

[Config] CISCO 857 Drops Internet Access when idle

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Hi!

I Love my CISCO 857 it's a wonderful piece of kit, but theres a problem. I can't leave it unattended!

It's only my second piece of CISCO kit but I'm hooked and been self teaching pretty successfully over the last few months taking in loads of advice from everybody. But one problem is still causing me major problems.

If I leave it for a few hours/overnight etc when I come back to use the internet the connection is down. Browser complains of DNS issues however it shows as connected. Telnet into the router you find no obvious issues, various debugging doesn't show anything.

I think it could be Layer 2 issue as I can't ping gateway though. It could also be a config issue as I'm by no means an expert. It could also be the face that I live in the sticks about 6-7km from the exchange, basically it could be anything! ISP is UK O2 Broadband.

Please help me as I love my router (o:

Many Thanks

I have enclosed all the usual results from obvious show commands which i administered when i found it had stopped again.

nosx

join:2004-12-27
00000
kudos:5
My advice is to setup an EEM applet like this:
ip sla 98
 http get http://www.google.com name-server 4.2.2.1
ip sla schedule 98 life forever start-time now
track 101 rtr 98 reachability
 delay down 5 up 10
event manager applet EEM_HTTPGET_GOOGLE_DOWN 
 event track 101 state down
 action 4 syslog priority errors msg "cant get google.com! ISP is broken!"
event manager applet EEM_HTTPGET_GOOGLE_UP 
 event track 101 state up
 action 4 syslog priority errors msg "cant get google.com! ISP is fixed!"
!
 
And configure it to run forever. You will be able to log into the router and perform a 'show log' command, and look for periods where your router could not reach google.

This will identify where the issue is. Once you narrow it down (LAN problem / WAN problem) better guesses can be made about the cause of the problem. At the very least it will keep your connection active so that your ISP's DSLAM doesnt trigger some kind of inactivity timeout.

flq06

join:2009-08-06
Verdun, QC
reply to darky4
May I suggest you to check your Dialer interface configuration. Make sure to remove "dialer-group x" if present.

This command is DDR related and it tells the router to Dial only when there is interesting traffic defined by "dialer-list x". Maybe you don't even have a dialer-list but you have the dialer-group? That would be the most killing scenario. IOS will timeout the idle-timeout (default to 2 min) at any given time. I had the issue myself, some IOS won't even disconnect you. they don't behave the same way. On my side the problem only started after an IOS upgrade and I had to ran debugs for a few days before it flapped again and I could literally see something like "DDR Idle timeout exceeded, disconnecting Dialer"

You don't want a DDR but a "always-on" connection.


OVERKILL

join:2010-04-05
Peterborough, ON
said by flq06:

May I suggest you to check your Dialer interface configuration. Make sure to remove "dialer-group x" if present.

This command is DDR related and it tells the router to Dial only when there is interesting traffic defined by "dialer-list x". Maybe you don't even have a dialer-list but you have the dialer-group? That would be the most killing scenario. IOS will timeout the idle-timeout (default to 2 min) at any given time. I had the issue myself, some IOS won't even disconnect you. they don't behave the same way. On my side the problem only started after an IOS upgrade and I had to ran debugs for a few days before it flapped again and I could literally see something like "DDR Idle timeout exceeded, disconnecting Dialer"

You don't want a DDR but a "always-on" connection.

I regularly use dialer groups and have never experienced this issue. This is with 857, 877 and 867 model routers. As well as the 1841.

darky4

join:2011-04-23
reply to darky4
Thank You nosx!

I don't really need to track events as I was just happy to have a connection that stayed up! Which it has ever since I added the SLA, so not only have you solved the issue but have enlightened me to a very useful feature of IOS.... Many Thanks (o:

PS> Thanks for the other surggestions folks but I don't use dialer groups as its PPPoATM.

bigsy

join:2001-07-18
ireland
kudos:1
said by darky4:

Thanks for the other surggestions folks but I don't use dialer groups as its PPPoATM.

The problem is that it is not PPPoA, otherwise you should be able to use some variation of dialer lists and the 'dialer persistent' command to keep your connection alive.

You're on a service that runs 'ETHoA' or 'IPoA' and requires the router set to RFC1483 bridged.


Covenant
Premium,MVM
join:2003-07-01
England
The other issue is that you are too far from the exchange on the DSLAM profile you are on....

You are what BT Openreach would call a Long Line issue:

DFE BOM:         DFE3.0 Annex A (1)
Capacity Used:   90%                             99%
Noise Margin:     3.5 dB                          9.0 dB
Output Power:    18.0 dBm                        12.0 dBm
Attenuation:     45.0 dB                         25.0 dB
Defect Status:   None                            None
 

See the DS noise margin, it is a 3.5... ideally it should be at 6.5 however using rate adaptive ADSL, BT Openreach have stretched the limits of the SNR right down to 4.0 to 4.5.

Another thing to note is since you reloaded your router 1 day and 18 hours ago, your router's ATM interface reset at least 7 times as you have 8 activations:

Activations:     8
 

If you still suffer instability, you can ask O2 to put you on a lower speed profile which will bump up your SNR but not by much.

However I am glad that you are seeing some kind of stability now.

--
A word to the wise ain't necessary, it's the stupid ones who need the advice!