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ADSL2 Line Utilization causes ping to fail

Posted on 2009-05-13
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Last Modified: 2013-12-14
Hi, I've got an ADSL2 Line with a CISCO 877 configured.

I started pinging certain IP addresses every minute to see if there's a network issue as sometimes there will be drop outs.

Meaning, the pings will fail for a good minute or so.

I called up the provider explaining this and they tell me that the network is over-utilized. CISCO Web admin shows that the line is 100% utilized.

The provider says that the uplink is causing the problem and is peaking at 650K (theoretically there should be like 1MBps uplink and 22MBps downlink) and unless I do something over at my end on the LAN, there's nothing much they can do.


Network is running 2 different subnet, VLAN-ed at the CISCO level, having 10 odd clients each. Each VLAN has 1 microsoft SBS server. One LAN runs Exchange Server as well as a POSTFIX linus mail server, altogether about 10 internal email accounts. External people access the Postfix machine via POP3 and IMAP, total of 30 odd accounts.

Question I've got is
1. How can I throttle bandwidth without investing too much $
2. Is this sort of network behaviour weird? Network should not drop the ping, instead the latency should be higher.

any suggestions much appreciated.
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Question by:binele
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Expert Comment

by:blue-screen
ID: 24375870
1) Look up "MQC" on the Cisco web site (Modular QoS CLI).  You want to set up traffic shaping for outbound traffic, limiting the speed to your committed information rate.

2) It is normal for pings to be lost on overutilized networks.  Networks relieve congestion by dropping packets, and Ping packets get dropped like any other.  You can control you link congestion with traffic shaping, but if the provider drops packets before they reach the core of the network you can only control that by buying  a more expensive tier of service or picking a new ISP.

All ISPs oversubscribe their access links, from 10:1 to 100:1.  If you are sharing a link with 3 or 4 dorks running bittorrent 24x7, your performance will suffer.  Usually, "business class" service will get you into a better oversubscription tier, and away from the bottom dwellers that clog up consumer internet.
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Author Comment

by:binele
ID: 24381099
Hi Blue-screen,

thanks for the info.

Have tried to understand what MQC is from the Cisco web site but it looks a bit too technical for me at the moment.

Would it be possible to guide me into doing this? The QOS module is not installed on my CISCO router it seems.
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Expert Comment

by:blue-screen
ID: 24381172
Do you have the web interface (SDM) installed?  The web interface makes it easier.
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Author Comment

by:binele
ID: 24392766
Yup. I mainly use the SDM to access it.

Was just reading up on how to install the QOS for my IOS software

Can you please advise how to go about doing this? I'm lost at CISCO web site.

thanks a million
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Expert Comment

by:blue-screen
ID: 24397013
Maybe try
https://cisco.hosted.jivesoftware.com/docs/DOC-1574

In this case, what really mattes is the TOTAL BANDWIDTH, you can set voice and business critical to whatever.  The traffic shaping, which is a side effect of setting QoS, is what you want.

Also a qiock summary of how to do it on the command line:
http://slaptijack.com/networking/easy-traffic-shaping-in-cisco-ios/
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Author Comment

by:binele
ID: 24432568
Hi, thanks for the comment. I've taken a look at the video on line, looks pretty easy.

The QOS seems to be disabled on my router. Here's a couple of screenshots. Can you advise where I can get the QOS module
cisco1.png
cisco2.png
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Author Comment

by:binele
ID: 24432647
Just got thru to the Cisco Feature Navigator for the required feature.

There's a lot of them. Can you advise how best to filter thru?

My router is a cisco 877-M
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Author Comment

by:binele
ID: 24432690
Just so I don't overwrite everything and lose all the configurations during the upgrade ... thanks
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blue-screen earned 500 total points
ID: 24432704
You can use the Cisco feature Navigator:
http://tools.cisco.com/ITDIT/CFN/jsp/index.jsp

Look for Modular QoS CLI

Seems that it SHOULD be  there, as of 12.5(11)XJ4, and can't see why it wouldn't work.  You can upgrade to the latest 12.4T software if you have a service contract and see if that helps.
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Author Comment

by:binele
ID: 24533171
Hi tried best to figure this out, there's too many combinations and I don't think I have a service contract. How best to approach this?
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Expert Comment

by:blue-screen
ID: 24533225
If you need software updates, a service contract is probably the best approach.
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