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Link 100% utilised


I am asking this general question:

what are the causes of having link utilization of 100% and how can we troubleshoot that?

what can i work on if i have that link connecting two site? I have other backup link but I want to use that secondary link when primary goes down?


Devang Patel

Super Bronze

Re: Link 100% utilised

Why do you believe 100% utilization needs troubleshooting? The common cause is one or more tranmission sources with at least as much bandwidth as the 100% usage link and those source or sources want to move data at their maximum speed.

With regard to using the secondary link when the primary fails, is the secondary link always up or only up by on-demand? If the former, routing metrics can move traffic to a secondary path when the primary path is unavailable. For the latter, link activation is triggered by lost of the primary link. How that's accomplished depends on the nature of the primary and secondary links.

Re: Link 100% utilised

Hi Devang,

100% of a link utilization means you are consuming the whole bandwidth of link, If you believe you dont have applications that consumes your whole PIPe, then you probably have viruses, malwares running that could impact the Network performance & consumes extra bandwidth.

If you believe its normal traffic , and you have sensitive applications needs special treatment, then you should apply QoS (congestion Managment) to priotrize traffic over another when congestion occurs.




Re: Link 100% utilised

If link is experiencing 100% utilization, I would check the output queue on the interface to see if any traffic is being discarded. If so then need look deeper into the traffic consuming bandwidth.

You could enable Netflow between the site to determine what the traffic is and top connections. You can download Scrutinizer for free with limited netflow resources.

or you can place a sniffer ( Free Wireshark) on segment by spanning the uplink to the router from local switch.

Depending on your routing protocol you can load balance across the two links to ease utilization, or depending on topology load balance using HSRP or GLBP. I would recommend load balancing across the additional link. each link will back up the other should one go down. also, if you are paying ofr a backup link, why not use it.

Check URL - CEF / OSPF load balance

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