QoS aware router

Posted on 2005-04-20
Last Modified: 2013-11-29
Are there routers available in market that can re-route the traffic based on QoS ? For example, if data rate of a Video Stream decreases due to an increase in congestion along the path then the router will re-route the stream dynamically to a different path to ensure the QoS for the video traffic.
Question by:FaysalAdeem
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    Expert Comment

    You're asking the router to know what type of latency/bandwidth the applications requires, that is not the routers job.  What the router will do
    is prioritize traffic in such a way that depending on an application class (lets say VOIP/SIP traffic) the router will ensure that your applications gets priority handling.  This prioritization can be done automatically (this is a very crude method, the router may only use things like the TOS field to prioritize the traffic).  The other traffic shaping is done manually.  There are routing systems that will analyze things like link latency and allow you to re-route traffic.

    Author Comment

    Traffic shaping router will only prioritize the traffic i.e. in case of congestion, it will drop the packets belonging to low priority class but I want to know if there are routers that can dynamically re-route the traffic instead of dropping any traffic ? I do understand that this is not the job of a conventional router since router is network layer device and does not read the application header, but just wondering if there is any such non conventional commercial router available ? One such device which does application level packet shapping is Packeteer ( but it is not a router. Secondly, can't a router estimate the latency/bandwidth on a specific route ? Also I want to know if the TOS field indicate application traffic classes such as SIP and VOIP ?

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    Accepted Solution

    The following link is a pretty good explanation of quality of service.

    I just thought of the only way that I can think of where a router will re-route traffic is based on MPLS traffic policies.  It should be possible to use MPLS to have traffic prefer a certain path.  In order for this to work, you need to have MPLS switched traffic from source to destination (or as close as possible to such a situation).

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