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New Member

interview question

what is the diffrence between QOS & policy based routing

experts pls help


Re: interview question

Hello Sunil,

Quality of Service governs how traffic is handled. It classifies, marks, queues, polices and/pr shapes traffic according to a pre-defined service level.

Policy-Based Routing is used to manipulate how traffic is forwarded based on source/destination address, routing information and/or tags.

You can read more on these subjects here:

Please rate posts.


Re: interview question


QOS: consider you are having large network and having most of all type of data traffic. Now think about the voice data and bulk ftp data... when your multiple user have file transfer application and which make your network congested and at the same time your voice data is also travelling through that time due to bulk file transfer data your voice traffic has to suffer from delay and some time due to congestion packet loss also will take that time you have to upgread your bandwidth as well as infrastructure (interms of high processing router and switches) in order to get best performance and other think is you can use some softwarebas or you can say the logical tools like qos at that time... so in congestion situation you can tell your network device to give high priority to your voice data...then again one point come into mind how to identify that time CLASSIFICATION come in to you have to put the mark on that high priority at that time MARKING come in to role...smilarly you have mark voice data as high priority and ftp as low then again you have to put voice data seperate and ftp data seperate ...or you have to put your voice data first and then ftp data... or you can say voice data will be placed at high priority location and ftp as some what lower...then QUEUING come in to the role... and along with that SHAPING AND POLICING is also this is how with out upgreading your physical infrastructure you can able to get better performance in your network using QOS...

now talk about policy base you can manuplate your data packet and can assign appropriate outlate for it...or you can have more power using routmaps and you may make router to work according to your requirement...

hope this will help you to understand

rate this post if it helps



New Member

Re: interview question

QoS is creating priority for certain traffic via the same path and route. It is like a taxi/bus lane or a emergency vehile with sirene. They usually follow the same route/path

Example : Voice

Policy based routing is choosing a different path/route for certain traffic with the same desination. It is like sending lorries with dangerous loads trhough a differen path to avoid the tunnel.

Example: HTTP via a proxy, FTP via an different proxy.