PBR Based on Utilization

Routing & Switching
1

I have generic question
Let say I have ISP1 and ISP2, both same bandwidth
I want to route my video conference to the best link but choose anything else like torrent to cheaper rates

QUESTIONS:

  1. can I use PBR for that
  2. how to measure best video link.
    should I check by speedtest
    is better speed equal to lower latency
    tq
2

Hello Nawir

The first thing you need to do is differentiate between specific types of traffic. You must identify your video conference traffic, and differentiate it from the rest. This can be done using classification and marking, two things that you can learn more about in these lessons:



Video packets can thus be marked with the appropriate DSCP values based on your QoS scheme.

Next, you can indeed use PBR to give preferential treatment to those marked packets. Based on the DSCP values, you can choose to route them differently. The following lesson describes PBR.


Instead of matching a particular IP address such as in the lesson, you can match a particular DSCP value and choose how to route it.

Now to the hard part of your question. How do you measure the “best link” in order to route traffic there? It depends on what you want to measure. The utilization at that specific point in time? The ping response time? A speed test? Well, the first two you can probably do using an EEM script where you can periodically test these parameters and use their results in a PBR. However, you cannot always guarantee that the link is better simply based on usage or latency.

Even so, having the router determine, for each individual packet, which link is preferrable at that point in time can get very CPU intensive, and unnecessarily complicated. It could also cause problems in the video stream, especially if packets are constantly being routed via different routes, causing an extensive number of out of order UDP packets.

Rather than dynamically choosing the best link at that time, it is preferable to make one of the links preferable in other ways and always use that link. For example, depending on your requirements and the expected traffic patterns:

  1. Make that link exclusively for video traffic usage, so it is clean from any other traffic that may cause congestion.
  2. Apply some form of queuing on the link so that priority packets are served without delay.
  3. Ensure that the physical bandwidth of the link is sufficient for your requirements

This way, routing can be more stable and efficient, and your video services can enjoy better service from the one preferred link.

I hope this has been helpful!

Laz

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