Cisco QoS Guidance

cisconetworkingqos

I have a 10M connection to the internet that is hooked into a 100M port. I am getting started with QoS, and am hopping for a little guidance on setting it up on a Cisco 3825 router. Right now I am going forward with the idea that I have to implement it on my router, and the provider can't provide QoS for me.

How I envision it working is that the QoS will drop or queue packets on my router and that will help prevent a situation where the provider has to start dropping a lot of packets. Right now all I am tasked with is making sure that one of the 3 LANs gets a certain slice (say 3M for Gig Lan1) of the 10M internet connection (But ideally this will be more flexible in the Future).

            10M Internet on 100M port on HWIC-4ESW
                  +-----------------------+
                  |                       |
         Gig Lan1 |      Cisco 3825       | Lan3 on HWIC-4ESW
                  |                       |
                  +-----------------------+
                          Gig Lan2

I need to learn more about QoS, but having a target technology and maybe example configuration will help me wrap my head around the reading I am doing a little more.

  • Which Cisco QoS Technology do you recommend for this particular situation?
  • Have a basic sample config of how this might work?

Right now the 10M line is not congested, so this more to have something in place in case it starts to become mildly congested in the future.

I do have VOIP at one location connected to this one over the Internet that goes through a VPN tunnel. Everything else that is between this location and other offices is on a separate MPLS network.

Best Answer

Whhich bandwidth are you concerned about - outgoing or incoming? If you do not have control over Service Provider's router, you can't achieve true QoS(when you can make sure certain kinds of traffic get more priority than others) for incoming traffic. What you can do though, is to limit certain traffic on your router, ensuring that the remaining portion is available to the target network. For example, you can limit traffic(or certain kinds of traffic, like streaming videos) on LAN2 and LAN3 interfaces which will guarantee that LAN1 always has 3mbits available.

In Cisco terminology this is called traffic policing(as opposed to shaping for true QoS) This document is a good start : http://www.ict-partner.net/en/US/docs/ios/12_2/qos/configuration/guide/qcfpolsh.html#wpxref40342

Related Topic