QoS in our Datacenter

Quality of Service (QoS) is a very important feature for a Datacenter, as they have a huge amount of traffic. In a DC we can find some services more critical than others and therefore those should have a higher priority.

We previously tended to separate networks for different traffic, but not anymore and now we try to make an integration of services on the same network. This helps in managing and maintaining the network, but traffic increases considerably as do the problems.

Thanks to the different QoS policies we can choose what traffic and what priorities should be applied all times.

Some of the most basic attributes to be controlled by these QoS are.

• Bandwidth
• Delay End to End
• Jitter
• Lost Packets

As we said, we will implement QoS in our DC using the devices from Juniper MX Series (same devices that we use as router). These devices allow two types of implementation, MPC and DPC.

• MPC (Modular Port Concentrator): Includes 5 types and provide shipping packages services. They use mics (Modular Interface Cards).

They allow great modularity characteristics since the cards can be configured and controlled separately from the configuration of the ports. These modules enable QoS level 2 and 3.

• DPC (Dense Port Concentrator): There are three different types and they provide physical interfaces and PFE (Packet Forwarding Engines).
  • DPCE-X: Its main feature is the optimization of the layer 2 (Ethernet).
  • DPCE-R: Does the same as above, but offers a higher routing and processing speed.
  • DPCE-Q: Its main function is to increase efficiency in the management of queues and QoS techniques such as WRED, RED, WRR, etc.

In our DC we need QoS level 2 (QFabric) and level 3 (routers). Regarding the level 2, it will apply to access switches, since the distribution and core require higher processing speed.

For QoS level 3 we will be using DPCE-Q, because the other two are more focused on level 2 policies. And here we require more efficient queuing techniques such as those mentioned above, WRED, RED, etc.