QoS in data centers

If you have been wondering how to prioritize traffic, this is the post you’ve been waiting for. To give preferences over different traffics the network might have, it’s important to use Quality of Service, or most known by QoS.

We also have some requirements to fulfil related to QoS. These requirements are:

• DNS equipment and port management of all devices.
• Centralized management of each manufacturer.
• Prioritize critical transitions over the Internet.

We don’t have to forget that we have to compare our solution with Cisco’s solutions, so by the end of the post we’ll be doing a little comparison.

Checking all the LAN devices we’ve selected to do our data center’s network, we can see that all of them support the 802.1q standard.

So to distinguish the different traffic, we’ll be using VLANs, by now we’ve chosen the Management, Applications, Storage and Backup VLAN. According to which VLAN the traffic belongs, the servers and switches will mark all packets with the corresponding VLAN so this way it’ll be easier to prioritize traffic. The external traffic will be marked by the router.

We’ll also have different queues according the priority of the VLAN, so the Storage VLAN, which is the one that will need most bandwidth, will be the one with the maximum priority, the rest of them will be marked according to the bandwidth they want to use.

So the traffic will be classified in 3 different categories:

• Best effort (BE)
• Assured Forwarding (AF)
• Expedited Forwarding (EF)

Being the EF the most prioritized queue and the BE the one with less preference.

A bad configuration can lead to important delays and bad user experience due to congestions.

We have to take in mind that QoS is a software that runs over a hardware so different manufacturers can offer similar solutions but with the same idea. So at this point, offering an example of Cisco’s solution would be similar to our brocades solution.

Hope you’re still interested in data centers! See you next week!!