a rainbow of fruit flavors for the network

Do you really use network quality of service within the glass house data center?  This is a question I have been pondering pretty much all day- I get that on the costly WAN links we almost all use it.  I also completely acknowledge that most engineers plan to use some of the QoS features within the data center, but what do we really use?  Which features are necessary and which are just... well...  extraneous?

Here's my thought-   I think there are some  QoS 'hit songs' implemented in the data center, and some that just are not that appropriate for this iMix.

Bad Boy Bad Boy, whatcha gonna queue....
No matter how many security products we surround ourselves with we all have the 'time out queue' for traffic that just isn't, well, good.  It's for those pesky control plane DoS attacks, the misbehaving broadcast storm NIC, or that one application that just won't shut up.

Voices Carry
For some reason I have the 80's Til Tuesday song in my head by the same name- but most engineers I have talked with seem to set up, by default, a strict priority queue for voice traffic, then never,ever touch it again because it just works.

Marky Mark and the Funky Bunch
We all use markers, especially at the edge where we can have maximum visibility to what comes from a single host, and mark it up appropriately so that we don't have to continuously re-inspect and re-apply policy everywhere.  Tag at the edge, queue in the core, shape on the WAN or point of massive congestion/cost.

(Don't) Drop it like it's Hot
No matter what religious SCSI encapsulation you love- FibreChannel, FibreChannel over Ethernet, iSCSI or even file based alternatives such as NFS or CIFS storage just performs better when is is not dropped.  As much as I love technologies like Aspera for moving large files from A-to-B, until it is integrated in my host stack (which would monumentally rock for copying my iTunes library to S3 btw, hint...) the world will be dependent on TCP-guaranteed or PFC/BCN guaranteed storage delivery for a while - so we need a "lossless don't-drop-me-please" queue.

Shape ya Tailfeather
As we hit congestion and contention for bandwidth in a well designed data center this happens at the cost-center link, i.e. the edge router: this is where I apply large buffers, shapers, and policers to ensure that traffic can en-queue long enough to get onto the link, we can also adhere to Peter Lothberg's long-time rule of providing enough buffer to handle a round-trip-response of around the world or ~300ms.  Shaping the previously marked-up traffic onto the link while trying to get all the right traffic on the link is the job of the core routers, usually not fixed switches.

That's it for now, any songs I should also think about including into the Data Center QoS Playlist?

dg