I’m in the process of deploying a pair of Nexus 93180YC-EX switches for our new campus, and have learned that the APIC-EM EasyQoS module does not support the 9k platform. For those unfamiliar:
“The EasyQoS solution abstracts QoS policy by using a declarative model as opposed to an imperative model. A declarative model focuses on the intent or WHAT is to be accomplished, without describing HOW it is to be accomplished.” (http://www.cisco.com/c/en/us/td/docs/solutions/CVD/Dec2016/APIC-EM-EasyQoS-DesignGuide-Dec2016.html#_Toc469388744)
I’ve been playing with APIC-EM and like that it simplifies QoS design for the campus, especially because I can visually involve management in the QoS strategy. Without support for the 9k, we’re back to using the MQC and classifying traffic with ACLs. Not a big deal, until you realize that creating a comprehensive QoS policy on the 9k can quickly exhaust the TCAM with the default allocations.
A brief overview of this deployment:
Enterprise Services licenses were not purchased so the 9K switches will be operating in L2 mode. Layer 3 will be handled in the campus core, a pair of Catalyst 6880s running VSS. 2248TP-E FEXs will be hanging off the 9Ks in a straight-through configuration, with dual-homed servers connected via vPC. QoS marking, classification, and queuing will be configured based on the company’s defined business-important traffic and attached to host interfaces on the 9k or FEX.
Because of the potentially high number of Access Control Entries (ACEs) in the ACLs used for traffic classification, it’s important to understand how TCAM space will be consumed in order to prevent interfaces from being err-disabled due to TCAM exhaustion. This understanding is fundamentally the same as with the Catalyst switches, so this series of posts is being written with the following objectives:
- Where possible, identify the differences between the 93180YC-EX (and, presumably, other second-generation 9300 series Nexus switches) and the original product line. These observations are based on my experience configuring the 93180 versus the documentation available from Cisco.
- Demonstrate methods for determining TCAM utilization and estimating TCAM space requirements for QoS.
- Identify opportunities to optimize TCAM utilization in order to reduce the potential for resource exhaustion.