I probably should have made notes on the Cisco Nexus platform and its features when I first started playing with them back in 2010/2011, it would have saved me running over it again and making new notes. Although quite a few new features have been introduced since then 
Key Features of the NXOS;
- VDC (Virtual Device Contexts)
- vPC (Virtual Port Channel)
- Continuous System Operation (ISSU etc.)
- Security (802.11AE, CTS, ACL, port security etc.)
- L2 protocols/services (STP, VLAN, PVLAN, UDLD etc.)
- L3 protocols/services (OSPF, BGP, EIGRP, PBR, PIM, GRE etc.)
- OTV (Overlay Transport Virtulisation)
- MPLS
- Fabric Path (pre TRILL standard and Cisco proprietary)
Platforms that run NXOS;
- Nexus 7000
- Nexus 6000
- Nexus 5000
- Nexus 4000
- Nexus 3000
- Nexus 2000
- Nexus 1000v
- MDS 9000
- UCS (Unified Computing System)
NXOS has different types of management interfaces;
- Controller Process (CP)/Supervisor – Both the management plane and control plane and is critical to the operation of the network.
- CMP (Connectivity management Processor) – Used for out of band management and monitoring. It is independent from the primary OS. Enables lights out management of the supervisor and all modules.
- Mgmt0 – Out of band management through a dedicated interface and VRF, ensures isolation from the control and data planes. When configuring vPC a best practice is to NOT use this interface for the vPC keepalive link
- eXtended Markup Language (XML) – management, monitoring and communication via NETCONF.
- SNMP – Used as with traditional devices
The following Embedded Serviceability features exist;
- SPAN
- ERSPAN
- Embedded Analyser (only captures control plane traffic)
- Smart Call Home
- Configuration Checkpoints & Rollback
- Neflow
The network management tool the Cisco offer to manage these boxes is called Data Center Network Manager (DCNM). Surprise surprise it is yet another tool based on Java! It uses the XML interface to manage and monitor them. A nice feature is the configuartion rollback which allows you to take a snapshot or checkpoint of the configuration and then reapply it withut the need to reload the device.
Operating System Files
The NXOS software is a little different to IOS and contains 3 images, this is similar to what SAN-OS used (which is no surprise as that was the platform NXOS was built on);
- Kickstart image – Linux kernel, basic drivers and initial FS
- System image – system software
- Erasable Programmable Logic Device (EPLD) – found on the I/O modules (not updated that often)
NXOS supports in-service software upgrades (ISSU), these upgrades are performed without disrupting data traffic. Upgrades to the EPLD does cause disruption.