License and Registration, Please.
You won't get anywhere without a license. In past implementations of routing and switching operating systems such as Cisco's classic, industry standard, IOS, we were able to use a switch without a license. It was something many people overlooked when complaining about Cisco Smartnet pricing, but was and is a convenient luxury that Cisco Business switches provide. However, as we introduce Cisco's Data Center switches like the Cisco Nexus series 9K, 7K, 4K, etc., we have a new OS… Each switch has a unique Host ID and can generate a .lic file. You can use licensing to pay for things a la carte, reducing the overall cost of ownership. Some features requiring a license are port channels, Layer 3 SVI, HSRP, VRRP, different routing protocols, and more.
NX-OS, the Next OS Nexus
NX-OS is the Operating System for the Nexus series data center switch lines. It's similar to the CatOS or IOS-XE variants in that different commands don't work on regular IOS. So, if you tried jumping onto the command line it has a lot of key configuration differences between other OSes. It may be utterly overwhelming, without the proper primer. There are many things you used to do that will get you ruined on NX-OS. Example:
The write memory command used to be a way to save your configuration on IOS. It is not uncommon for Cisco to do this; if you're a bit older you might remember a time when the Cisco Catalyst series switch line ran CatOS, a version of IOS that was layer 2 only, and routers ran IOS. The rise of the layer 3 switch changed everything and CatOS features were merged into IOS. Today, Cisco Service Provider gear such as the ASR (Advanced Services Router) 1000 runs the IOS-XE variant of IOS. These are just a few of many such examples.
You can no longer use write memory to save. You will have to use another option, such as copy running-config startup-config, which copies the current running configuration to the startup configuration location.
Features
Everything in IOS would be enabled by default based on the version of the OS you ran, for example, IP-Base vs IP-Services. However, now you will need to implement each technology feature with a command of syntax “feature-set [feature]”.
Here is Cisco's feature tree for ACI + NX-OS + Day 2 Ops, and how you can order each feature a la carte. It is important to note that we will be dealing with the N9K and the specific differences in licensing between the 9000 and 3000 (N9K vs N3K pictured).
Style and Grace: Cisco's Grace Period Allows 120 Days of Feature Usage for Free
For approximately 120 days, you can enable any features you wish and experiment with whether you want to keep them or not using the license grace-period command. Cisco believes strongly in their products and would prefer you to use the advanced features even if just to see if you like them or not without committing money to buying them. This is because they have recorded data that customers who do try the grace period feature out tend to want to buy more features on the final purchase order. This doesn't come without restrictions: you cannot have more than one VDC during the grace period, so get the licensing as soon as possible.
Inter-Switch Link: End of Support, Dot1Q on N9K
Inter-Switch Link: End of Support, Dot1Q on N9K with application-specific infrastructure switches like the Cisco Nexus series. We can assume every trunk port when we need a trunk port, is going to be dot1q by default, as ISL trunking is not supported. But didn't Cisco make ISL? Sure, and they have continued supporting it for many years even after the industry had decided it was in general inferior to dot1Q. The following reasons detail why dot1q is enabled now and not ISL: A) Cisco wanted to rush the best solution to market back when it developed ISL as a solution for running multiple VLANs on a connection between switches. They provided, at the time, the best possible solution, with the best features, in the quickest time possible, regardless of whether standards have been developed which took time to ratify. B) the potential risk of another vendor's switches entering your network is never zero percent, even for most Cisco-only buyers. C) Dot1Q only adds 4 bytes of overhead versus 26, with ISL, and that adds up. Also, dot1q supports 4,096 VLANs. So a customer back decades ago may have needed VLAN tagging to utilize daisy chaining the gear off one PoE port that powers the phone and has a port to connect the workstation internet to… and they would not have been able to do this without VLAN tagging. Therefore, they would have had to purchase twice the amount of ports. The wise engineers at Cisco stepped in with ISL and saved the day, but they had to whip up ISL in a hurry, and while it was fully baked, it wasn't as well thought out as a solution as dot1Q would be, with not quite the scalability. Cisco is constantly adapting to meet the demands of the public and private sector and sometimes there is a greater need to have access to the bleeding or leading edge features. While it seems silly to call ISL high-tech, if you go back twenty-five years, it was a new feature.
