Download Implementing Cisco Enterprise Network Core Technologies (350-401 ENCOR).350-401.PassLeader.2021-04-22.353q.vcex

Yet Another Next Generation (YANG) is a language which is only used to describe data models (structure). It is not XML or JSON.

Mobility Express is the ability to use an access point (AP) as a controller instead of a real WLAN controller. But this solution is only suitable for small to midsize, or multi-site branch locations where you might not want to invest in a dedicated WLC. A Mobility Express WLC can support up to 100 APs. Mobility Express WLC also uses CAPWAP to communicate to other APs.  Note: Local mode is the most common mode that an AP operates in. This is also the default mode. In local mode, the LAP maintains a CAPWAP (or LWAPP) tunnel to its associated controller.

Agentless tool means that no software or agent needs to be installed on the client machines that are to be managed. Ansible is such an agentless tool. In contrast to agentless tool, agent-based tool requires software or agent to be installed on the client. Therefore the master and slave nodes can communicate directly without the need of high-level language interpreter.  

The tunneling technology used for the fabric data plane is based on Virtual Extensible LAN (VXLAN). VXLAN encapsulation is UDP based, meaning that it can be forwarded by any IP-based network (legacy or third party) and creates the overlay network for the SD-Access fabric.  Although LISP is the control plane for the SD-Access fabric, it does not use LISP data encapsulation for the data plane; instead, it uses VXLAN encapsulation because it is capable of encapsulating the original Ethernet header to perform MAC-in-IP encapsulation, while LISP does not. Using VXLAN allows the SD-Access fabric to support Layer 2 and Layer 3 virtual topologies (overlays) and the ability to operate over any IP-based network with built-in network segmentation (VRF instance/VN) and built-in group-based policy.

The TCP port 6514 has been allocated as the default port for syslog over Transport Layer Security (TLS).  Reference: https://tools.ietf.org/html/rfc5425

There are five basic device roles in the fabric overlay: Control plane node: This node contains the settings, protocols, and mapping tables to provide the endpoint-to-location (EID-to-RLOC) mapping system for the fabric overlay.  Fabric border node: This fabric device (for example, core layer device) connects external Layer 3 networks to the SDA fabric.  Fabric edge node: This fabric device (for example, access or distribution layer device) connects wired endpoints to the SDA fabric.  Fabric WLAN controller (WLC): This fabric device connects APs and wireless endpoints to the SDA fabric.  Intermediate nodes: These are intermediate routers or extended switches that do not provide any sort of SD-Access fabric role other than underlay services.

A Cisco lightweight wireless AP needs to be paired with a WLC to function.    An AP must be very diligent to discover any controllers that it can join—all without any preconfiguration on your part. To accomplish this feat, several methods of discovery are used.  The goal of discovery is just to build a list of live candidate controllers that are available, using the following methods: Prior knowledge of WLCs  DHCP and DNS information to suggest some controllers (DHCP Option 43)  Broadcast on the local subnet to solicit controllers    Reference: CCNP and CCIE Enterprise Core ENCOR 350-401 Official Cert Guide   If you do not tell the LAP where the controller is via DHCP option 43, DNS resolution of “Cisco-capwap-controller.local_domain”, or statically configure it, the LAP does not know where in the network to find the management interface of the controller.  In addition to these methods, the LAP does automatically look on the local subnet for controllers with a 255.255.255.255 local broadcast.    Reference: https://www.cisco.com/c/en/us/support/docs/wireless/5500-series-wireless-controllers/119286-lap-notjoin-wlc-tshoot.html

A virtual machine (VM) is a software emulation of a physical server with an operating system.  From an application’s point of view, the VM provides the look  and feel of a real physical server, including all its components, such as CPU, memory, and network interface cards (NICs).  The virtualization software that creates VMs and performs the hardware abstraction that allows multiple VMs to run concurrently is known as a hypervisor.  There are two types of hypervisors: type 1 and type 2 hypervisor. In type 1 hypervisor (or native hypervisor), the hypervisor is installed directly on the physical server. Then instances of an operating system (OS) are installed on the hypervisor. Type 1 hypervisor has direct access to the hardware resources. Therefore they are more efficient than hosted architectures. Some examples of type 1 hypervisor are VMware vSphere/ESXi, Oracle VM Server, KVM and Microsoft Hyper-V.  In contrast to type 1 hypervisor, a type 2 hypervisor (or hosted hypervisor) runs on top of an operating system and not the physical hardware directly. A big advantage of Type 2 hypervisors is that management console software is not required.

Proxy ingress tunnel router (PITR): A PITR is an infrastructure LISP network entity that receives packets from non-LISP sites and encapsulates the packets to LISP sites or natively forwards them to non-LISP sites.  Reference: https://www.ciscopress.com/articles/article.asp?p=2992605