Exam Notes For CCNP ENCOR Certification

III. Infrastructure

1. Describe network virtualization concepts

1.3 Wireless

Describe Layer 1 concepts, such as RF power, RSSI, SNR, interference noise,band and channels, and wireless client devices capabilities

SNR (Signal-to-Noise Ratio) is a ratio based value that evaluates your signal based on the noise being seen.SNR is comprised of 2 values and is measured as a positive value between 0db and 120db and the closer it is to 120db the better: signal value and noise value typically these are expressed in decibels (db).

RSSI (Received signal strength indication) will look at the Signal (Also known as RSSI) first this value is measured in decibels from 0 (zero) to -120 (minus 120) now when looking at this value the closer to 0 (zero) the stronger the signal is which means it's better, typically voice networks require a -65db or better signal level while a data network needs -80db or better.

Describe AP modes and antenna types

LAP (Lightweight AP Protocol [LWAPP]): A Cisco LAP is part of the Cisco Unified Wireless Network architecture. An LAP is an AP designed to be connected to a wireless LAN controller (WLC). The WLC manages the AP configurations and firmware; therefore, the LAP cannot act independently of a WLC. This mode is sometimes called controller-based. Enterprise Networking and Security content require lightweight mode.

Autonomous AP: A Cisco IOS Software-based AP that functions independently of a WLC. This mode is sometimes called standalone. Collaboration and Customer Collaboration content require autonomous mode.

CAPWAP (Control and Provisioning of Wireless Access Points): CAPWAP encapsulates the data between LAP and WLC within new IP packets. The tunneled data is then switched or routed over a campus network.

1.4 IP Services

Describe Network Time Protocol (NTP)

This is an example of output from the "show ntp status" command:

SW01#show ntp status
Clock is synchronized, stratum 2, reference is 10.4.2.254
nominal freq is 250.0000 Hz, actual freq is 250.5320 Hz, precision is 2**18
reference time is D36968F7.7E3019A9 (02:12:07.492 UTC Fri Mar 05 2020)
<output omitted>

From the above output, we know that the IP address of the reference is 10.4.2.254 and that the Switch SW01 has synchronized with the reference.

IV. Network Assurance

1. Diagnose network problems using tools such as debugs, conditional debugs, trace route,ping, SNMP, and syslog.

This is a syslog config command, where you want to collect the logs related to the trap level you configured via this command.

Trap level is nothing but the severity level, and lower the trap level/number higher the severity.

SNMP trap logging:The router can send syslog message to an external SNMP server. This is accomplished using SNMP trap.