I85PREP
⌘ K
ENWLSI 300-430 study materials
ENWLSI 300-430 study resources

ENWLSI 300-430: Implementing a Wireless Network

ENWLSI 300-430 · Work through your exam, one topic at a time.

All guide sections

Implementing a Wireless Network

The Implementing a Wireless Network domain tests the base build: controller interfaces, AP discovery and join, mapping WLANs to client VLANs, AP groups and RF profiles on AireOS, and the profile/tag model on Catalyst 9800. Items are usually symptom-driven - you are given a broken binding and must name the object that fixes it.

AireOS building blocks

  • The management interface terminates CAPWAP and carries the AP-manager function on 5520/8540-class controllers; each dynamic interface represents one client VLAN with its own gateway, DHCP and DNS settings.
  • The virtual interface answers web authentication and guest DHCP relay; it must be routable and must never be reused as a client VLAN.
  • Discovery order: local-subnet broadcast → DHCP option 43 → DNS CISCO-CAPWAP-CONTROLLER → previously cached controller → master controller → AP-manager → least-loaded controller.
  • Country code must match the AP's regulatory domain; a mismatch leaves the AP unjoined or its radios administratively down.
  • AP groups decide which WLANs an AP broadcasts; RF profiles group data rates, power and channel settings and are applied to an AP group.

Catalyst 9800 profile/tag model

  • Policy profile = how the client is treated (VLAN/interface, ACL, QoS, session timeout, mDNS service policy).
  • WLAN profile = SSID, security, radio and broadcast policy.
  • Policy tag binds WLAN profiles to policy profiles; site tag sets FlexConnect mode and the AP join profile; RF tag binds the RF profile. Tags are chosen per AP MAC, otherwise the default tag applies.

Worked example

You create SSID CORP on a Catalyst 9800, bind it to policy profile VLAN20, yet clients still receive addresses from VLAN 10. Reasoning: the WLAN profile is bound inside some policy tag, but the AP is still using the default policy tag, which points at VLAN10. Confirm with show ap tag summary and show ap config general <ap>, then apply the correct policy tag to the AP (or edit the default tag). Re-creating the WLAN or rebooting the AP changes nothing.

Traps that cost marks

  • WLAN created and enabled but never added to the AP group, so it is not advertised.
  • FlexConnect local switching with no VLAN mapping - the client associates but never gets DHCP.
  • Editing the 9800 WLAN profile while forgetting the policy profile that carries VLAN and ACL.
  • DHCP option 43 typed in ASCII instead of hex, or a country code that does not match the AP.