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Cisco · ISE 3.3 · Lesson 3 of 12

NAD + RADIUS: the switch must speak ISE’s language

ISE policy is perfect. The switch still has a 20-year radius-server host and no CoA. ISE cannot bounce the port or push a dACL. This lesson is the NAD object and the IOS side.

Updated 2026-08-18·20 min read·L2 primary·Quiz at end

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The ticket

Live Logs: “Unknown NAD” or silent drop. Or Access-Accept but no dACL. The switch secret is Cisco123. ISE NAD object has LabSecret.

Quick interview answer

A NAD is the switch/WLC ISE trusts. Path: Administration → Network Devices. The device IP, device type, and RADIUS shared secret must match IOS. CoA (Change of Authorization) needs the switch to allow ISE to re-auth the session. dACLs need ip device tracking / IPDT and RADIUS authorization.

Hero · switch to PSN
Access switch sending RADIUS to ISE PSN
Wrong secret = ISE never sees a valid request. Policy never runs.
Lab data · dummy only

PAN ise-pan 10.10.10.20 · PSN ise-psn1 10.10.10.21 · MnT ise-mnt 10.10.10.22 · NAD sw-access-01 10.10.10.2 · AD dc01 10.20.30.10 · Priya 10.20.30.80 TECHCLICK\priya.hr · printer 10.20.30.60. Not a live customer.

What a NAD is

ISE only answers NADs it knows (or a default device if you were sloppy). Location/device-type attributes later drive policy-set conditions.

https://ise-pan.techclick-lab.in/admin
Training mock · not live
Context VisibilityOperationsPolicyAdministration
Administration → Network Devices

sw-access-01

sw-access-01
10.10.10.2
Cisco Catalyst
•••••••• (lab only)
Enabled
ISE Admin Guide — Network Devices. Training mock.

What the switch must send

NeedIOS idea
RADIUS to PSNradius server ISE-PSN1 address 10.10.10.21 auth-port 1812 acct-port 1813
AAAaaa new-model + authentication/authorization/accounting dot1x
CoAClient source ISE PSN, server key match
dACLRADIUS authorization + device tracking

Both sides

  1. Side A — ISE NAD

    Network Devices → Add. IP 10.10.10.2. Same secret. Enable RADIUS and CoA.

  2. Side B — switch

    Modern radius server syntax. Point only at PSN .21 (and a second PSN later). Do not point at PAN.

  3. Side C — prove

    test aaa. Live Logs show the NAD name sw-access-01, not Unknown.

IOS · dummy lab
aaa new-model
radius server ISE-PSN1
 address ipv4 10.10.10.21 auth-port 1812 acct-port 1813
 key LabSecret
aaa group server radius ISE-GRP
 server name ISE-PSN1
aaa authentication dot1x default group ISE-GRP
aaa authorization network default group ISE-GRP
aaa accounting dot1x default start-stop group ISE-GRP
aaa server radius dynamic-author
 client 10.10.10.21 server-key LabSecret
ip device tracking
test aaa group ISE-GRP TECHCLICK\priya.hr LabPass new-code

Four NAD failures

1 · Shared secret mismatch

No useful Live Log, or dropped request. Re-type both sides. Do not debug policy.

2 · NAD IP is the management VRF ISE never sees

Source IP of RADIUS ≠ NAD object IP.

3 · No CoA

Profiling/posture changes never bounce the port. Session stays stale.

4 · RADIUS pointed at PAN

PAN may not be a PSN. Timeouts.

How to prove it

Close the ticket only when

1) test aaa returns a clear Accept or Reject (not timeout). 2) Live Logs NAD = sw-access-01. 3) CoA client listed. 4) Secret never written in a ticket body.

Traps

SymptomNAD storyWrong fix
TimeoutIP/secret/personaNew authorization rule
Unknown NADObject missing / wrong IPOpen any NAD
Accept, no dACLauthorization / IPDTDisable 802.1X

Knowledge check

Judgment items. One best answer. Reasons send you back to the matching section.

Q1

Where is the NAD created?

Correct: b. Admin path.
Q2

Switch should send RADIUS to…

Correct: b. Lesson 1 + this runbook.
Q3

Shared secret mismatch first looks like…

Correct: a. Failure 1.
Q4

CoA is needed so ISE can…

Correct: a. Concept.
Q5

test aaa is run on…

Correct: a. PDF: simulate from switch CLI.
Q6

Unknown NAD in Live Logs means…

Correct: a. Failure 2.

Cisco ISE class series: Personas · First day · NAD + RADIUS · Policy sets · Wired 802.1X · MAB · CWA / guest · Profiling · dACL vs VLAN · Live logs · vs Forescout · Interview

Sources

Related: ISE evidence desk · session factory · Forescout series.