Test your basic knowledge |

CCNP Wireless Security

Instructions:

Answer 50 questions in 15 minutes.
If you are not ready to take this test, you can study here.
Match each statement with the correct term.
Don't refresh. All questions and answers are randomly picked and ordered every time you load a test.

This is a study tool. The 3 wrong answers for each question are randomly chosen from answers to other questions. So, you might find at times the answers obvious, but you will see it re-enforces your understanding as you take the test each time.

1. 2 different types of wIPS deployment
ACL - or Interface-name configured in ACS -1. Interface Configuration --> RADIUS (Cisco Airspace) and check off: Air-Qos-Level - Aire-DSCP - Aire-802.1p tag - Aire-Interface-name - Air-ACL-Name
Inter Access Point Protocol uses UDP between aps to exchange information about new aps (announce) in the area and handoffs that have occurred when client roams
1. Integrated -- wIPS monitor mode aps are part of client-serving infrastructure 2. Overlay -- wIPS aps - WCS & WLCs are totally seperate
1. Captive Portal 2. NAA (agent installed on windows); auth twice (1 to radius 2 to nac) 3. NAA w/ SSO - user authss once. & wlc auths to nac on their behalf.

2. Authentication types used by SNMPv3
1. HMAC-MD5 2. HMAC-SHA
1. CAPWAP 2. NMSP (network mobility services) 3. SNMP 4. SOAP/XML
Sends the PMK to all WLCs that the client can roam to.
uses TLS to secure other eap methods like certs - user/pass - smart cards. Identifies itself to client with certificate. Utilizes: fast reconnect (faster roaming w/ key caching) and server authentication

3. Steps to auth with NAA w/ SSO
1. User performs .1x with RADIUS 2. WLC forwards radius accounting start to NAM (along with clients IP) 3. clients NAA detects network con. & tries to connect to NAM. 4. NAS Intercepts step 3 & contacts NAM itself to see if client is in the online li
EAP-FAST with anonymous pac provisioning
MFP
1. Captive Portal 2. NAA (agent installed on windows); auth twice (1 to radius 2 to nac) 3. NAA w/ SSO - user authss once. & wlc auths to nac on their behalf.

4. How to set up tacacs roles in ACS for WLC authorization
uses TLS to secure other eap methods like certs - user/pass - smart cards. Identifies itself to client with certificate. Utilizes: fast reconnect (faster roaming w/ key caching) and server authentication
Check Shell(exec) then define roles as role1=MANAGEMENT role2=WLAN role3...etc
-150ms
mping = tests intercontroller control traffic. eping = tests intercontroller data traffic (EoIP)

5. How long before an HREAP goes into disconnected/standalone mode
1. In-band virtual gateway -- is at L2 and intercepts all traffic and re-tags the default/untrusted vlan to the trusted vlan - based on compliance 2. In-Band Real IP Gateway - is the gateway 3. Out-of-band virtual gateway (same is 1 - except traffic
300ms
100 local accounts max
1. on NAS create an oob profile for the WLC 2. Create a new device in NAM - specifying the WLC mgmt ip 3. device mgmnt-->NAS & add the NAS ip as an oob virt. gateway 4. still on nams nas config page - enter the nas trusted int. ip & untrusted int vla

6. NAC Deployment Types
1. Temporal Key for Unicast 2. Key Confirmation Key (KCK) - used for group handshakes 3. Key Encryption Key (KEK) - for encrypting the group encyrption key used to derive the braodcast/multicast keys.
1. In-band virtual gateway -- is at L2 and intercepts all traffic and re-tags the default/untrusted vlan to the trusted vlan - based on compliance 2. In-Band Real IP Gateway - is the gateway 3. Out-of-band virtual gateway (same is 1 - except traffic
puts the ap and client through tests to isolate connection issues. This disables the wlan while doing this. Can be used to diagnose .1x auth - .11 association etc. if using ccxv5
1. Integrated -- wIPS monitor mode aps are part of client-serving infrastructure 2. Overlay -- wIPS aps - WCS & WLCs are totally seperate

7. What triggers can initiate a WLC to request a client to roam
same as steps to roaming in non-802.1R except: skips PMK negotiation & piggybacks PTK & QoS with the 802.11 authentication & association messages
1. Guest User 2. Sponsor 3. Network Enforcement Device (ie wlc) 4. NGS Server itself
WLCs create a deriviative of the PMK - called Opportunistic Key Caching (OPC) for fast-roaming among HREAPs in the same HREAP group.
1. Min. RSSI 2. Roam Hysterisis - how much higher than current RSSI compared to neighbor ap RSSI before roaming request initiates 3. Scan Threshold - How low the current RSSI must be for the client to start scanning for a better ap 4. Transition Time

8. Steps to configure wlcs for guest wlan
1. config mobility list to support anchor & foreign wlcs (using different mob. groups on ea. to keep auth. seperate between anchor & foreigns) 2. Map the guest wlan on foreign wlc to either mgmt int. or fake dynamic int. (ie dynamic int tied to a vla
checking allow aaa over-ride in the wlan-->advanced.
1. application type 2. security capabilities 3. QoS policy
Clients send info re: previously associated aps to current ap - so it can use this information to inform current clients about neighboring aps. Requires CCXv2

9. How is IBN-VLAN Selection implemted in ACS
1. disassociation 2. deauthentication 3.QoS (WMM)
1. Interfac Configuration --> RADIUS (IETF) --> check 64 (Tunnel Type) - 65 (Tunnel Medium Type) - 81 (Tunnel Private-group-id) 2. Navigate to Group Setup and enable the checkboxes for the previous attributes - where 64=VLAN - 65=802 - 81=<Vlan_tag>
1. CBC-DES 2. CFB-AES-128
EAP-FAST with anonymous pac provisioning

10. What ports does OEAP use to connect to anchor WLC
assigning multiple vlans to single wlan - and users are dynamically mapped to one of the vlans in round-robin
1. Wireless-->AP Global Config-->enable dot1x w/ user/pass 2. Config the switch port to enable auth. to ACS/RADIUS
UDP 5246 & 5247
is provided to clients as they associate - including neighbor ap info like channel - rssi etc.

11. What is included in a Pairwise Transient Key (PTK)
1. Temporal Key for Unicast 2. Key Confirmation Key (KCK) - used for group handshakes 3. Key Encryption Key (KEK) - for encrypting the group encyrption key used to derive the braodcast/multicast keys.
checking allow aaa over-ride in the wlan-->advanced.
1. Create user acct. in IDS for each WLC in the viewer role 2. add the WLCs IP as an allowed host 3. Obtain the IPS TLS Fingerprint & add it to WLC 4. Enable the client exclusion policy on the WLAN 5. Set msg log level to Alerts to log IPS events
a mobility list can contain multiple mobility groups

12. Client Roaming Reasons
MFP
1. In-band virtual gateway -- is at L2 and intercepts all traffic and re-tags the default/untrusted vlan to the trusted vlan - based on compliance 2. In-Band Real IP Gateway - is the gateway 3. Out-of-band virtual gateway (same is 1 - except traffic
mititgate non-802.11 attacks
1. RSSI 2. SNR 3. Load-Ballancing

13. Steps to installing Server Cert into ACS
what occurs as a client roams to new ap -WLC forwards cached PMK to AP. Client then forms a Pairwise Transient Key (PTK) via 4-way handshake w/ ap.
1. Log into cert. server - from ACS -and click link to install it locally 2. Log into ACS and install cert into local store 3. DL cert chain from CA to ACS store 4. Tell ACS to use that cert from its store 5. restart ACS 6. log back into ACS and inst
1. User performs .1x with RADIUS 2. WLC forwards radius accounting start to NAM (along with clients IP) 3. clients NAA detects network con. & tries to connect to NAM. 4. NAS Intercepts step 3 & contacts NAM itself to see if client is in the online li
x509 cert to establish DTLS capwap control tunnel. It can be either 1. LSC 2. MIC (Mafctr installed cert) or 3. SSC

14. Steps to adding an IPS
DTLS (Datagram Transport Layer Security)
1. Create user acct. in IDS for each WLC in the viewer role 2. add the WLCs IP as an allowed host 3. Obtain the IPS TLS Fingerprint & add it to WLC 4. Enable the client exclusion policy on the WLAN 5. Set msg log level to Alerts to log IPS events
enables Identity Based Netowrking (IBN) where wlan settings are changed per-user (qos - vlan - acls - or timeouts)
1. Wireless-->AP Global Config-->enable dot1x w/ user/pass 2. Config the switch port to enable auth. to ACS/RADIUS

15. What is used for HREAP Roaming re: keying
Corrospond to top-menu GUI items (wireless - security - monitor etc)
used with PEAP for user/password authentication
WLCs create a deriviative of the PMK - called Opportunistic Key Caching (OPC) for fast-roaming among HREAPs in the same HREAP group.
puts the ap and client through tests to isolate connection issues. This disables the wlan while doing this. Can be used to diagnose .1x auth - .11 association etc. if using ccxv5

16. Difference between mobility list and mobility group
a mobility list can contain multiple mobility groups
Proactive Key Caching (PKC) or CCKM
same as steps to roaming in non-802.1R except: skips PMK negotiation & piggybacks PTK & QoS with the 802.11 authentication & association messages
1. CAPWAP 2. NMSP (network mobility services) 3. SNMP 4. SOAP/XML

17. What is HREAP Local Auth limitation
1. Create user acct. in IDS for each WLC in the viewer role 2. add the WLCs IP as an allowed host 3. Obtain the IPS TLS Fingerprint & add it to WLC 4. Enable the client exclusion policy on the WLAN 5. Set msg log level to Alerts to log IPS events
mping = tests intercontroller control traffic. eping = tests intercontroller data traffic (EoIP)
100 local accounts max
Controll is (mgmnt) not data. To encrypt data: check data encryption under advanced tab of ap config

18. RADIUS UDP Ports
1 AP per 15 -000 sq. feet.
1812 - Authentication 1813 - Authorization
puts the ap and client through tests to isolate connection issues. This disables the wlan while doing this. Can be used to diagnose .1x auth - .11 association etc. if using ccxv5
used with PEAP for user/password authentication

19. IAPP roaming protocol
WLC generates a Message Integrity Check Information Element (MIC IE) - which includes a sequence # - and aps add it to each mgmt frame. Clients ignore this IE - as they do not understand it.
1. User performs .1x with RADIUS 2. WLC forwards radius accounting start to NAM (along with clients IP) 3. clients NAA detects network con. & tries to connect to NAM. 4. NAS Intercepts step 3 & contacts NAM itself to see if client is in the online li
grouping WLCs or map areas - so Lobby ambassadors can create guest accounts only on certain wlcs
Inter Access Point Protocol uses UDP between aps to exchange information about new aps (announce) in the area and handoffs that have occurred when client roams

20. Describe AP Assisted Roaming
Inter Access Point Protocol uses UDP between aps to exchange information about new aps (announce) in the area and handoffs that have occurred when client roams
1. udp 16666 for control traffic 2. IP Protocol 97 (EoIP) for client data traffic
Clients send info re: previously associated aps to current ap - so it can use this information to inform current clients about neighboring aps. Requires CCXv2
1. Scanning - for other aps in the area 2. exchanging 802.11 auth messages (first from client then from ap) w/ the target ap 3. exchanging re-association messages with target ap 4. dot1x master key (PMK) negotiation 5. key derivation - 4way handshake

21. What must be configured the same for an HREAP not to disconnect clients when failing over (or back) to a WLC
1. config mobility list to support anchor & foreign wlcs (using different mob. groups on ea. to keep auth. seperate between anchor & foreigns) 2. Map the guest wlan on foreign wlc to either mgmt int. or fake dynamic int. (ie dynamic int tied to a vla
UDP 5246 & 5247
MFP
1. VLAN Mapping 2. WLAN Ordering 3. WLAN Configuration

22. Protocols used in wIPS
1. LEAP 2. EAP-FAST
MFP
1. CAPWAP 2. NMSP (network mobility services) 3. SNMP 4. SOAP/XML
DTLS (Datagram Transport Layer Security)

23. What is Conditional Web Redirect
after .1x authentication user is forwarded to a splash page. This is done via RADIUS attribute
1. client begins in Quarenteen vlan & NAA sends posture assesment to NAS 2. assesment is verified against policies in NAM 3. If in compliance - client is moved to access vlan. If not - NAS sends remediation info to client 4 NAA guides user through re
used with PEAP for user/password authentication
1. Log into cert. server - from ACS -and click link to install it locally 2. Log into ACS and install cert into local store 3. DL cert chain from CA to ACS store 4. Tell ACS to use that cert from its store 5. restart ACS 6. log back into ACS and inst

24. WLC Tacacs+ roles
1. Off (default) - moves down list and uses next server indefinately. 2. Passive -- Upon failure - server is marked as inactive for (300 seconds) then is put back in list and tried again (if its highest priority). 3. Active -- Actively probes failed
Corrospond to top-menu GUI items (wireless - security - monitor etc)
-150ms
after .1x authentication user is forwarded to a splash page. This is done via RADIUS attribute

25. What does a wired IPS do compared to the WLC IDS
used with PEAP for user/password authentication
mititgate non-802.11 attacks
1. CBC-DES 2. CFB-AES-128
Inter Access Point Protocol uses UDP between aps to exchange information about new aps (announce) in the area and handoffs that have occurred when client roams

26. How does client MFP work
Clients download a key for their wlan - after auth - so they can understand that IE in the mgmt frame
based on auth. group -1. vlan 2. qos 3. acl 4. tunnel attributes
1. Log into cert. server - from ACS -and click link to install it locally 2. Log into ACS and install cert into local store 3. DL cert chain from CA to ACS store 4. Tell ACS to use that cert from its store 5. restart ACS 6. log back into ACS and inst
Clients send info re: previously associated aps to current ap - so it can use this information to inform current clients about neighboring aps. Requires CCXv2

27. Whats in CCXv4?
Asymetric (public & Private key-pair)
MFP-1 protects infrastructure from management frame attacks (ie aps only). MFP-2 Protects both infrastructure & clients
Sends the PMK to all WLCs that the client can roam to.
peap-mschapv2 - eap-tls - mfp-v1 - nac

28. Is data encrypted over a capwap tunnel?
1. CAPWAP 2. NMSP (network mobility services) 3. SNMP 4. SOAP/XML
uses TLS to secure other eap methods like certs - user/pass - smart cards. Identifies itself to client with certificate. Utilizes: fast reconnect (faster roaming w/ key caching) and server authentication
after authentication - the client & radius server cache session keys for a configurable amount of time
Controll is (mgmnt) not data. To encrypt data: check data encryption under advanced tab of ap config

29. Will foreign/anchor communication work through PAT?
no
is provided to clients as they associate - including neighbor ap info like channel - rssi etc.
1. RSSI 2. SNR 3. Load-Ballancing
Nac Guest Server - used for provisioning guest accts - detailed usage reporting - delivery of creds via emai/sms -

30. What kind of local 802.1x auth. does HREAP support
1. on NAS create an oob profile for the WLC 2. Create a new device in NAM - specifying the WLC mgmt ip 3. device mgmnt-->NAS & add the NAS ip as an oob virt. gateway 4. still on nams nas config page - enter the nas trusted int. ip & untrusted int vla
1. LEAP 2. EAP-FAST
1. WLC must be defined as a VPN Conentrator - in the NAC config. 2. WLC must be configd to send RADIUS acct. to NAC
RSN Tag. Auth Key mgmt will show PSK - or WPA (for 802.1x) Stands for Robust Security Network

31. AAA override
1. Interfac Configuration --> RADIUS (IETF) --> check 64 (Tunnel Type) - 65 (Tunnel Medium Type) - 81 (Tunnel Private-group-id) 2. Navigate to Group Setup and enable the checkboxes for the previous attributes - where 64=VLAN - 65=802 - 81=<Vlan_tag>
enables Identity Based Netowrking (IBN) where wlan settings are changed per-user (qos - vlan - acls - or timeouts)
peap-mschapv2 - eap-tls - mfp-v1 - nac
300ms

32. Steps to config. .1x for AP to WLC connections
1. Wireless-->AP Global Config-->enable dot1x w/ user/pass 2. Config the switch port to enable auth. to ACS/RADIUS
300ms
grouping WLCs or map areas - so Lobby ambassadors can create guest accounts only on certain wlcs
1. VLAN Mapping 2. WLAN Ordering 3. WLAN Configuration

33. 3 modes of radius fallback
Nac Guest Server - used for provisioning guest accts - detailed usage reporting - delivery of creds via emai/sms -
1. PMK is only valid for 1 hour -- CCKM creates a main key & derives secondary keys. These secondary keys are sent to all wlc/aps.
ACL - or Interface-name configured in ACS -1. Interface Configuration --> RADIUS (Cisco Airspace) and check off: Air-Qos-Level - Aire-DSCP - Aire-802.1p tag - Aire-Interface-name - Air-ACL-Name
1. Off (default) - moves down list and uses next server indefinately. 2. Passive -- Upon failure - server is marked as inactive for (300 seconds) then is put back in list and tried again (if its highest priority). 3. Active -- Actively probes failed

34. How does CCKM simplify PMK Caching
Allows intel clients to request a neighbor list at will.
1. config mobility list to support anchor & foreign wlcs (using different mob. groups on ea. to keep auth. seperate between anchor & foreigns) 2. Map the guest wlan on foreign wlc to either mgmt int. or fake dynamic int. (ie dynamic int tied to a vla
WLC can detect 802.11 attacks - but not other attacks from valid wireless clients.
1. PMK is only valid for 1 hour -- CCKM creates a main key & derives secondary keys. These secondary keys are sent to all wlc/aps.

35. How does the Nac Appliance Agent (NAA) work cohesively with 802.1x
peap-mschapv2 - eap-tls - mfp-v1 - nac
1. Captive Portal 2. NAA (agent installed on windows); auth twice (1 to radius 2 to nac) 3. NAA w/ SSO - user authss once. & wlc auths to nac on their behalf.
1 AP per 15 -000 sq. feet.
It handles .1x & NAC auth. with Single Sign on. WLC forwards RADIUS accounting messages (of EAPOL Success) to the NAC upon login - authing the client to nac - & then it goes through posturing

36. Eap process/messages
DTLS (Datagram Transport Layer Security)
used with PEAP for user/password authentication
uses TLS to secure other eap methods like certs - user/pass - smart cards. Identifies itself to client with certificate. Utilizes: fast reconnect (faster roaming w/ key caching) and server authentication
1. client -> authenticator: eapol_start 2. authenticator -> client: eap request/identity 3. client -> authenticator: eap response/identity 4. authenticator -> aaa: radius access request 5. aaa -> client: eap-tls handshake 6.aaa -> authenticator: radi

37. What does FIPS-2 require for WLC to RADIUS communications
AES-Key Wrap
WLCs create a deriviative of the PMK - called Opportunistic Key Caching (OPC) for fast-roaming among HREAPs in the same HREAP group.
1. NAC Guest Server (NGS) - Like a RADIUS server when people can create guest accounts 2. Nac Manager (NAM) - Centrilized server for creating policies & profiles that determine network access. 3. Network Access Server (NAS) - The device which control
Proactive Key Caching (PKC) or CCKM

38. 3 categories of segmented traffic
Corrospond to top-menu GUI items (wireless - security - monitor etc)
1. HMAC-MD5 2. HMAC-SHA
mititgate non-802.11 attacks
1. application type 2. security capabilities 3. QoS policy

39. What are the 4 main components of NGS re: guests
1. Guest User 2. Sponsor 3. Network Enforcement Device (ie wlc) 4. NGS Server itself
AES-Key Wrap
1. CBC-DES 2. CFB-AES-128
Only when all the RADIUS servers defined globally are unreachable. (ie. even if not called out under WLAN-->AAA - the global RADIUS servers will be used instead of local profile)

40. Steps to roaming in 802.1R
same as steps to roaming in non-802.1R except: skips PMK negotiation & piggybacks PTK & QoS with the 802.11 authentication & association messages
1. NAC Guest Server (NGS) - Like a RADIUS server when people can create guest accounts 2. Nac Manager (NAM) - Centrilized server for creating policies & profiles that determine network access. 3. Network Access Server (NAS) - The device which control
1. Log into cert. server - from ACS -and click link to install it locally 2. Log into ACS and install cert into local store 3. DL cert chain from CA to ACS store 4. Tell ACS to use that cert from its store 5. restart ACS 6. log back into ACS and inst
1. VLAN Mapping 2. WLAN Ordering 3. WLAN Configuration

41. What is 802.11w?
Asymetric (public & Private key-pair)
a mobility list can contain multiple mobility groups
MFP
Proactive Key Caching (PKC) or CCKM

42. How is the CAPWAP tunnel between AP & WLC encrypted
ACL - or Interface-name configured in ACS -1. Interface Configuration --> RADIUS (Cisco Airspace) and check off: Air-Qos-Level - Aire-DSCP - Aire-802.1p tag - Aire-Interface-name - Air-ACL-Name
1. Integrated -- wIPS monitor mode aps are part of client-serving infrastructure 2. Overlay -- wIPS aps - WCS & WLCs are totally seperate
1. application type 2. security capabilities 3. QoS policy
x509v3 certificate

43. What are mping and eping used for from the wlc cli
1. Guest User 2. Sponsor 3. Network Enforcement Device (ie wlc) 4. NGS Server itself
mping = tests intercontroller control traffic. eping = tests intercontroller data traffic (EoIP)
WLCs create a deriviative of the PMK - called Opportunistic Key Caching (OPC) for fast-roaming among HREAPs in the same HREAP group.
AES-Key Wrap

44. What is needed to use Locally Significat Certificates (LSC) when establishing tunnel from OEAP to WLC
1. Captive Portal 2. NAA (agent installed on windows); auth twice (1 to radius 2 to nac) 3. NAA w/ SSO - user authss once. & wlc auths to nac on their behalf.
PKI
1. application type 2. security capabilities 3. QoS policy
ACL - or Interface-name configured in ACS -1. Interface Configuration --> RADIUS (Cisco Airspace) and check off: Air-Qos-Level - Aire-DSCP - Aire-802.1p tag - Aire-Interface-name - Air-ACL-Name

45. Why is fast secure roaming used
Sends RADIUS packets from a dynamic interface instead of the WLC Mgmt interface address
is provided to clients as they associate - including neighbor ap info like channel - rssi etc.
Does not require re-authentication when a client roams - in an 802.1x/WPA2 environment
switchport mode access - dot1x pae authenticator - dot1x port-control auto

46. When submitting a CSR from ACS
what must you ensure -1.Exportable 2.Server Auth Cert 3.Store cert in local cert store
1. Temporal Key for Unicast 2. Key Confirmation Key (KCK) - used for group handshakes 3. Key Encryption Key (KEK) - for encrypting the group encyrption key used to derive the braodcast/multicast keys.
checking allow aaa over-ride in the wlan-->advanced.
WLC sends a roam-request to a client when it can better serve that client on a different AP. Client can accept or ignore. CCXv4+

47. How is encryption established between OEAP & Anchor WLC
Inter Access Point Protocol uses UDP between aps to exchange information about new aps (announce) in the area and handoffs that have occurred when client roams
1. RSSI 2. Duration 3. Client Count 4. No encryption 5. Managed SSID (ie UNLV) 6. SSID
on the WLC -1. Configure an Access vlan & check the quarentine vlan - giving it the quarentine vlan tag 2. on wired net connect the Quarenteen vlan to the untrusted NAS interface. 3. Connect the access vlan to the trusted int. on the nas 4. config sn
x509 cert to establish DTLS capwap control tunnel. It can be either 1. LSC 2. MIC (Mafctr installed cert) or 3. SSC

48. Things to Enable in ACS (Global Authentication Page) for PEAP support
1. Allow EAP-MSCHAPv2 2. Allow EAP-GTC 3. Check Posture Validation when doing NAC
1. udp 16666 for control traffic 2. IP Protocol 97 (EoIP) for client data traffic
WLC generates a Message Integrity Check Information Element (MIC IE) - which includes a sequence # - and aps add it to each mgmt frame. Clients ignore this IE - as they do not understand it.
1. WLC must be defined as a VPN Conentrator - in the NAC config. 2. WLC must be configd to send RADIUS acct. to NAC

49. Directed Roam Request
HTTPS
It handles .1x & NAC auth. with Single Sign on. WLC forwards RADIUS accounting messages (of EAPOL Success) to the NAC upon login - authing the client to nac - & then it goes through posturing
WLC sends a roam-request to a client when it can better serve that client on a different AP. Client can accept or ignore. CCXv4+
Does not require re-authentication when a client roams - in an 802.1x/WPA2 environment

50. Vlan pooling
based on auth. group -1. vlan 2. qos 3. acl 4. tunnel attributes
1. RSSI 2. Duration 3. Client Count 4. No encryption 5. Managed SSID (ie UNLV) 6. SSID
checking allow aaa over-ride in the wlan-->advanced.
assigning multiple vlans to single wlan - and users are dynamically mapped to one of the vlans in round-robin