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Dynamic Segmentation with Tunneled Node and User Roles

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Dynamic Segmentation with Tunneled Node and User Roles

A university campus has 15,000 students and 3,000 staff. They are deploying Aruba CX switches with Dynamic Segmentation and Aruba Mobility Controllers (MM/MD) for tunneled node. Access switches are a mix of Aruba 2930F (not supporting tunneled node) and Aruba 6300M (supporting tunneled node). The goal is to assign roles based on device type and user identity: students get Internet-only access, staff get full access, and IoT devices (cameras, sensors) get restricted access to a specific VLAN. The university uses ClearPass for RADIUS and role assignment. They have a mix of wired (802.1X, MAC auth) and wireless (802.1X, PSK for IoT). The IT team wants to enforce roles consistently across wired and wireless, using tunneled node where possible. However, some older switches cannot tunnel, so they must use local VLANs and ACLs. The university also wants to ensure that if a RADIUS server fails, users still get limited access (fail-open for staff, fail-closed for students).

1. Describe how you would design the role enforcement for wired access on both 6300M (tunneled node) and 2930F (non-tunneled) switches to achieve consistent role-based access, including the use of ClearPass, Aruba roles, and ACLs. Address how to handle fail-open/fail-closed requirements.

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For consistent role enforcement across mixed switches:

6300M with tunneled node:

  • Configure the switch port as a tunneled node port, with the controller as the tunnel destination. The controller assigns roles based on ClearPass attributes (e.g., Aruba-User-Role).
  • Roles are defined on the controller with associated ACLs (e.g., student-role: deny all except Internet; staff-role: permit all; IoT-role: permit only to IoT VLAN).
  • Authentication: 802.1X for users, MAC auth for IoT. ClearPass returns role and VLAN (if needed).

2930F without tunneled node:

  • Use local VLANs and ACLs. ClearPass returns standard attributes: Tunnel-Type= VLAN, Tunnel-Medium-Type=IEEE-802, Tunnel-Private-Group-ID=VLAN ID, and Aruba-User-Role (for role-based ACLs if supported).
  • The 2930F supports downloadable ACLs (DACL) via RADIUS (Aruba-User-Role with ACL). Configure roles on the switch with matching ACLs. Ensure ACLs are consistent with controller roles.
  • For IoT devices using MAC auth, assign VLAN and ACL via ClearPass.

Fail-open/fail-closed:

  • In ClearPass, define a service failure policy: for staff (identified by AD group), if RADIUS is unreachable, return a role that allows limited access (e.g., staff-fail-open role with Internet and internal resources). For students, return a deny role (fail-closed).
  • On switches, configure RADIUS dead-server detection and a fallback VLAN/role. For 6300M, the controller can be configured with a fail-open role for staff and fail-closed for students based on the authentication request. However, if the controller itself is unreachable, the switch may use a critical VLAN. For 2930F, use the critical VLAN feature: assign a VLAN that provides limited access for staff and no access for students (e.g., a quarantine VLAN with ACL).
  • Ensure that the critical VLAN on 2930F is mapped to a role that aligns with the fail-open policy for staff. Since 2930F cannot differentiate user groups when RADIUS is down, you may need to use MAC-based fallback or a separate SSID for staff vs. students. Alternatively, use IBNS 2.0 with critical VLAN and a local role that permits only Internet; this is fail-open for all, which may violate student fail-closed. To meet the requirement, consider upgrading 2930F to 6300M or using a local ACL that denies student subnets; but without identity, it's not possible. Therefore, the design should prioritize replacing 2930F or using a separate VLAN for students with no critical VLAN (fail-closed) and staff with critical VLAN (fail-open). This requires segregating ports by user type.

In summary, use tunneled node on 6300M for dynamic role enforcement, and on 2930F use VLAN+ACL with ClearPass returning role and VLAN; for fail-open/fail-closed, leverage ClearPass service failure policies and switch critical VLANs, but acknowledge limitations on 2930F and recommend segmentation by port or upgrade.

2. How would you handle IoT devices that use PSK on wireless and MAC auth on wired, ensuring they get the correct restricted role and VLAN, while preventing them from being assigned student or staff roles?

Read the worked answer

IoT devices often lack 802.1X supplicants, so they use PSK on wireless and MAC authentication on wired. To ensure they get the correct restricted role and VLAN:

Wireless (PSK):

  • Create a separate SSID for IoT with WPA2-PSK (or WPA3-SAE transition). The PSK is unique to IoT devices.
  • On the controller, map this SSID to a specific VLAN and role (e.g., IoT-VLAN, IoT-role) statically, without involving ClearPass. This ensures IoT devices cannot be assigned student/staff roles because they never authenticate via 802.1X.
  • Alternatively, use ClearPass for MAC authentication of IoT devices on the wireless, but PSK is simpler and isolates traffic. If using ClearPass, configure the SSID for MAC auth and assign role based on device MAC in ClearPass. However, PSK is common for IoT; static role mapping is sufficient.

Wired (MAC auth):

  • Configure switch ports for MAC authentication. ClearPass receives the MAC address and looks up the device in an endpoint database (e.g., ClearPass endpoints or external source). If the MAC is known IoT, assign IoT-role and IoT-VLAN.
  • To prevent IoT devices from being assigned student/staff roles, ensure that the MAC auth service in ClearPass is separate from the 802.1X service. In the MAC auth service, only allow endpoints that are in the IoT endpoint group; deny others. This prevents a student device from spoofing a MAC and getting IoT role, but MAC spoofing is possible; use port security or profiling to mitigate.
  • Role mapping: In ClearPass, for MAC auth service, assign IoT-role only if endpoint group equals IoT; otherwise, deny. For 802.1X service, assign student/staff roles based on user credentials; MAC auth is not used there.

Consistency:

  • Ensure the IoT-role on both controller and switches has the same ACL: permit only necessary traffic (e.g., to IoT management VLAN, deny all else).
  • Use device profiling in ClearPass to identify IoT devices by MAC OUI, DHCP fingerprint, etc., and dynamically assign to IoT endpoint group. This reduces manual MAC entry.
  • For wireless PSK, the controller role is static; for wired MAC auth, ClearPass returns the role. Both should map to the same VLAN and ACL.

By segregating IoT authentication methods and using dedicated services/SSIDs, you prevent role crossover and enforce restricted access.