Multi-AP Specification v2.0
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Used with the permission of Wi-Fi Alliance under the terms as stated in this document.
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19 Traffic Separation
19.1 Traffic Separation in Multi-AP Network
19.1.1 Traffic Separation Overview (Informative)
This informative description of traffic separation relies on terms defined in section 3.1.
A Multi-AP Controller is able to configure multiple fronthaul SSIDs in a Multi-AP network. A Multi-AP Profile-2 Network
Segment supports traffic separation for each fronthaul SSIDs using a unique VLAN. The traffic belonging to each VLAN is
distinguished using an 802.1Q C-TAG with a unique VLAN ID, or the lack of thereof.
The rules defined in section 19.1.3 ensure that traffic generated within a Multi-AP network is clearly identifiable as
belonging to one SSID. Traffic generated outside of a Multi-AP network is tagged with a VLAN ID (or untagged as
appropriate) prior to ingressing the Multi-AP network by means not defined in this specification and is expected to be
identified as belonging to an SSID.
A Multi-AP device is a layer-2 (Link Layer) logical device that can be embedded into a more complex physical device
(e.g., a router, or a gateway) that implements both a Multi-AP Agent as well as other, above layer-2, functionalities. Often
in this case, traffic generated outside of the network (e.g., ingressing thru the WAN interface) is classified by the
gateway/routing subsystem and tagged (if needed) before being forwarded to the Multi-AP device subsystem. The
abstract/logical interface between the Multi-AP subsystem and the rest of the device is considered a Multi-AP Logical
Ethernet Interface as per the definition in section 3.1.3 and the rules in section 19.1.3.
If Traffic Separation is not configured on a Multi-AP Agent that implements Profile-2, the Multi-AP Agent might behave in a
transparent manner to VLAN tags applied by other entities.
A Multi-AP Controller configures SSID to VLAN ID mapping in a Traffic Separation Policy. Each mapping from one or
many SSIDs to one VLAN ID is indicated in a Traffic Separation Policy TLV. The Multi-AP Controller distributes the Traffic
Separation Policy to all Multi-AP Agents. It is recommended that a Multi-AP Controller provides each Multi-AP Agent with
a complete list of VLAN ID to SSID mappings, including those VIDs that are mapped to SSIDs that are not configured on a
given Multi-AP Agent, to enable that traffic on all VIDs is forwarded over backhaul links. Multi-AP Agents report to the
Multi-AP Controller the maximum number of VIDs they are able to configure in the Profile-2 AP Capability TLV. A
Controller that intends to use more VIDs than those supported on some of the Multi-AP Agents it manages, may re-
arrange the topology in such a way that traffic for all VIDs downstream of a Multi-AP Agent can be forwarded by such
Agent.
For each Ingress Packet, a Multi-AP Agent adds an 802.1Q C-TAG with a VLAN ID as specified in a Traffic Separation
Policy.
For each Egress Packet, a Multi-AP Agent removes any 802.1Q C-TAG.
For a packet to be transmitted on a Multi-AP Logical Ethernet Interface, if the VLAN ID in the 802.1Q C-TAG is set to one
of the Secondary VLAN IDs, a Multi-AP Agent maintains the 802.1Q C-TAG on those packets.
Multi-AP IEEE 1905.1 management frames are carried in the Primary Network.
A Default 802.1Q Settings TLV identifies a Primary VLAN ID for tagging packets on the Primary Network.
Traffic separation is not supported across a Multi-AP Agent that implements Profile-1. Therefore, a Multi-AP Controller
should not configure any SSID that is mapped to a Secondary VLAN ID on any Multi-AP Agent that implements Profile-1
or on any Multi-AP Agent that is downstream of a Multi-AP Agent that implements Profile-1. If the location of the WAN
connection in a network managed by a Multi-AP Controller changes (e.g., in order to use a backup WAN connection in the
event the main WAN connection fails), the portions of the network where traffic separation is possible may change and the
Multi-AP Controller may need to reconfigure the entire network accordingly, including Secondary SSIDs and VLAN(s).
A Multi-AP Controller that reconfigures VLAN(s) in the entire Multi-AP Profile-2 Network Segment may reconfigure the
traffic separation policy on the Multi-AP Agents, starting from those at the very end of the data-plane tree topology and
finishing at the data-plane root. Failing to do so may result in the inability to deliver reconfiguration CMDUs to downstream
Multi-AP Agents due to Primary VLAN ID mismatch. During VLAN reconfiguration data traffic loss may occur.
