Mixed Forwarding Mode

When mixed traffic forwarding is configured in a WLAN Wireless Local Area Network. WLAN is a 802.11 standards-based LAN that the users access through a wireless connection. or downlink wired port profile, the client traffic will either be directly forwarded out of the APs uplink ports onto the access switching layer with an appropriate 802.1Q 802.1Q is an IEEE standard that enables the use of VLANs on an Ethernet network. 802.1Q supports VLAN tagging. VLAN Virtual Local Area Network. In computer networking, a single Layer 2 network may be partitioned to create multiple distinct broadcast domains, which are mutually isolated so that packets can only pass between them through one or more routers; such a domain is referred to as a Virtual Local Area Network, Virtual LAN, or VLAN. tag or encapsulated in Generic Routing Encapsulation (GRE Generic Routing Encapsulation. GRE is an IP encapsulation protocol that is used to transport packets over a network.) by the APs and tunneled to the primary gateway cluster using the following forwarding modes:

• Bridged mode: The AP will bridge the traffic when a client device is assigned a VLAN ID or name that is not present in the primary or secondary gateway cluster.

• Tunneled mode: The AP will tunnel the traffic when a client device is assigned a VLAN ID or Name that is configured in the primary or secondary gateway cluster.

When a profile configured for mixed forwarding is created and a primary cluster is selected, the VLANs present in the primary and secondary clusters are learned by the APs and are tagged in the GRE tunnels. The APs use this knowledge to determine when to bridge or tunnel clients when a VLAN is assigned.

For branch deployments using branch gateways, the AP management and bridged user VLANs are typically extended from the branch gateways to the APs and are common to both. The branch gateways provide DHCP Dynamic Host Configuration Protocol. A network protocol that enables a server to automatically assign an IP address to an IP-enabled device from a defined range of numbers configured for a given network.  services and routing for each VLAN within the branch. When no layer 3 separation exists between the APs and the gateways in a branch deployment, profiles implementing mixed traffic forwarding will always tunnel the clients. If bridge traffic forwarding is required and layer 3 separation between the APs and the branch gateways is not possible, separate profiles implementing bridge traffic forwarding must be implemented.

To support mixed forwarding, the APs management and bridged user VLANs are extended from the access switching layer to the APs uplink ports. It is recommended that dedicated VLAN IDs be used for bridged and tunneled clients, and the VLANs must not overlap. As a recommended best practice, only the AP management and bridged user VLANs should be extended to your APs.

For example, in a typical mixed WLAN deployment below, dedicated VLANs are implemented for bridged and tunneled clients. The untagged AP management VLAN (not shown) and 802.1Q-tagged bridged user VLAN 76 is extended from the access switching layer to an AP. VLAN 73 is centralized within a cluster and is 802.1Q-tagged from the gateway to the core or aggregation switching layer. Client 1 is dynamically assigned VLAN 73 and is tunneled to the primary cluster, while client 2 is dynamically assigned VLAN 76 and is locally bridged by the APs.

Figure 1   Mixed Forwarding Deployment