Using Ethernet over GRE to Enable Layer 2 Communication Between an AC and a Wireless Gateway
To enable users to access the network anywhere, anytime, wireless city projects are being constructed in an increasing number of places. In the Wi-Fi user access solution, the Ethernet over GRE technology can enable APs to encapsulate access user traffic as Ethernet packets into GRE packets and then these packets are transparently transmitted over a GRE tunnel to a WLAN GW. After the WLAN GW receives these user packets, it removes the GRE header and then assigns IP addresses and provides Internet access for users.
In this scenario, an S5720-HI, S5730-HI, and S6720-HI functions as the AC to provide AP management and data forwarding.
Figure 1 shows typical wireless user access networking in a wireless city project. APs provide wireless user access; the AC provides AP access and user authentication; the WLAN GW functions as a user gateway to provide functions including IP address assignment and Internet access. In a traditional solution, APs can establish a GRE tunnel with a WLAN GW for wireless user access. This solution applies to small networks. When there are many APs, the number of GRE tunnels established on a WLAN GW may exceed the threshold configured on this WLAN GW. Additionally, GRE tunnels on a WLAN GW are dynamically created based on user traffic. If a large number of GRE tunnels are frequently established and deleted, a lot of resources on this WLAN GW will be consumed, affecting system performance.
To address this problem, a Control and Provisioning of Wireless Access Points (CAPWAP) tunnel can be established between AP and AC and a GRE tunnel can be established between AC and WLAN GW so that user traffic can reach the AC over the CAPWAP tunnel and then reach the WLAN GW over the GRE tunnel. In this scenario, only one GRE tunnel needs to be created on the WLAN GW, greatly reducing the number of GRE tunnels and saving system resources. This solution requires the AC to support the Ethernet over GRE function. Huawei S series switches support the Ethernet over GRE function and can function as the AC to implement Layer 2 communication between the AC and a WLAN GW.