Building an Ultra-Broadband Wireless Network

With every new generation of Wi-Fi, the data rate of the air interface on a wireless network greatly increases. For example, with Wi-Fi 6, the transmission rate of a single AP increases to nearly 10 Gbit/s. Such APs can be used to deploy an ultra-broadband wireless network, which can be built using either of the following networking architectures:

• • Wireless access controller (WAC) + Fit AP: also known as centralized networking. This architecture reduces AP management and maintenance costs and implements large-scale wireless network deployment.
• • Wired and wireless convergence: also known as the integrated WAC networking. This architecture improves management, forwarding, and maintenance efficiency and makes service policies more flexible.
• 1. WAC+Fit AP networking architecture

In this networking architecture, a WAC centrally manages Fit APs through the Control And Provisioning of Wireless Access Points (CAPWAP) protocol, achieving unified wireless service

TABLE 4.10 Device port models for different user scales

management. Fit APs provide radio signals for STAs to access a wireless network, and provide almost no management or control capabilities at all.

The WAC+Fit AP networking architecture is applicable to large- and medium-sized campus networks. On such a network, a WAC can be deployed at either the aggregation or core layer, depending on the wireless network capacity and locations of Fit APs at the access layer. For reliability purposes, deploying the WAC at the core layer is considered best practice. The WAC is responsible for service control such as configuration delivery and upgrade management for all Fit APs, which are also plug-and-play, greatly reducing WLAN management, control, and maintenance costs.

WACs provide the same features in both in-path and off-path deployments. Figure 4.30 shows the latter deployment mode for

WACs connecting to core switches. WACs can also connect in off-path mode to aggregation switches.

In off-path networking, WACs manage APs over CAPWAP tunnels, whereas data flows can either travel through the WACs over CAPWAP tunnels or bypass the WACs by being directly forwarded by core switches to the upper-layer network. This networking mode facilitates the deployment of new WACs on live networks. These WACs are connected to idle ports on core or aggregation switches, without affecting the original physical connections or services. In addition, the off-path networking applies when we need to centrally deploy WACs to manage sparsely distributed APs that are within the management scope of switches connected to the WACs.

Figure 4.31 shows the WAC in-path deployment, where WACs are located in the data forwarding path between downstream APs and upstream devices such as core switches or egress routers.

In the in-path networking mode, WACs also act as switches to process all data packets, facilitating centralized management of user data. However, if a large amount of user data is involved in this networking mode, the data processing capability of the WACs will be affected. Therefore, it is considered best practice to deploy WACs at or below the core layer. Such characteristics make in-path networking applicable to small- and medium-sized campus networks where APs are densely deployed. Due to restrictions of the in-path deployment locations, off-path networking is widely used on live networks.

2. Wired and wireless convergence networking architecture

Huawei’s agile switches are able to implement wired and wireless convergence. That is, in addition to processing wired packets, the agile switches can identify and process CAPWAP packets. They can centrally manage wired and wireless service traffic in a wired and wireless convergence topology, such as that shown in Figure 4.32. Figure 4.33 shows the networking architecture for wired and wireless convergence.

Wired and wireless convergence brings the following benefits to customers:

a. Improved forwarding capacity: Traditional campus switches cannot parse wireless packets and therefore require the WAC off-path deployment. The downside of this deployment mode is that wireless service traffic arriving at switches is forwarded to WACs and

FIGURE 4.33 Wired and wireless convergence networking architecture.

then forwarded back to the switches, causing a longer delay. In addition, the overall forwarding capacity for wireless service traffic depends on the forwarding performance of WACs. With wired and wireless convergence technology, Ethernet Network Processor (ENP) cards on agile switches are able to decapsulate and forward wireless packets together with wired packets. This simplifies the forwarding path and eliminates forwarding bottlenecks.

b. Unified management of devices and user policies: The management plane of WACs is independent from that of switches, complicating network management and maintenance. Wired and wireless convergence technology centralizes management and control points on an agile switch, allowing for unified management of wired and wireless users.

c. High reliability: In a traditional solution where two standalone WACs work in 1 +1 backup mode, an additional channel must be established between them for data synchronization. This is normally achieved using technologies such as Virtual Router Redundancy Protocol (VRRP) and Bidirectional Forwarding Detection (BFD). However, synchronizing data between different devices in this way compromises real-time performance and reliability. The wired and wireless convergence solution overcomes these shortcomings by using reliability technologies (stacking and Eth-Trunk) of switches to implement device-level and link- level redundancy. In this way, the main processing units (MPUs) of switches centrally control wireless data, while ENP cards of switches automatically synchronize wireless data to each other in real time, without the need to establish additional channels. Therefore, real-time performance and reliability are improved.

d. Flexible capacity expansion: As wireless terminals are widely used, wireless services need to be added to the legacy networks that currently provide only wired services. Huawei agile switches are an ideal choice due to their ENP cards being able to implement wired and wireless convergence, avoiding great adjustments or changes to the physical network. Additionally, the ENP cards can be easily expanded to meet requirements of the increasing wireless users and wireless service volume.

e. Fast wireless roaming: When a switch with ENP cards functions as a WAC, APs connected to its different ENP cards are centrally managed and controlled by the switch MPUs. So, when STAs roam between these APs, they actually roam on the same WAC. In contrast, if STAs roam between APs connected to different standalone WACs, they roam between WACs. In this way, the integrated WAC solution provides faster wireless roaming and shorter forwarding paths.

3. Deployment suggestions for ultra-broadband wireless networks

The air interface technology is critical to ultra-broadband wireless networks. And next-generation Wi-Fi 6 APs can be employed to improve wireless coverage and throughput capabilities, so as to implement ultra-broadband forwarding. For example, a Wi-Fi 6 AP can provide a maximum rate of 9.6 Gbit/s on a single 5 GHz radio. When higher bandwidth is required, APs with dual 5 GHz radios can be deployed, with rates of up to 19.2 Gbit/s delivered by a single AP. The APs use the Eth-Trunk technology to bundle two 10GE wired uplinks into a 20GE uplink. Additionally, 10GE access switches are deployed to implement ultra-broadband networking of the wireless access layer. Different AP models are better suited to different scenarios, for example:

a. In high-density stadiums, APs with directional antennas are preferred, as they provide centralized coverage and reduce interference.

b. In classrooms, APs with triple radios are preferred, as they provide higher access capacity.

c. In hotels, agile distributed APs are preferred. An independent remote unit is deployed in each room, as they provide ubiquitous coverage and avoid mutual interference.

On a campus wireless network, ultra-broadband forwarding must be achieved by not only a single AP but also the overall wireless network. For example, AP position planning and intelligent radio calibration need to be performed to maximize the coverage while minimizing interference.

For wireless networking, the wired and wireless convergence architecture is the best choice, with core switches implementing integrated WAC functions. This prevents traffic from being forwarded to standalone WACs. The advantage of standalone WAC networking is that it features a strong control capability. However, it delivers a relatively low forwarding capability (only 40 or 100 Gbit/s). Therefore, the standalone WAC networking is applicable to scenarios that do not require high wireless network forwarding capabilities. However, there is a growing demand for network bandwidth as the Wi-Fi 6 standard is popularized, and bandwidth-hungry services, such as campus augmented reality, VR, and 8K high definition video, are widely being put into commercial use. Huawei core switches integrated with WAC functions are suitable for future ultra-broadband campus networks due to their wireless management capabilities and ultra-broadband forwarding capacities of 50 Tbit/s or higher.