Although we know that there are two network topologies to choose from in wireless LANs, Ad Hoc and Infrastructure, the peer-to-peer Ad Hoc structure belongs to point-to-point connections and has low connection performance. Therefore, this wireless network structure is rarely used in enterprise networks, except for wireless networks with only a few users. In addition, in enterprise networks, wireless networks are generally used as a supplement to wired networks and connected to wired networks, rather than being used separately. The wireless network section is usually used for temporary networks such as conference rooms and locations such as halls and squares where wiring is difficult. This example will introduce a design method for office wireless LAN architecture with multiple wireless APs widely used in enterprises.
[Example Explanation] There is a company whose office is an old-fashioned building. In order to avoid rewiring, they want to use WLAN wireless LAN cabling. The number of office users is around 30, and two IEEE 802.11g standard wireless APs are prepared. In addition, the wireless network needs to be interconnected with the existing wired network.
1. Network requirements
All users of this office can connect to wired networks through wireless APs without any conflicts.
The load of two wireless APs should be relatively balanced to avoid performance bottlenecks.
All wireless network users can access the Internet through the broadband router in the wired network.
2. Design concept
This type of network structure is actually designed very simply, with the following basic idea:
(1) Install two wireless APs in appropriate locations in the office, while ensuring that the two wireless APs can cover the corresponding wireless network user range well in terms of distance.
(2) Connect two wireless APs to a regular port on a wired network switch through a straight through twisted pair cable, and then configure the TCP/IP protocol for each wireless user in the same way as for wired networks to achieve connection with the wired network. If a wired network is already equipped with a broadband router, wireless network users can directly use the broadband router to access the internet, but of course, it is necessary to ensure that these users are not excluded from the user exclusion range of the broadband router.
(3) The channels used for configuring two APs on a wireless AP must not overlap, and each wireless network user should choose to use the corresponding wireless AP network. Please refer to the book "Gold Medal Network Administrator (Junior) Network Construction, Configuration, and Management for Small and Medium sized Enterprises" in this series of books for details.
3. Design steps
This example only illustrates the design steps of the wireless network part, and the design of the wired network part refers to the previous examples. And the wired network part in this example is represented by the most basic network structure, which can actually be any complex network structure. Just connect the wireless AP in the wireless network to the switch (usually the core switch) in the wired network.
(1) Determine the basic location of wireless network users and divide the entire wireless network user into two areas. When dividing regions, not only should the number of network users be considered, but also the specific network application performance requirements of each user should be fully taken into account, so as to make the total bandwidth demand of users in the two regions basically consistent as much as possible.
(2) Install two IEEE 802.11g standard wireless APs in the middle positions of the two user areas, as shown in Figure 3-39.
(3) Pull out a straight through twisted pair cable from the RJ-45 LAN ports of two wireless APs to at least one regular LAN port in the aggregation layer of the wired network to achieve connection with the wired network.
The above are the design steps for the wireless LAN topology structure of the infrastructure. Below is a brief introduction to the channel configuration issues of each AP in the network.
The channel IDs of the two wireless APs configured cannot overlap. Both IEEE 802.11b and IEEE 802.11g standards, which operate in the 2.4GHz frequency band, provide 13 selectable channels, with the default being the 6th channel. In a network with a single wireless AP, you can choose freely here, but if there are other wireless APs in the wireless network, it is important to note that the frequency bands covered by the channels selected by each AP cannot overlap. Based on experience, generally within a radius of 50m, only 3 wireless APs are allowed, and the selected 3 sub channels can only be combinations of 1, 6, 11, or 2, 7, 12, or 3, 8, 13, mainly to avoid mutual interference and conflict of signals emitted by each AP