Legacy Open Mesh: Placing Nodes and Scaling the Network

Topic

This article discusses node placement and scaling for Open Mesh Access Points.

Environment

• Open Mesh Access Points

Description

The number of nodes needed, and the placement of those nodes depends on a variety of environmental conditions.

Determining the placement and number of nodes needed

Environmental variables

The number of nodes you require depends on the following factors:

• the size of the area you need to cover
• the number of walls and floors you need to penetrate with mesh
• the material comprising the walls and floors
• the amount of interference in your environment
• the number of simultaneous users expected on the network

While every installation is different, you shouldn't generally exceed these parameters when planning:

Evaluating signal strength

In CloudTrax, you can see each device's speed and signal strength (both of which decrease over distance and through walls and floors). Look for signal strength (or RSSI) to be no higher than -65, where -30 to -50 is desirable. You can add, remove, or reposition nodes at any time.

Users per node

For optimal user experience, aim for no more than 20-50 users per node. The maximum number of users will vary based on your network environment, ISP connection, and bandwidth to each client device.

Transmit power

With any model, it is possible to overpower dense indoor networks. However, you can turn the transmit power down through CloudTrax if you experience symptoms such as interference or dropped connections. Setting TX Power to 19 or 21 dBm typically resolves these issues.

Testing the environment

For large installs, check your environment with CloudTrax and two or three nodes before buying all of the nodes. You'll be able to see the range and how many walls and floors you can expect to transmit through in your specific environment. Nodes transmit in a spherical pattern—up, down and side to side—so there's no need to “aim” signals.

Here are some guidelines to help plan how many nodes you need for your installation.

Indoor vs. outdoor node installations

Where possible, install your nodes indoors. In addition to costing more to install, outdoor nodes:

• often require an electrician to install power
• may involve getting up on ladders or rooftops
• need installation of long Ethernet cables
• may be unsightly and often violate apartment/ condo CC&Rs
• take your strongest signals outdoors, the opposite of what you generally want

Sample node setups

Hotels and apartments: You will typically need one node for every four to six hotel rooms or apartments (this will vary depending upon the type of construction and layout).

• In single-story, single-row concrete, brick, or stone buildings, you may need one node in every second or third unit.
• In wood-frame multistory buildings with interior hallways and small rooms, one node for every six or seven rooms may be sufficient if placed in a central hall.
• When installing multistory buildings, a best practice is to place nodes on every second floor for both concrete and wood buildings.
• Copper ceilings, steel plating, cement, and adobe-type materials may limit (and even eliminate) signal transmission between floors.

Coffee shops and restaurants: One well-placed node can usually cover an entire coffee shop. For restaurants or large coffee shops, you may need two or three nodes, especially if you want to include outdoor seating areas.

Small and medium-sized businesses: One well-placed node can usually cover a small retail shop. For larger spaces, use the numbers in the table above to plan the number of access points based on the number of walls to penetrate.

Residential neighborhoods: In residential areas, a best practice is to ensure that each house has at least one node. If the houses are large, you can add multiple nodes to provide better coverage in every room.

• Wherever possible, place nodes near windows or exterior walls with a direct line of sight to the nodes in other houses.
• Placing some nodes outside may help extend coverage more efficiently.

Determining gateway locations

Gateway users on mesh networks will lose half (or more) of their maximum speed for every hop away from the gateway. As a best practice, place the gateways as central to the coverage area as possible.

Figure 1: Speed degradation over multiple hops to the gateway

By moving the gateway from one end to the center, you can improve the maximum potential speed on the outer reaches of the network by a multiple of four.

Figure 2: Optimal gateway placement

Since your repeaters' speed will operate at maximum speed if they have a direct (or single-hop) connection to the gateway, put your DSL/cable/fiber connection as close to the middle of the coverage area as possible.

All of your nodes should have an RSSI of at least -70 (the closer to zero, the stronger the signal) to one or more nodes. If not, try repositioning them closer or add more nodes.

Scaling your network

CloudTrax networks are highly scalable. To build large-scale networks, add additional gateways and repeaters according to the guidelines above.

• There is virtually no limit to the number of gateways and repeaters you can have on a single network, although we recommend 200 or fewer nodes for report readability.
• More extensive networks can be broken up into discrete zones under the same login.

Figure 3: Network scalability

Adding additional gateways

There are two primary ways to add additional gateways:

• Multiple DSLs (cable modems, etc.)
  • Let you avoid running Ethernet cabling
  • Provide built-in failover (if one DSL goes down, your network will switch-over to the others)
  • Somewhat slower than the Ethernet method
  • May cost more due to multiple DSL connections
• A switch with Ethernet cables distributing gateways evenly through your network.
  • Faster than multiple DSLs
  • Reduced ongoing cost
  • You may need to run Ethernet cabling

Additional tips

Here are some additional network planning suggestions:

• Ensure the nodes' signal edges overlap so that each node can talk to at least one (and preferably two) other nodes with good signal quality.

• Don't under-install. Building redundancy into the network by having extra nodes lets CloudTrax's self-healing, self-configuring mesh protocol to keep users connected and minimize outages.

• To avoid bottlenecks, don't run more than five repeaters off of any single gateway.

• Think vertically in multistory buildings. If you have two or three floors to cover, place the nodes on the middle floor so they can provide coverage where they can provide coverage both above and below.

• Use straight lines when broadcasting through walls and floors. The less material the wireless signal must penetrate, the stronger the signal.

• If you are installing in an apartment complex or hotel with internal hallways and no in-room cat 5/6 Ethernet cabling, consider placing most nodes in the hallways.

  • As this is shared space, you'll have access to them without disturbing residents.

  • The nodes can see each other without having to go through as many walls, maximizing the signal between the routers and minimizes potential “hops” and low signal quality.

  • Add additional nodes as needed (typically in larger units) to boost signals in specific areas.

Figure 4: Suggested node placement in larger units

• If you are installing a building that has cat5/6 Ethernet cabling to each room, consider using the indoor Ethernet enclosure to add gateways to as many rooms as needed. In this scenario, you could do without repeaters completely, maximizing your network performance.

• If there is no power outlet where you want to place a node, you can power it through an Ethernet cable (power over Ethernet, or PoE).

  • Passive PoE can power any OM-Series device.

  • Only the OM2P-HS, OM5P-AC and MR1750 devices are compatible with PoE switches using 802.3af standard PoE.

  • Two enclosures—the outdoor enclosure and indoor Ethernet enclosure—are best used with PoE. While it is optional in the indoor ceiling enclosure, PoE is not recommended for the indoor wall plug enclosure.