WIFI multi-hop mesh with Mesh Connex technology

    When building wireless networks, it is often not possible to provide a wired connection for a specific access point, and you need to configure a point-to-point wireless bridge (WDS), this technology is well studied and implemented by the majority of existing offers on the market. It is more difficult to solve the problem of building a multi-hop wifi mesh network. To facilitate this task, the entire ExtremeWireless Wing line of equipment supports Mesh Connex technology.
    The basis of Mesh Connex is the IEEE802.11s, RFC 3561 standard , as well as Extreme Networks' own designs.

    With Mesh Connex, you can successfully configure multi-hop mesh, both in static and dynamic configuration.

    - Multi-hop static Mesh Connex - infrastructure mode, can be used when building objects such as sea or airports, leisure parks, careers;
    - Multi-hop Mobile Mesh Connex - dynamic mesh, when access points are installed on moving objects (buses, cars, dump trucks ...)
    Also, both modes can be used simultaneously within the same mesh network.

    Access Points can operate as the following mesh elements:

    • MPR (Mesh Point Root) - AP with wired network access
    • MP (Mesh Point) - Fixed AP without wired network access
    • VMM (Vehicle Mobile Mounted) - AP installed on a moving object

    At the same time there are no restrictions on the number of root access points in the network; different priority levels can be assigned to different MPRs. Using the Backhaul Detection feature, the MPR checks if there is access to the wired network and redirects traffic to another root if there is any problem with the wired port. To monitor critical resources, you can configure them to check using ARP or ICMP requests, in this case, even if the wired backhaul on MPR is raised, traffic will be redirected through another MPR.

    The main difference between Mesh Connex and other technologies used to build multi-hop mesh networks is the routing protocol that calculates the optimal route between mesh nodes. Routing protocols in wireless mesh networks can be proactive or reactive.

    • Proactive - constantly updating the complete routing table, which, even with a medium-sized network, increases the service “overhead” traffic, while taking time and resources for complete convergence
    • Reactive - protocols slowly respond to changes in the network, storing routes only to neighbors, but at the same time have a higher delay when searching for a route

    Mesh Connex uses both of these approaches at the same time, in a hybrid mode. Initially, route information is collected reactively in on-demand mode, when each MP studies the route only to MPR, and then, as the network functions, the traffic delivery is optimized using proactive mode.

    In a wireless multi-hop mesh network, it often happens that even if a neighbor has a better SNR in general, the route to the root point will have worse characteristics through it, so Mesh Connex calculates routes based on the following data:

    - Link Quality - how well beacons are heard neighbor (i.e., initially the value of “predicted” and then measured in the packet exchange process)
    - Link Metric - a number from 0 -65,535, measured on the basis of LQ + RSSI + average Data Rate
    - Path Metric - the sum of Link Metrics to MPR.

    Configuring MeshConnex is quite simple in both CLI and GUI.

    Example statistics:

    Other important advantages of MeshConnex are:

    • High scalability (the number of points can be from 2 to 1000)
    • Low latency “per-hop” - 2.2 ms
    • Network may or may not have a wired “backhaul”
    • Mesh nodes can be mobile (all or some)
    • Mobile nodes can move at speeds up to 140 km / h (with “handoff” ~ 200 ms)
    • Fast convergence
    • Ability of the network to heal itself in case of accidents
    • Multicast support over mesh network

    If you need to build a wireless network with mesh elements for parking lots, industrial zones, open-space festival zones, mines, quarries, air and sea ports, we recommend using Mesh Connex for railway transport. Today, dozens of similar projects have been successfully implemented on the territory of Russia and neighboring countries.

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