There are many questions regarding Firetide’s mesh technology, and this posts attempts to address some of them. As you will see from the post, Firetide’s mesh is neither Layer 2 nor Layer 3, but a hybrid, unique to the industry.
Layer 2 / Layer 3 Hybrid Approach
Layer 2 vs Layer 3 benefits and trade-offs have been a topic of discussion for a couple of decades as both approaches have their benefits and drawbacks. Firetide offers a L2/L3 hybrid approach, which leverages the positives from both technologies and does away with the shortcomings, such as Layer 2′s lack of scalability and Layer 3′s latency and chattiness.
Firetide’s technology looks as a Layer 2 switch to outside world. Internally Firetide uses a Layer 3 approach to deliver the packets from an injection point of the mesh to an exit point. In doing so the packets can be load-balanced and re-routed based on advanced metrics maintained within the mesh. The hybrid approach makes the wireless network more scalable as well as enhances its performance.
Distributed Wireless Ethernet Switch
Firetide infrastructure mesh is built out of Firetide mesh nodes, which, combined into a network topology (mesh, point-to-point, point-to-multipoint, or a combination), form a “distributed wireless Ethernet switch.” The mesh nodes (in our terminology) are neither access points nor routers. Hence we call them nodes.
The term “distributed wireless Ethernet switch” means that the features provided are equivalent to a traditional wired Ethernet switch. In a wired Ethernet switch, Ethernet interfaces are provided via line cards on a chassis based model. The central switching is done via a central card that switches Ethernet packets from one line card port to another line card port. Firetide follows a similar approach. The line card equivalent of Firetide’s product offering is the mesh node, while the central switch is the radio medium itself. The nodes may be a mile to several miles apart.
The simplicity of Ethernet switch is illustrated the point that a 100-port Ethernet switch needs one single management IP address. In the same way, a 100-port Firetide mesh (formed with 25 indoor mesh nodes, for example) will have a single management IP address. The distributed Ethernet switch architecture is patented technology of Firetide and provides:
- Seamless transport of IPV4 and IPV6 packets
- Load balancing across the entire mesh
- End-to-end encapsulation (on top of encryption) for added security, reliable handling of multicast traffic, and no introduced jitter
- Simple installation and expansion of a mesh network. With a ‘routed mesh,’ this would require a complex configuration whereas each node has unique user-described IP address etc.
Firetide is the only provider with a distributed Ethernet switch-based infrastructure mesh. Most other wireless mesh in the market is a simple extension of access point-based technology, although some Layer 3 mesh also exists.
Flow-based Routing
The stitching of Layer 2 and Layer 3 is done on a flow-based model. The flows are Ethernet flows that are maintained within the mesh domain. The flows are then wirelessly switched across the distributed radio infrastructure.
Firetide built a protocol from the ground up with wireless in mind. Our flow-based routing algorithm creates a unique tunnel by encapsulating each packet with a flow instruction header specific to each stream; the header defines the least cost route for that specific packet from its source to its destination. Since flow instruction headers are used to determine the destination, the packets do not undergo deep packet inspection at each hop. In this way, we avoid extra overhead created by the millions of pings involved in resetting routing tables. Reduced overhead means more throughput for the user traffic.
These flows also help maintain unique, synchronous streams end-to-end. By maintaining the packets in these non-interleaved tunnels, the mesh makes sure that the packets arrive at the destination on time, in order, and with no introduced jitter (variation of latency).
Firetide mesh networks use load balancing across multiple paths for maximum network capacity. The mesh nodes manage the traffic across the network and can intelligently decide along which of 3 predefined flows a packet should be sent.
Performance
Firetide offers industry’s only wireless mesh that provides 100-150 Mbps of UDP payload sustained over multiple hops in outdoor deployments (real throughput, not theoretical data rate). When deployed in point-to-point mode, through radio bonding, we can provide real-world throughput of 200-300 Mbps outdoors.
What Firetide Mesh is Not
Even though Firetide mesh looks to the outside world as a Layer 2 switch, it does not perform “Layer 2 switching,” nor is it based on bridging two Wi-Fi radios together in WDS mode. On the switching side, Firetide mesh uses cut-through forwarding, as opposed to store-and-forward methodology. (Here’s a good definition from Cisco: “Whereas a store-and-forward switch makes a forwarding decision on a data packet after it has received the whole frame and checked its integrity, a cut-through switch engages in the forwarding process soon after it has examined the destination MAC (DMAC) address of an incoming frame.” See more on the two approaches: Cut-Through and Store-and-Forward Ethernet Switching for Low-Latency Environments.) In other words, Firetide mesh protocol performs proper routing across multiple hops, with cut-through forwarding approach allowing for industry’s lowest latency in wireless mesh: sub 1 ms per hop.
More questions? Please let me know in comments or via Twitter.
For more discussion on mesh technology, see
- How Long Does Mesh Go?
- When Wireless Video Mesh is Not ‘True’ Mesh (But Better)
- Network Design Considerations for Wireless Video Surveillance
- Technology Behind Wireless Infrastructure Mobility
- Questions and Answers on Firetide Wireless Mesh: From Obscure to Common
By Ksenia Coffman – Connect with me on Twitter or LinkedIn.
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