Comment by arghwhat
3 years ago
Nit: This is not a mesh. With only 3 nodes, it's not even a ring but just a direct connection between servers.
A "real" ring is formed when you have more than 3 nodes and so some destinations require more than one hop. A mesh implies a network formed by somewhat arbitrary point-to-point connections with multiple possible routes between two points.
Full-mesh typically means each node connects directly to each other node (for some value of directly), so IMHO, a three node system with each node connected to the other two fits the name. I do agree that it's not very interesting with only three nodes.
A network where every node has a direct connection is a point-to-point network. Yes, it is a special-case called a fully-connected mesh, but these networks are rarely made (a fully-connected mesh of 32 servers require 32 NICs in each server and 496 cables) and it is not a common term.
What is usually described as a mesh network (technically: "partially connected mesh") is a network where every node has a route to every other node, and that every node may have a direct connection to any number of nodes, but where there is no guarantee that any two nodes have a direct connection and may need to route over other nodes. The ability to handle this sort of completely arbitrary network topology is the core to mesh networks.
See https://en.wikipedia.org/wiki/Mesh_networking. There's also the old WiFi mesh spec (https://en.wikipedia.org/wiki/IEEE_802.11s, what the OLPC used), not to mention Zigbee and Bluetooth Mesh.
This may not be a ring, but a “real” ring doesn’t require more than 3 nodes. A ring can be formed with as little as 2 nodes.
If routing was enabled this would definitely be a mesh network. It would be a full mesh network where every node is directly connected to each other and a secondary path through another node is available should the direct path fail.
I was speaking from the perspective of a network, where you'd want to distinguish between a direct connection between two computers, and a network where you need to cooperate for routing.
This is not a ring because it is not configured as such: Rather, each network card has exactly one peer, and there is no knowledge of other peers, making it no different from just a direct connection between two computers.
If you had redundant paths, it would be a ring yes. A 3-node routable ring is in theory a special-case of a fully-connected mesh, but you do not call ring networks mesh networks. Mesh is usually reserved for when you truly mean to support arbitrary, disorganized network topologies
See https://en.wikipedia.org/wiki/Mesh_networking
A network where all nodes are fully connected to every other node and data can be routed through secondary indirect paths if the primary direct path fails is absolutely a mesh network.
And a 3 node ring is absolutely still a ring network.
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