Mesh Calculations

Phil Morgan • October 12, 2017

Mesh Calculations

Thought I’d take some time to discuss bandwidth using Mesh APs and the associated mesh calculations.

This blog entry is aimed at a slightly advanced level, so I am working on the assumption that you already know how a Mesh works.

Basically, the node APs (MAPS or Node APs – do we call them “NAPs”?) are nodes that connect wirelessly back to a main node, sometimes called a Root AP or RAP. The nodes build a mesh that is self-building and self-repairing without any user intervention. If a node in the path to the RAP (this is the guy that connects the wired world, remember) fails, it just works its way around it, and rebuilds the path automatically.

All good so far but, with wireless, the available bandwidth on a network connection can be assumed to be 50% of the connection speed (simple math assumption for this exercise). This bandwidth is shared by everyone on the channel. You, your neighbors, and so on.

Well the problem here is that all the mesh APs are going to be on the same channel. They usually service one radio for clients (maybe two in certain circumstances) but then all connect one radio on a common channel for the path back to the RAP (this is called the “Backhaul”).

We can assume 4 Mesh APs share the bandwidth ¼ each, right? Well… maybe. If the Mesh APs are all one hop from the RAP, they will share the bandwidth 1/n (where n is the number of APs). See Diagram 1.

Mesh Calculations – Diagram 1.

Mesh calculations - A diagram of a switch , rap , map , and map.

What if we connect our APs differently? Take a peek at Diagram 2.

If 2 APs are one hop away from the RAP (called children of the RAP – that would make a great horror story, but I digress…), then they will share the bandwidth to the RAP. We know this calculates out to approximately 1/n each.

Then we connect the next 2 APs, each one hop away from the above mentioned children (technically, children of the children, so grandchildren of the RAP as it were). Now the math gets different. The data from these APs will first go across the wireless link up to the first hop (children), then continue over the wireless link a second time, up to the RAP.

So, data from a MAP (which is two hops away) crossed the network twice. Similarly, data from a MAP three hops away will cross the network three times.

Mesh Calculations – Diagram 2.

Mesh calculations - diagram of a switch , rap , map , and map.

This means that when you calculate the available bandwidth, you have to take into account the number of hops away the node is.

The calculation actually becomes a share of 1 / [(1xhop_1_aps) + (2xhop_2_aps) + (3xhop_3_aps)] and so on.

The configuration, from above, becomes 1 / [(1*2) + (2*2)], which means that having the 4 APs laid out so the 2 “grandchildren” APs link back to the two “children” APs will give each AP effectively 1/6 of the available bandwidth.

This is an oversimplification because, in a real mesh network, two distant MAPs may be far enough apart to not interfere which causes the numbers to improve slightly but, in general, it is a real-world phenomenon that causes rapid deterioration of bandwidth when you start deploying mesh networks with large depth (large number of hops away from the RAP). So you can summarize this discussion on Mesh, by saying “It’s not just the number of MAPs you have, it’s a function of the total the number and the number of hops they are away from the RAP”.

This is the bad news about mesh. Mesh is built for comfort and not for speed.

 

If you are looking to make your mark in the IT Industry, then NC-Expert offers excellent training courses aimed at relevant IT industry certifications –  contact us  today to get started.

NC-Expert Blog

By Rie Vainstein March 31, 2025
A Digital Shield for Your Online Adventures As tech professionals, we often spend a good chunk of our lives navigating the digital realm. Whether you’re troubleshooting a network, coding a new app, or just binge-watching the latest series, one thing is clear: your connection to the internet is a double-edged sword. It’s both incredibly convenient and, if not properly secured, a potential vulnerability. Enter the VPN (Virtual Private Network) our trusty, digital bodyguard. If you’re not already using one, or if you’re not entirely sure why you should, let’s walk through some of the reasons why a VPN is essential for anyone working in IT and, frankly, for anyone who uses the internet. What Is a VPN? In simple terms, a VPN creates a secure, encrypted tunnel between your device and the internet. It allows your data to travel securely, masking your IP address, and ensuring that no one (be it hackers or nosy advertisers) can track or intercept your online activity. Think of it as your personal “cloak of invisibility” in the digital world! 
By Phil Morgan March 13, 2025
Troubleshooting Wireless Networks with Ekahau: A Professional Engineer’s Guide Wireless networks have become the backbone of modern business infrastructure. From office environments to large-scale enterprises, ensuring a seamless wireless experience is essential for productivity. However, despite advancements in Wi-Fi technology, network performance issues often arise, ranging from signal interference and dead zones to capacity overloads and channel mismanagement. To tackle these issues efficiently, professional engineers rely on powerful tools. One such tool, Ekahau AI Pro, has become a gold standard in the wireless industry for troubleshooting and optimizing Wi-Fi networks. This blog delves into troubleshooting wireless networks using Ekahau tools, providing practical examples and technical insights to guide professional engineers in improving network performance.
By Rie Vainstein March 3, 2025
Futureproofing Our Security In our increasingly connected world, the security of digital information has never been more critical. From banking transactions to private communications, our data is constantly transmitted and stored across the internet. The current systems that protect this data rely on cryptography, a branch of mathematics that helps keep information secure by encoding it in ways that are difficult to decode without the proper key. However, with the rise of quantum computers, traditional cryptography is facing new and significant threats. This is where Post-Quantum Cryptography comes into play. What is Post-Quantum Cryptography? Post-Quantum Cryptography (PQC) [1] refers to cryptographic algorithms that are specifically designed to be secure against the power of quantum computers. Quantum computers, once they become practical, will be capable of solving complex mathematical problems much faster than classical computers. This will render many of the encryption methods we rely on today [such as RSA (Rivest, Shamir, and Adleman – initials of the inventors) and ECC (Elliptic Curve Cryptography)] vulnerable to attack. Quantum computers operate on quantum bits, or “qubits”, which can exist in multiple states simultaneously, unlike classical bits that are either a zer (0) or one (1). This allows quantum computers to perform certain calculations exponentially faster than classical computers. For example, in a matter of seconds, a quantum computer could potentially break an RSA key, which is considered secure by today’s standards. As quantum computing technology advances, the need for PQC becomes even more urgent.
Share by: