Traditional data transmission channels will continue to function effectively for many years; however, they only become cost-effective in densely populated areas. In other situations, different solutions are needed to provide reliable high-speed connectivity at reasonable prices.
In this article, you will learn how to solve connectivity issues where traditional channels are expensive or unavailable. What classes of solutions exist, how they differ, and how to choose what you need for a specific task.
There are several classes of technologies claiming to address connectivity problems where traditional communication channels are absent or economically unfeasible. Balancers, aggregators, and summators seem to perform similar functions, yet they fundamentally differ in the quality of solutions they provide. Let's delve into the details.
Balancers
At any given time, only one channel is active. This addresses reliability through redundancy, but does not increase speed. Furthermore, the majority of balancers do not assess which channel is faster and simply switch to the one that is operational. 80% of market solutions that utilize multiple SIM cards are of this type, automatically switching connectivity to another channel when one loses signal.
There is a separate transitional class between balancers and aggregators. The speed for multiple streams, for example from several users simultaneously, will be higher than on any single one. When implemented correctly, this approach doesn’t require any traffic termination infrastructure and is widely used in the class of inexpensive routers. This solution can collectively provide high speeds, but each individual user will only receive speeds available on a single channel. Downloading torrents on such a device can be quite comfortable.
Problem Addressed
Increasing Reliability. Redundancy of data transmission channels.
Key Characteristic
- The speed at which the device switches from a non-working channel to a working one. The faster the device recognizes that one channel is down and needs to switch to another, the better.
- Priority operation on the fastest channel.
Advantages
- Device cost. The cheapest solution on the market.
- Does not require intermediate traffic termination infrastructure.
- Does not require skilled personnel for operation and maintenance.
Cons
- No quality check of the channel. The device may switch to a channel with poor connectivity while the adjacent channel is much faster.
Intended use
Services that do not require high data transfer speeds and are ready for short downtime.
Aggregators
This term comes from the English word 'aggregate'. In the context of data transmission systems, it has been used for a long time and applies to solutions that combine physical wired and optical data transmission channels.
These are more advanced systems compared to load balancers — they use multiple data transmission channels simultaneously. A connection is established through each channel with an intermediate server, where traffic is combined and further transmitted to the target service. Therefore, if even several channels drop, data transmission does not stop. There is no concept of switching from one channel to another. It should also be noted that, contrary to popular belief, most such solutions do not increase speed or do so insignificantly over wireless data transmission channels. For instance, 4 channels of 10 Mbps combined should give 40 Mbps, but aggregators in an L3 tunnel will provide around 12-18 Mbps. These are the maximum possible speed increases under ideal conditions. This is due to significant unequal entropy in the channels. It is a non-trivial task to combine channels with different throughput capacities and, most importantly, different latencies.
This is certainly better than ten, but significantly less than the expected forty. Unscrupulous manufacturers try to hide this deficiency by using a proxy server combined with a source address replacement. In this case, the speed increases drastically, but it only works when the connection is initiated from the device side. If the connection is initiated from the outside world, this trick will not work. If you want to connect two networks, for instance, a point of sale with the head office or a train with the central network – the aggregator will not manage the task, as the speed to the device will be ten times less than from the device. Moreover, in the case of using this in telecommunications networks, such manipulations will invariably raise questions from regulatory authorities regarding operational and investigative activities (OIA).
Solutions for aggregating wireless data transmission channels are relatively simple, requiring no investment in high-tech research. Almost all of them are based only on well-documented Open Source solutions. Manufacturers prefer to create a simple web interface and present it as an innovative development. This approach is very common in Russia.
Problem Addressed
Increased reliability. Slight increase in speed.
Key Characteristic
Utilization of aggregated channels. Average maximum data transmission speed.
Cons
- Device price. Substantially more expensive than ordinary load balancers.
- Presence of monthly payments since it requires intermediate traffic termination infrastructure.
- Specially trained technical staff is required for maintenance.
- Low utilization of data transmission channels in L3 tunnel.
- Proxy usageservers creates an asymmetric network and addressing.
Advantages
- Very effectively addresses the issue of data transmission channel redundancy.
- When using a proxy server, it provides high data transmission speed if the connection is initiated from the device.
Intended use
Services that require stable connectivity without the need for an L3 tunnel. Private households, simple topologies that do not require a symmetrical network. Not applicable for industrial facilities and telecommunications operator networks.
Aggregators
In the context of data transmission channels, this term has emerged in Russia only a few years ago. These solutions are very similar to aggregators, but they differ radically in that, while retaining all their advantages, they are devoid of all their shortcomings.
If end-to-end encryption from the device to the termination server is needed – this option, like on-the-fly compression, is available with mature technologies on the market.
For L3 tunnels, the utilization of data transmission channels by summators is around 90%. For instance, where an aggregator would provide 40 Mbps, a summator confidently delivers 70 Mbps. This is why it is referred to as a summator. This is a very complex task and requires serious scientific research.
Successful speed increases in an L3 tunnel provide a uniform network topology without 'peculiarities.'
Unlike aggregators, summators have no limitations on their areas of application. They can be used on any type of data transmission channels and any network topology. The network created by the summator is completely standard and, unlike aggregators, will not raise questions from regulatory bodies or hidden pitfalls in operation.
Problem Addressed
Increased reliability. Significant speed enhancement.
Key Characteristic
Utilization of aggregated channels. Average maximum data transmission speed.
Cons
- There are monthly payments, as it requires intermediate infrastructure for traffic termination.
- The price is comparable to that of an aggregator.
Advantages
- A highly efficient solution for channel redundancy.
- Significant increase in speed and bandwidth of channels in an L3 tunnel.
Intended use
Commercial, industrial, and government services requiring high speed and reliability of data transmission. There are no application restrictions.
Comprehensive solution
Technologies for increasing reliability and bandwidth, in addition to their primary function, should be easily manageable and scalable, providing comprehensive solutions to end-user problems without fragmenting the task and shifting a large part of the infrastructure and operational challenges onto the customer's competencies.
What is needed for a solution to be comprehensive?
1. Unified network management system
It allows management of all devices in the network—centrally updating firmware and configurations, generating alerts and notifications, and balancing network load. Transparently manage every function of each device individually and, in some cases, view the device's location and key features on an interactive map.
A quality network management system reduces engineering staff costs, decreases problem resolution time, and performs all the functions typically handled by the 'brain'.
2. Reliability
The technology involves using a traffic termination server that always stands between the device and the target service. It can become a single point of failure. If the solution does not automatically redistribute traffic from devices to termination servers and ensure automatic failover, it is not recommended for commercial use.
This is very important. Without an automatic backup system, even the fastest network will eventually turn into a network of 'bricks'.
3. Quality monitoring
The vast majority of solutions cannot log key performance metrics of devices when they are offline. That is, if there is a network problem, the system operator will not be able to conduct a retrospective analysis of the device and understand what exactly the issue was.
In critical infrastructure, devices must log the maximum number of metrics across communication channels for 'post-mortem analysis', be able to store them, and transmit to the central system without burdening the channels. No open-source monitoring system can simultaneously save bandwidth and deliver retrospective metrics.
4. Security
The network must be as secure as possible from malicious attacks on one side and be fully controlled by the client on the other.
5. Manufacturer support 24/7
It is very difficult to communicate with the manufacturer if they are in a different time zone and speak a different language or simply see themselves as royalty. It is very important that the manufacturer's response to a client's issue is minimal and that the solution genuinely resolves the problem.
What to choose
1. If you're satisfied with the operation of a single channel and just want to have a backup — choose a load balancer. It's simple, inexpensive, and efficient. It’s a bonus if the manufacturer has included the following modes:
-Concept of primary and backup channels. The backup channel activates only when the primary is unavailable. The primary channel turns on as soon as it becomes available.
-A mechanism for monitoring channel quality without generating overhead traffic.
-It’s a great advantage to increase overall speed by session-based traffic splitting among available channels. This will result in a significant cumulative speed boost, but will not increase speed within a single session.
These mechanisms work effectively only when used together.
2. If you need more speed than any single channel provides or require maximum speed — choose aggregators. Summs cost the same, but have fewer capabilities.
Source: habr.com
