VPNs are evolving with every passing day. Invented back in the 90s to facilitate secure communication between the various business branches, they have seen a stable growth in technology and demand. Businesses choose to implement a VPN for two primary reasons: data security and secrecy. The recent spike in the uptrend of WFH (work from home) practices has made VPNs more crucial than ever for corporate stability. However, it isn’t easy to employ an integrated VPN network, especially on a large scale, which is where the VPN concentrator comes in.
VPN is a resource-hungry contraption that tests the computation prowess of a CPU, so a heavy workload can render the whole arrangement moot. It is why we saw the advent of VPN concentrators, hardware that shares the load of a CPU and lightens the network. Today we will attempt to learn more about this term. We will cover what a VPN concentrator is and how it works, amongst other topics.
An introduction to VPN concentrator
Often referred to as advanced routers, VPN concentrators create multiple VPN tunnels in a centralized manner to ease the load on a CPU. Therefore, they’re ideal for managing the flow of users and data encryption for an organization. VPNs are famous for creating tunnels to encrypt data. However, as the amount of data requiring encryption keeps rising, the CPU finds itself unable to manage the workload. The whole network also feels this stress. With so many tunnels and users to handle, especially in a large corporation, the administration frequently found itself in a pinch, which led to the usage of concentrators.
A VPN concentrator, like its name, concentrates the encrypted traffic within a network. To further elaborate, a VPN concentrator connects multiple networks and clients into a central network. I’m sure it sounds like a site-to-site implementation with a VPN gateway at the helm, but it is organically different. It categorically protects the communication between the remote branches and clients, like what you’d expect from the central network of the corporate.
A concentrator is a networking device that can be both physical and virtual. It works essentially as a router but for creating and managing inter-VPN communication. A VPN concentrator creates multiple tunnels at once to connect different VPN networks and joins them together. It is a server-side feature that aids the creation and management of numerous VPN connections remotely.
To sum up, a concentrator can simplify what a VPN achieves by utilizing multiple tunnels. It can do the same and much more by using a single tunnel to connect those multi-tunnel VPN nodes. By doing so, it eases the burden on the network and CPU.
How does a VPN concentrator work?
Imagine using a VPN to connect to the corporate network. Now imagine thousands of such individuals doing the same — it will create thousands of tunnels leading to the corporate network. Now, whether the network can handle the traffic or has enough computational power to work through it are not questions you need to ask. Regardless of how great a network is, in the face of thousands of simultaneous connections, it will lag. That’s why VPN concentrators are gaining popularity.
It is a device that has software loaded on it to work as an advanced router. It can create multiple tunnels at once and connect to those thousands of remote workers. In return, the concentrator connects to the network with a single tunnel. Thus, it combines multiple tunnels to manage off-site VPN networks and joins them into a central network that can access the corporate network as a singular entity. Here’s the process:
- A VPN user sends out a request to access the central network of a corporate.
- The traffic is encrypted.
- VPN concentrator will intercept this traffic before it reaches the network.
Remember that it intercepts thousands of such communication at once and processes them simultaneously.
- Now the VPN concentrator will decrypt each tunnel and combine them into a single one.
- This single tunnel will now communicate with the corporate network in real-time to avoid data loss.
- The concentrator will receive the result and initiate encryption.
- VPN concentrator now creates thousands of tunnels leading to the remote workers and forwards the results of their request.
The whole process takes place simultaneously, which is resource-intensive for a CPU. That is why VPN concentrators are often hardware-specific — they must produce such computational power.
What can VPN concentrators do?
A concentrator does what typically routers do but on a much larger scale. Concentrators are hardware-centric and rely on the heavy computational abilities to establish and configure communication tunnels, authenticate users, assign tunnel or IP addresses to users, encrypt and decrypt data, and ensure end-to-end data delivery. Additionally, they come with the ability to prevent and or defend against cyberattacks. But unlike routers, they are capable of managing thousands of tunnels at once. For convenience’s sake, you can define them as advanced routers.
The various functions of a VPN concentrator are:
- It forms multiple secure network tunnels.
- Authenticates remote users to access the central network servers.
- Encrypts and decrypts of traffic.
- It negotiates and defines the tunnel permutations and parameters.
- A concentrator ensures end-to-end encryption from a centralized network to a remote VPN node.
- It can manage the security keys associated with the network.
- It can optimize the data packets across the various tunnel connections already established.
- Handles the endpoints to affect inbound/outbound traffic.
Note — Do not confuse a VPN concentrator with a site-to-site VPN. True, a site-to-site VPN can also manage and connect remote VPN networks. However, the networks in question are always at a fixed location. A site-to-site VPN allows them access to a database and internal system. In contrast, a concentrator can connect multiple remote networks that are roaming or not fixed. Additionally, it joins them together to the central network and not a database.
Why use a Virtual Private Network concentrator?
VPN concentrators are not unique. They are also quite costly. So why use them, especially when you can allow secure communication from the remote client to the central server through cheaper options? What makes up for the high cost is the unique ability to create thousands of tunnels at once. Concentrators provide a high-performance output. Not only are they efficient and productive, but also expandable under the SEP (Scalable Encryption Processing) modules. Using SEP can increase the overall computing capacity of a concentrator and boosts its performance further.
They are capable of supporting thousands of users at once. Whether small-scale enterprises or a conglomerate, VPN concentrators have made lives easier for every business that relies on VPNs for connectivity. Here are a few convincing reasons:
- Supports users from around the globe by simply relying on the internet to access the corporate network
- It can enhance remote networks, even those that keep on moving from one place to other
- It can reshape and redirect traffic from thousands of tunnels at once
- A concentrator is a specialized type of router with more advanced protocols and algorithms
Now let’s elaborate on the three critical benefits of a VPN concentrator:
Secured private network
Some organizations require a high level of security for their operations. To avoid hijacking or cyberattacks from third parties or leaking data to unauthorized personnel, they decide to preserve them on technology that allows them to access private networks remotely. Sure, they can use either remote desktop or site-to-site VPNs for this, but remote desktops are easier to crack and site-to-site VPNs aren’t flexible enough. It makes the VPN concentrators the only choice. Concentrators use dynamic IP that makes it difficult for third parties to break private networks.
Unlimited network access
If a company needs to accommodate the entirety of its remote workforce simultaneously, there isn’t any other choice than a VPN concentrator. Although VPN routers work the same way, the scale is different. Concentrators can give access to thousands or even more employees, permitting concurrent connections to the network.
Both site-to-site VPNs or routers are suitable for either inflexible or limited access to a centralized network. However, a VPN concentrator doesn’t have this issue. It can take thousands of tunnels and connect them to a central network without loss of data. It can also help the administration manage these tunnels and shape the traffic itself.
Types of a concentrator
Since a concentrator relies on exceptional computational abilities to function, it is by and large based on dedicated hardware. The appliance itself is of a specified size that can accommodate numerous VPN connections according to the need of a network. However, most concentrators are often optimized for sizeable traffic alongside a dedicated focus on encryption and decryption capabilities to manage numerous tunnels simultaneously.
While it may be tedious and complex to configure large numbers of site-to-site IPsec VPNs, the use of dynamic multipoint VPN (DMVPN), a mechanism sponsored by Cisco, can simplify it quite a bit. That is why cloud deployment generally supports a simple software-only VPN concentrator that runs within the DMVPN or container environment.
There is also the option of utilizing open-source VPN concentrators. Some assembled open-source VPN concentrators include OpenVPN, pfSense, Linux implementation, and VyOS. Since they all support DMVPN, you can save costs on hardware concentrators and employ a software-only solution.
Encryption protocols it uses
VPN concentrators generally use IPsec (Internet Protocol Security) or SSL (Secure Socket Layer) security protocols. IPsec is the more popular of the two, as it provides users with the same level of access that they get if they connect locally. It is more secure than SSL, too. However, users need to configure client software on their devices to connect to the VPN network. SSL, on the other hand, is a web encryption protocol that is in-built within most browsers.
SSL is a universal application and its use doesn’t demand software configuration. You do not even need a fixed location when using this protocol to access a VPN — you can connect to the network with any device. However, it only gives remote users access to web-based applications. Although both of these two protocols are popular in site-to-site/remote access corporate VPNs, concentrators tend to opt for the IPsec protocol.
Notable features of IPsec:
- It is a common iteration that is popular amongst the corporate scene.
- This suite of protocols is exceptionally secure and effective at what it does.
- Needs proper client software to access the network. With authentication as a priority, corporates tend to employ IPsec indiscriminately.
- The protocol provides the best user experience for remote workers as if they were working locally.
- It can connect remote networks to a centralized one.
- It can provide local internal IP addresses to users with additional security.
- Requires technical skills to implement successfully.
- It can be tiresome.
- Limited to a fixed remote location.
Prominent features of SSL:
- Similar to IPsec, used primarily by corporate VPNs.
- Universal application that is inbuilt in most online browsers.
- Doesn’t require any specific software to connect to a VPN.
- It uses TCP port 443.
- It offers versatility.
- The corporate can also use Port forwarding to customize its configurations.
- SSL eliminates the need to configure every end-user device and client software manually.
- It doesn’t restrict the location of a remote worker. However, it works only with web applications.
Modes of transport
After the protocol, other things also need considerable pondering, such as what traffic a Wi-Fi will allow. Some are prone to blocking any IPsec traffic. Thus, there are a couple of methods to transport encrypted data.
- Transport mode — It wraps the encrypted data in a header and trailer. Then it allows the data to reach a remote site. It uses the original “header” to get the data across any blocks.
- Tunnel mode — It is even more advanced. This method will encrypt the header and footer but carries an additional IP header to the front of the data packets. The extra feature prevents anyone intercepting the data packets from knowing where it is going. In this mode, both the header and data are subject to encryption.
How does it impact performance?
No doubt, VPN concentrators are efficient. The hardware is designed to take the load off the CPU, making it exceedingly productive. It also eases the burden on the network by reducing issues like latency, data loss, or lagging. A concentrator can easily handle tens of thousands of users simultaneously, hence it’s preferable for solid performance and output.
Concentrators use SEP (Scalable Encryption Processing) modules to manage the encryption process without reducing performance. Also, with the module in place, the network can grow exponentially. As such, concentrators have long since become inevitable for both small and large-scale operations. They are the optimum solution for controlling and discerning data security.
Alternative to VPN concentrators
Throughout the article, we have mentioned technologies that are similar to a VPN concentrator. One can also utilize them if the conditions permit. Let’s take a closer look at these technologies as they are the optimum alternatives to a concentrator.
Although VPN routers are also capable of tunneling, it is pertinent to consider what kinds of applications will be using the network and what type of access will be needed. Routers may be less expensive but are rigid in their implementation and applicability. Also, they require configuring remote devices at an individual level. If the remote workforce is at a greater scope, the cost would easily outweigh the gain routers remit.
It is one of the most valuable methods to connect remote networks to a central one, especially if there are only two to three sites you must connect. Unfortunately, these locations have to be fixed. Thus, if you require remote access that is not limited by the number of networks or locale, use VPN concentrators.
Remote Desktop software
It can also create a secure connection between a user and the company. But the operationality of this method is very limited. Also, it isn’t equally safe as the other options. Luckily, an increasing number of such software uses an SSL-powered connection.