Site-to-Site VPN Routing: A Detailed Guide

John Doe

April 22, 2023

VPNs, or Virtual Private Networks, are very handy tools for maintaining your online privacy. VPNs can hide your IP address, protect you from malicious cyber attacks, and block annoying advertisements. When you browse the web with a VPN, it sends your data through its server before the website you want to browse receives it. In the process, your data gets encrypted so that your identity and location are kept hidden. This process of routing your data through a VPN server is known as VPN routing. 

Among different methods of VPN routing, site-to-site VPN routing is popular in particular. In this article, we are going to take a look at how site-to-site VPN routing works, its benefits, some drawbacks, and our overall feedback. 

What is Site-to-site VPN Routing

When two or more networks get connected to each other using the same OpenVPN tunnel, it is called a site-to-site VPN routing setup. Both networks can reach each other’s devices when site-to-site routing is active. It is fairly easy to implement site-to-site routing with the involvement of Access Server. 

Why Site-to-site VPN Routing is Necessary

In most cases, site-to-site VPN routing is necessary for organizations having more than one physical location. When an organization needs to maintain its operations across multiple locations, each location will have its own local area network. For secure cross-site communication, all these sites require a single corporate WAN. 

Site-to-site VPNs are perfect for this job. A site-to-site VPN creates an encrypted link between all the gateways placed at every site the organization has. Through site-to-site routing, the VPN encrypts the traffic at one end, and then sends traffic to the other sites through the public internet. Then the data gets decrypted and sent to the endpoint. This is a very convenient and secure way for such organizations to make sure unwanted third parties or hackers can’t breach their cross-site communication. 

Site-to-site VPN Benefits

Here are the major benefits you may receive from site-to-site VPNs: 

  • Due to advanced encryption methods, any data that passes through a site-to-site VPN is highly secured. Businesses have to exchange sensitive business data between their  locations. Site-to-site VPNs prevent the data from falling into the wrong hands. 
  • Business organizations maintain internal IP addresses for the devices used by their employees. If those internal IP addresses are to be accessed from a public network, they need to be converted to external IP addresses. Doing that may make the network exposed to data breaches or eavesdropping. With the help of site-to-site VPN routing, it is possible to exchange traffic from one LAN to another while keeping it internal. It is possible to ensure all sites use internal addresses and still use each others’ resources. 
  • Site-to-site VPN routing makes it easy for organizations to maintain access control. Complicated access control rules can be avoided by simply having a site-to-site VPN. as all the users of a site-to-site VPN network are considered internal users, traffic coming outside the network can’t simply be blocked. 

How a Site-to-site VPN Works

With a regular internet connection through a normal router, your data doesn’t have that many barriers surrounding it. While it seems fine, it might not be. Without the barriers, you are more likely to fall prey to malicious activities. Site-to-site VPNs create ‘tunnels’ between networks, specifically from one location to another. If you are logged into the network where the tunnel is, you’ll be able to see the transferred data. This way, any outsider is kept away from having access to the information. 

For this to work, VPNs make sure there are gateways at each location. The job of the gateways is to encrypt the traffic that goes through them. The gateways also send the encrypted data to the other end of the tunnel. When the other gateway receives the inbound traffic, it decrypts the data and sends it to the target host. This is one of the best methods to send and receive sensitive information. 

The encryption and decryption process is very important when it comes to protecting data from outsiders. Hackers and cybercriminals won’t be able to get hold of your information when the encryption is secure. They are not able to access the tunnel as well. 

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Site-to-site VPNs vs. Remote Access VPNs

Site-to-site VPNs create encrypted tunnels with IPsec. IPsec is a suite of protocols to create encrypted connections between multiple devices. This way a VPN tunnel is created to send and receive traffic between two servers. 

Remote access VPNs, on the other hand, form connections between individual endpoints and the office network using an SSL. It is an encryption based security protocol. With this process, remote access VPNs encrypt data for the traffic flowing over public internet between the office network and remote users. 

While both types of VPNs provide you with security, a site-to-site VPN does not provide a similar experience to being directly connected to your corporate LAN, unlike remote access VPNs. At times, this may hamper your browsing experience. 

Are Site-to-site VPNs Necessary Today? 

There was a time when site-to-site VPNs used to be very effective in protecting businesses from third-party cyber attacks. It acted as an efficient security mechanism for companies that need to connect their main corporate network to remote branch offices. Especially, companies with in-house data centers simply loved site-to-site VPN routing. However, site-to-site VPNs are becoming obsolete day-by-day. 

Unlike before, companies don’t prefer to have large in-house data centers. Most organizations keep their data and applications to the cloud. It makes sense for them because when you are dealing with an abundance of applications and data, having an in-house data center simply skyrockets the operation costs. Cloud servers are now more secure than ever before, and they are very cost effective. 

On top of that, making all the employees go through the in-house data center is really difficult if the workforce is big. For maintaining the in-house data center, companies must have a dedicated IT team. In addition, setting up network topology with access to the data center applications can be really tricky at times. 

For all these reasons, most companies today prefer cloud servers instead of in-house data centers. Hence, site-to-site VPN routing is no longer necessary for them. 

How Safe are Site-to-site VPNs?

To be honest, site-to-site VPNs are not your best option when it comes to security in today’s world. If you are using site-to-site VPN routing, the data is going to be encrypted between the two points only. However, you will not get any protection while the data is within the VPN tunnel. There is no content regulation or access control. Modern day hackers can steal information from the tunnel itself. 

If you want to keep your data secure with site-to-site VPNs, you’ll need to make sure that a spoke-hub process is in place to deal with the routing process. It must ensure that all the information passes through the company HQ, so that it can be monitored and inspected. For many reasons, this is a logistical nightmare. Your servers will have to deal with a massive load, resulting in your network getting slower. 

It is technically possible to secure your information well by using site-to-site VPN routing, but it’s not the most rational choice by any means. 

Site-to-site VPN Routing Limitations

Site-to-site VPN routing is a relatively old technology. It is understandable that this technology comes with its fair share of limitations. Here are some of the major limitations you’ll face with site-to-site VPNs: 

Difficult to Scale

It is not easy to scale site-to-site VPN routing. As this technology provides only point-to-point connectivity, you’ll need unique connections for every pair of sites that are going to be linked. If you have more than two locations that you need to connect via site-to-site VPN routing, you’ll need to increase the number of VPNs. It is not very practical for organizations that have a lot of connected locations. 

Limited Routing Efficiency

Despite the main objective of site-to-site VPNs is to secure the routing process, it has to be said that they don’t have the most efficient routing process. As there are not many built-in security features, many organizations have to resort to ‘hub and spoke’ network architecture. 

Such a network architecture helps a lot with reducing the number of required VPN tunnels, but it comes with another problem. As the main network must deal with security inspection, more often than not it suffers from network latency due to the additional workload. 

Visibility Fragmentation

Organizations find it really difficult to maintain total, integrated visibility into the network traffic it deals with. Every connection related to site-to-site VPN routing is independent. When a large-scale cyber attack happens, it becomes really tough to identify the connection that got breached. It results in delayed response time. When it comes to data breaches, delayed response time can cause severe damages to the company. 

Limited Integrated Security

There is no additional security feature in site-to-site VPN routing other than end-to-end encryption. There is nothing remotely close to content inspection or access control. Such a system is totally outdated in modern day computing. 

Difficult Management and Configuration

Due to each VPN tunnel being independent, site-to-site VPN routing is not easy to manage and configure at all. Every single VPN tunnel needs to be individually set-up, managed, and monitored. 

Lack of Flexibility

Once you opt into site-to-site VPN routing, opting out of it is not easy at all. As you must maintain an in-house data center for maximum security, you’ll have to completely change or update it once you decide to upgrade from site-to-site VPN routing. It requires a lot of money and resources. 

Best Alternative to Site-to-site VPN Routing

The best alternative to site-to-site VPN routing is SASE. The full form of SASE is Secure Access Service Edge. This is very convenient for organizations that use the cloud. SASE provides both networking and network security through cloud infrastructures. It eliminates the need for having an in-house data center. 

SASE comes with some additional security features that you won’t get if you use site-to-site VPN routing. For example, advanced threat prevention, web filter, DNS security, credential theft prevention, data loss prevention (DLP), etc. are some of the noteworthy security features offered by SASE. 

The best part about SASE is, it is very easy to implement and maintain. Connecting your remote offices together can be done without that much technical knowhow. 

Benefits of SASE

SASE has several benefits that you won’t get with site-to-site VPN routing. Here are some of the major benefits you’ll get to enjoy with SASE: 

  • Access to cloud data centers
  • Fast network speed
  • Quick and efficient identification of applications, users, and devices
  • Modern and strong security policies
  • Integrated security stack
  • SD-WAN functionality
  • Software-defined perimeter capabilities
  • Enforcement of least-privileged access
  • Simplification of the IT infrastructure
  • Affordable maintenance cost
  • Easy to use

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Bottom Line

Site-to-site VPN routing was a great security option for corporate connections. Over time, it could not keep up with other developed technologies. If we are to recommend VPNs to corporate organizations, we would definitely not suggest they try site-to-site VPNs. Remote access VPNs do a much better job, especially when most companies don’t maintain an in-house data center anymore. 

On top of that, with advanced technologies like SASE, there is no need to deal with the logistical hassle site-to-site VPN routing comes with. In fact, due to advanced security features, we would like to suggest companies with site-to-site VPN routing to upgrade to SASE. 

Frequently Asked Questions

What is the difference between static and dynamic site-to-site VPN routing?

Static routing is configured in advance of any type of network communication. For dynamic routing, it is necessary for routers to exchange information with each other before configuration. 

Do you need a static IP for a site-to-site VPN? 

Yes, you do. You can use site-to-site VPN routing without a static IP, but it’s far from the best practice. A dedicated static IP address is highly recommended if you are managing remote access for your workforce through a VPN.

John Doe



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