3.5 Compare and contrast network access and management methods
📘CompTIA Network+ (N10-009)
A Site-to-Site VPN is a method of securely connecting two or more separate networks over the internet as if they were on the same local network. It is commonly used by businesses that have multiple offices in different locations.
Think of it as a secure digital bridge between two office networks.
Key Points for the Exam
1. Purpose
- Connects entire networks, not individual devices.
- Allows employees at different locations to access resources as if they are on the same network.
- Provides secure communication over the internet, protecting sensitive data.
2. How it Works
- Uses encryption (like a locked tunnel) to protect data traveling over the public internet.
- Typically uses devices called VPN gateways (often firewalls or routers) at each site to handle encryption and decryption.
- Traffic between the sites is transparent to the users. For them, it feels like all computers are on the same network.
3. Protocols Used
- IPSec (Internet Protocol Security): Most common for site-to-site VPNs. Provides encryption, authentication, and integrity of data.
- GRE (Generic Routing Encapsulation): Sometimes used in combination with IPSec to carry different types of traffic between sites.
- SSL VPN: Less common for site-to-site; usually used for remote access VPNs, but some businesses may use SSL for certain site-to-site connections.
4. Types of Site-to-Site VPN
- Intranet-based VPN: Connects networks within the same company.
- Example: Main office network connected to a branch office network.
- Extranet-based VPN: Connects networks between different companies.
- Example: A company network connected to a vendor or partner network securely.
5. Advantages
- Cost-effective: Uses the public internet instead of expensive private lines (like leased lines).
- Security: Encrypts data, so sensitive information stays protected.
- Always-on connection: Once configured, the VPN is active, so users don’t have to manually connect every time.
- Transparency: Users do not notice the difference; it’s seamless like a local network.
6. Disadvantages / Considerations
- Performance depends on internet connection: Slower connections can affect data transfer speed.
- Complex setup: Requires configuration of VPN gateways and sometimes routing adjustments.
- Single point of failure: If a VPN gateway or internet connection goes down, connectivity between sites is lost.
7. Real IT Environment Example
- A company with headquarters in New York and a branch office in London can use a site-to-site VPN.
- The VPN gateway at HQ encrypts traffic from its network and sends it over the internet to the VPN gateway in London.
- London decrypts the traffic, allowing employees to access shared files, printers, or internal apps securely, as if they were in the same office.
Exam Tips
- Remember: Site-to-site VPN = network-to-network, not device-to-device.
- Know the main protocols: IPSec and GRE.
- Understand the difference between intranet-based and extranet-based VPNs.
- Be aware of advantages (security, cost, always-on) and disadvantages (internet dependency, complexity).
✅ In short:
A Site-to-Site VPN securely connects entire networks across the internet, using encryption and VPN gateways, making multiple offices act as one seamless network.
