CCIE Security - VPN GRE-Based VPN

Generic Routing Encapsulation (GRE) tunnels provide a simple and flexible mechanism for encapsulating various network protocols within IP packets, enabling the creation of VPNs.

GRE tunnels establish a virtual point-to-point connection between two endpoints, regardless of the underlying network infrastructure. The original packets, including their headers, are encapsulated within a GRE header and a new IP header, allowing them to be transported over any IP network. This encapsulation allows for the tunneling of non-IP protocols, such as IPv6 or IPX, over an IPv4 network, or vice-versa.

GRE tunnels do not inherently provide encryption, so they are often combined with IPsec to add confidentiality, authentication, and integrity to the tunneled traffic. GRE's simplicity makes it easy to configure and troubleshoot, and its ability to carry diverse protocols makes it a versatile tool for network integration and VPN deployments.

However, the lack of built-in security necessitates careful consideration of security requirements and the potential need for additional security measures. GRE tunnels are commonly used for establishing site-to-site VPNs, connecting remote offices, or creating secure links over untrusted networks.

You might also be interested in these labs:

• CCIE Security - VPN GRE-Based VPN
• CCIE Security - VPN IKEv2 Lan-2-Lan or Site-2-site VPN
• CCIE Security - VPN GRE VPN over IPSEC
• CCIE Security - VPN GETVPN
• CCIE Security - VPN FLEX VPN L2TPv3
• CCIE Security - VPN DMVPN Dual Hub
• CCIE Security - VPN Certificate DMVPN
• CCIE Security - VPN Certificate Based Site-2-Sites VPN
• CCIE Security - VPN ASA Site2site through ASA and router IKEV and Anyconnect VPN with multiple profiles
  

The default username and password for images used in this course is as follows, however you will hear new passwords during the course if the instructor changes the credentials: 

** For Cisco XRv you are asked for a username and password in the loading process. You can add any username and password other than admin, root, sysadmin and other reserved usernames. Go with something like Alex/cisco e.g.

Then when completely loaded, you can use cisco/cisco or admin/admin.

***For XRv9K Full image you are asked for a username and password in the loading process. You then login using the username and password that you set.