<What>

Hot Standby Router Protocol (HSRP) is a Cisco proprietary First Hop Redundancy Protocol (FHRP) that provides high network availability by allowing multiple routers to work together to maintain access across the network. One router is active while others are on standby, ready to take over if the active router fails. Note that a virtual IP and a virtual MAC address are used for the FHRP.

Now with IPsec via GRE Tunneling, GRE has no encryption. With the help of IPsec, encryption is now possible and mitigates the risk of leaked or exfiltrated sensitive data from the tunnel. IPsec is used to set up VPNs because of the level of encryption and authentication.

<Why>

A quick overview for those who don't understand what encryption and hashes are don't worry I'll briefly explain their importance.

Encryption -> A method used to provide confidentiality between sender and recipient. Encryption works by converting plaintext into unreadable gibberish (ciphertext), ensuring that only the sender and recipient can access the data's content. Various encryption algorithms exist, with some being obsolete and others modern. Encryption protects the confidentiality of the data exchanged between both parties.

Hash -> A method used to ensure the integrity of data. Hashes generate a unique string of characters associated with the content of a file or data to ensure it has not been tampered with. Comparing the hash digest of the data to the original hash is crucial to verify that the data file remains unchanged. Think of it as a seal on a letter; if the letter seal is broken, it has been compromised. The same principle applies to hashes.

<Demonstration Video>

In this video, I’ll demonstrate how to use a high-availability protocol and configure a secure encrypted link over a tunnel. Implementing such configurations will not just ensure network redundancy, but also ensure data confidentiality.