In IPsec, a symmetric encryption algorithm (e.g., AES) is used for encrypting data due to its speed. To securely exchange the symmetric key between peers, asymmetric encryption algorithms (like RSA) are used.

This method ensures:

High performance (due to fast symmetric encryption)

Secure key exchange (asymmetric protection)

Exact Extract - Huawei HCIE-Datacom Guide -- IPsec Encryption:

''IPsec uses symmetric algorithms to encrypt data for performance and asymmetric algorithms to securely exchange symmetric keys during IKE negotiation.''

Huawei HCIE-Datacom Study Guide -- IPsec Encryption Principles

Huawei IPsec VPN Deployment Guide -- IKE Phase 1 & 2