Some encryption algorithms does not work in VPP
From the VPP/IPsec documentation
Supported cryptographic algorithms for encryption: aes-cbc-128 aes-cbc-192 aes-cbc-256 aes-ctr-128 aes-ctr-192 aes-ctr-256 aes-gcm-128 (128 bit ICV) aes-gcm-192 (128 bit ICV) aes-gcm-256 (128 bit ICV) des-cbc 3des-cbc
But with XFRM module it has more limitations
https://github.com/MarvellEmbeddedProcessors/vpp/blob/stable/2402/src/plugins/linux-cp/README#L145