In order to generate multiple session keys from a Diffie Hellman key agreement protocol, I'm trying to use the HKDF to generate this session keys. The HKDF algorithm uses an Extraction-Expand procedure. In the extraction procedure, it takes as an input a salt and a source key (in my case it will be the Diffie Hellman generated key). I know that the salt it is a random non-secret value.
My question is: How do I establish this random salt value between two entities? Can I set this value by applying a hash function to my Diffie Hellman key like
Salt = HashFunction(DiffieHellmanKey)?