MS-MPPE keys in proxy

Hi, I am having trouble understanding the EAP-TLS authentication when requests are proxied. I want to know how MS-MPPE-Send-Key and MS-MPPE-Recv-Keys are transferred in proxy.. since these keys contain values calculated with EAP-Messages exchanged hashed with shared secret bla bla. Does the proxy keep its own EAP state and varialbe and calculates the Message Authenticator. or free-radius ignores these keys when exchanging EAP messages. regards