So am I right in thinking that the following needs to be on both my new requests?

        self.session_id += 1
        req.addAVP(self.cx.getAVP('Session-Id').withOctetString("%s;%u;%u" % (settings.PUBLIC_HOSTNAME, self.session_id >> 32, self.session_id & 0xffffffff)))
        req.addAVP(self.cx.getAVP('Auth-Session-State').withInteger32(1))
        req.addAVP(self.cx.getAVP('Destination-Realm').withOctetString(self.peer.realm))
        req.addAVP(self.cx.getAVP('Destination-Host').withOctetString(self.peer.identity))