return status.Errorf(codes.ResourceExhausted, "request rate limit exceeded: %v", err)
	}

	ids, err := s.authenticate(ctx)
	if err != nil {
		return status.Error(codes.Unauthenticated, err.Error())
	}
	if ids != nil {
		deltaLog.Debugf("Authenticated XDS: %v with identity %v", peerAddr, ids)
	} else {
		deltaLog.Debugf("Unauthenticated XDS: %v", peerAddr)
	}