春节期间找到一篇文章，需要 fg 才能看到：

https://medium.com/@tumalevich/kamailio-registration-replication-without-dmq-65e225f9a8a7

kamailio1 192.168.56.115
kamailio2 192.168.56.116
kamailio3 192.168.56.117 

route[HANDLE_REPLICATION] {
  if(route(FROM_REPLICATION_PEER)) {
    if(is_method("REGISTER")) {
      add_rcv_param();
      msg_apply_changes();
      if(!save("location", "0x02")) {
        xlog("L_ERROR", "Replication from $si error");
      }
      exit;
    }
    if(is_method("INVITE")) {
      record_route();
      route(LOCATION);
    }
  }
}
route[FROM_REPLICATION_PEER] {
  if(src_ip == myself) {
    exit;
  }
  if(($si == '192.168.56.115') || ($si == '192.168.56.116') || ($si == '192.168.56.117')) {
    return 1;
  }
  return -1;
}
route[REPLICATE] {
  forward('192.168.56.115', 5060);
  forward('192.168.56.116', 5060);
  forward('192.168.56.117', 5060);
}

修改处理 REGISTER 的路由块：

route[REGISTRAR] {
	if (!is_method("REGISTER")) return;

	if(isflagset(FLT_NATS)) {
		setbflag(FLB_NATB);
		# do SIP NAT pinging
		setbflag(FLB_NATSIPPING);
	}
	if (!save("location")) {
		sl_reply_error();
	}

	route(REPLICATE); // 新增
	exit;
}

修改 request_route 路由块：

request_route {

	# per request initial checks
	route(REQINIT);

	# NAT detection
	route(NATDETECT);

	# CANCEL processing
	if (is_method("CANCEL")) {
		if (t_check_trans()) {
			route(RELAY);
		}
		exit;
	}

	# handle retransmissions
	if (!is_method("ACK")) {
		if(t_precheck_trans()) {
			t_check_trans();
			exit;
		}
		t_check_trans();
	}

	# handle requests within SIP dialogs
	route(WITHINDLG);

	### only initial requests (no To tag)

	route(HANDLE_REPLICATION); // 新增

	# authentication
	route(AUTH);

	...