BACnet虚拟设备 - 永远不会响应直接命令(BACnet Virtual Devices - never respond to a direct command)

 一些背景：我正在尝试创建一个虚拟BACnet路由器，后面有虚拟设备（ 参见相关文章 ）。 我的测试环境由运行在我的服务器上的VM（10.2.0.15）组成，BACnet浏览器和Wireshark在其上运行。 我正在VS2013中编写代码，并在本地计算机上运行wireshark（192.168.56.1）。 
 
 当我启动虚拟路由器并从虚拟机发送who-is广播时，我看到在vm上运行的wireshark上的命令和响应。 在我的本地机器上，我只能看到wireshark中的命令，但没有响应。 
 
 所有这些工作正常。 但是，I-am响应的源地址（根据虚拟机上的wireshark以及BACnet资源管理器详细信息）是虚拟机和我的计算机之间的网关（10.2.0.2）的源地址。 
 
 问题后续的谁是针对特定虚拟设备的命令永远不会访问我的本地计算机。 我可以看到在vm上使用wireshark创建的命令，但是我的代码从未看到请求，我的本地计算机上的wireshark也看不到新数据包。 
 
 问题初始i-am响应的源地址应该是本地机器的IP地址还是我分配给虚拟设备的IP地址？ 如上所述，源地址当前是VM和我的机器之间的网关的地址。 
 
 以下是我用来构建对who-is命令的响应的NPDU部分的代码 - 希望有人能够指出我做错了什么。 
 
        bytes[pos++] = BACnetEnums.BACNET_PROTOCOL_VERSION;

        //Control byte determines what fields exist in the rest of the NPDU record
        bytes[pos++] = this.AssembleControl();  //in the case, the response is 0x28

        //Destination Network Info
        //65535 - Broadcast
        bytes[pos++] = 0xff;  //DNET
        bytes[pos++] = 0xff;  //DNET

        //Destination 
        bytes[pos++] = 0x00;  //DLEN
                              //DADDR
        //none since len = 0 and this is being broadcasted back

        bytes[pos++] = 0x00;  //SNET
        bytes[pos++] = 0x00;  //SNET

        bytes[pos++] = 0x06;  //SLEN

        //address should be 10.1.0.xxx, where x is the deviceid
        bytes[pos++] = this.SADR[0];  //10
        bytes[pos++] = this.SADR[1];  //1
        bytes[pos++] = this.SADR[2];  //0
        bytes[pos++] = this.SADR[3];  //varies based on the ID of the device - pulled from database
        bytes[pos++] = 0xBA;
        bytes[pos++] = 0xC0;

        //HopCount
        bytes[pos++] = 0xff;

Some background: I'm attempting to create a virtual BACnet router with virtual devices behind it (see related post). My test environment consists of a VM ( 10.2.0.15 ) running on my server with a BACnet explorer and Wireshark running on it. I'm writing the code in VS2013 and also running wireshark on my local machine ( 192.168.56.1 ).
 
When I start the virtual router and send a who-is broadcast from the VM, I see the command and responses on the wireshark running on the vm. On my local machine, I only see the command in wireshark, but not the responses going out.
 
All of this works fine. However, the source address of the i-am responses ( according to wireshark on the VM as well as in the BACnet explorer details ) is that of the gateway (10.2.0.2) between the VM and my machine.
 
The Problem Subsequent who-is commands targeting a specific virtual device never get to my local machine. I can see the command being created using wireshark on the vm, but my code never sees the request nor does wireshark on my local machine see a new packet. 
 
The Question Should the source address of the initial i-am responses be the IP of my local machine or the IP address that I've assigned to the virtual device? As stated above, the source address is currently that of the gateway between the VM and my machine.
 
Here is the code I'm using to construct the NPDU portion of the response to a who-is command - Hopefully someone can point out what I'm doing incorrectly.
 
        bytes[pos++] = BACnetEnums.BACNET_PROTOCOL_VERSION;

        //Control byte determines what fields exist in the rest of the NPDU record
        bytes[pos++] = this.AssembleControl();  //in the case, the response is 0x28

        //Destination Network Info
        //65535 - Broadcast
        bytes[pos++] = 0xff;  //DNET
        bytes[pos++] = 0xff;  //DNET

        //Destination 
        bytes[pos++] = 0x00;  //DLEN
                              //DADDR
        //none since len = 0 and this is being broadcasted back

        bytes[pos++] = 0x00;  //SNET
        bytes[pos++] = 0x00;  //SNET

        bytes[pos++] = 0x06;  //SLEN

        //address should be 10.1.0.xxx, where x is the deviceid
        bytes[pos++] = this.SADR[0];  //10
        bytes[pos++] = this.SADR[1];  //1
        bytes[pos++] = this.SADR[2];  //0
        bytes[pos++] = this.SADR[3];  //varies based on the ID of the device - pulled from database
        bytes[pos++] = 0xBA;
        bytes[pos++] = 0xC0;

        //HopCount
        bytes[pos++] = 0xff;

原文：https://stackoverflow.com/questions/34746404