如何用wireshark抓取两个路由器之间的数据包

我主要是想用抓包工具，比如wireshark，来抓取两个路由器之间的数据报，学习OSPF路由协议的交互过程。

在网上查到可以用network tap（tap，test access port，测试接入点）或者dumb hub（dumb保证只收不发，不干扰监测线路）, capturing OSPF traffic in Wireshark between two routers。下图是抓取路由器和交换机之间的数据包的一个示例。

我在wireshark论坛中，找到了一个帖子，是介绍如何如何买到network tap的，描述如下：

***.***/questions/3413/network-tap

There are a number of vendors that sell those, and I have personally used TAPs from those vendors:

1.     Netoptics - ***.***

2.     Datacom - ***.***

3.     Finisar - ***.***, not sure if they still sell taps, doesn't look like they do

Then there are others, which I haven't tested myself:

1.     Gigamon - ***.***

2.     VSS - ***.***

and probably a couple more I haven't even heard of yet. I think most taps just work fine, I usually use the very basic full duplex taps from Netoptics and Datacom.   

经过网上搜索，找到了两款：

一是ebay上的finisar，***.***/itm/Finisar-UTP-Tap-IL-1-10-100-Network-Tap-New-In-Box-w-power-adapter/192667950714

二是datacomsystems的10/100-AT Network Tap，如下图所示

***.***/products/network-taps/10-100-at-network-tap

商品介绍如下：

The 10/100 Ethernet Tap is a single port device that provides a method to observe traffic on a full duplex Ethernet segment. The 10/100 Ethernet Tap provides easy access to segments while maintaining network integrity. Network performance will not be affected by power loss. 

附件是datacomsystems的network tap选型介绍，里面也有介绍什么地方用network tap。

但上面两个都是国外的，不太好买，所以，就想咨询一下国内有没有卖这种network tap的？在哪儿能买到？