ASR9k Split-horizon Summary
13 2 月, 2014,由 frank撰写
对于ASR9k的split-horizon简单总结如下：
注：ASR9k不同于76，split-horizon不能disable；它一共分3组，group 0，1和2，每组的定义不一样。
- 默认所有AC都属于group 0，group 0比较特殊，其中的AC都可以互访
- 所有PW都属于group 1，group 1中的member不能互访，但能与group0或group 2互访
- 不论在AC还是PW上配置split-horizion后，都会属于group 2，group2中的member不能互访，但能与group0或group1互访
下面是Xander总结的（https://supportforums.cisco.com/thread/2213114 ）：
Three SHG groups are defined for VPLS(SHG0,SHG1 and SHG2). By default, all the bridge-ports( AC or PW ) come in SHG0. When a Split horizon-group is configured under the Bridge-port( either under AC or PW) they come in SHG2. PWs defined under VFI come in SHG1. By definition, Bridge-ports in same SHG(SHG1 and SHG2) won't talk to each other ( this is not applicable for SHG0 though ). SHG0 --- > SHG0,SHG1 and SHG2 SHG1 --- > SHG0 and SHG2 SHG2 ----> SHG0 and SHG1