第12题: [简答题]BGP的Community对于选择最优路径有什么作用? 参考答案:
BGP communitiy can be used to as tag of a set of routes. Those tags can be used for applying specific routing policy. Standard community does not affect best path selection of the local router.
The extended community , which is called cost community,influences the BGP best path selection process at the point of insertion(POI).By default,the POI follows the IGP metric comparison.Cost community is configured with a cost community ID and cost number.Path with the lowest cost community number will be prefered.If the cost community number is the same,path with the lowest cost community ID is prefered.