Anycast Metrics and Performance Tuning

Anycast has wide adoption in global network services such as Domain Name Service (DNS) and Content Delivery Networks (CDN). Its performance is determined by the location of client terminal, the anycast service points of presence (PoP), as well as network routing and conditions. The performance can be measured using various metrics such as latency and load balancing. The question arises what are the most useful metrics to evaluate anycast performance, and whether the operator can do anything to improve it. In this paper we define three performance metrics for anycast deployments, and propose several practical BGP configuration steps an operator can take to improve the metrics. Using these steps we show a significant improvement of anycast performance in our test deployment in Europe and the USA.