我按照文档https://istio.io/latest/docs/setup/install/multicluster/gateways/中的说明为istio设置了多集群复制控制平面，最后一步，我得到503错误
kubectl exec -n foo sleep-f8cbf5b76-fd9kk -c sleep -- curl -I httpbin.bar.global:8000/headers
HTTP/1.1 503 Service Unavailable
content-length: 91
content-type: text/plain
date: Mon, 10 Aug 2020 06:24:00 GMT
server: envoy