upstream source {
   server 192.168.28.129:80 weight=1 max_fails=2 fail_timeout=30s;
   server 192.168.28.130:80 weight=1 max_fails=2 fail_timeout=30s;
}

server {
        listen       80;
        server_name  down1.example.com;
        location /source {
           root html;
           index index.html index.htm;
           proxy_pass http://source/;
           proxy_set_header Host $host;
           proxy_set_header Cookie $http_cookie;
           proxy_set_header X-Real-IP $remote_addr;
           proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
           proxy_set_header X-Forwarded-Proto $scheme;
           client_max_body_size 300m;
        }
}

192.168.28.129,192.168.28.130 為兩臺下載機的IP，現(xiàn)在下載地址直接是192.168.28.129，130 怎么操作能讓這個兩個IP變?yōu)橛蛎?/p>