nginx配置问题请教？

请教一个问题~
1.nginx做的反向代理。当访问http://www.123.com/abc，登陆成功后。同一个浏览器新开窗口输入http://www.123.com/abc，新旧窗口都不需要重新登陆，可正常访问
2.当新窗口输入http://www.123.com自动跳转http://www.123.com/123后，新网页需要重新登陆，原网页登出了，也需要重新登陆，这是为啥

nginx部分配置如下：

upstream localhost {
       server 10.20.2.1 weight=5 max_fails=1 fail_timeout=1s;
       server 10.20.2.2 weight=5 max_fails=1 fail_timeout=1s;
       server 10.20.2.3 weight=5 max_fails=1 fail_timeout=1s;
                   }

server {
        listen       80;
        server_name  www.123.com;
         charset UTF-8;

        location / {
            add_header Access-Control-Allow-Origin *;
            root   html;
            index  index.jsp index.html index.htm;
            proxy_redirect off;
            proxy_set_header Host $host;
            proxy_set_header X-Real-IP $remote_addr;
            proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
            client_max_body_size 10m;
            client_body_buffer_size 128k;
            proxy_buffers 32 4k;
            rewrite ^/(.*)$ /abc/$1 last;
            proxy_pass http://localhost;
            proxy_intercept_errors on;
            expires      1d;
        }

location /abc {
        proxy_pass    http://localhost;
        proxy_redirect default ;
        proxy_set_header Host $host;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header REMOTE-HOST $remote_addr;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
                 }
                 }