hello,today is very cool,keep me waking.yesterday i make a nat lab.enviroment is here,simple: pc-sw-r1(2511)-------(64kddn)----------r2(router at isp)----internet pc:10.10.10.1/24 r1:lan:10.10.10.2/24 wan:202.99.37.34/30 r2:wan:202.99.37.33/30 i want keep tracking the interface on r1 to r2 such as s0.i make a mirror between r1 wan and lan,and may i ping virtual lan interface to know exactly interface wan's state r1 configuration: lan:ip nat inside wan:ip nat outside wan nat is :ip nat source outside static 202.99.37.34 10.10.10.5 when interface wan in normal state i can ping 10.10.10.5 and 202.99.37.34 when i disconnect wan on r1,i can not ping 202.99.37.34 but can ping 10.10.10.5 i changed my r1 configuration: lan:ip nat outside wan:ip nat inside wan nat is :ip nat source inside static 202.99.37.34 10.10.10.5 now in normal i can ping either,when i disconnect interface wan ,i could not ping either,this is realy i needed. why the first configuration can ping 10.10.10.5 but second can't may i use first configuration to obtain my goal _________________________________ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]