LAN and WAN Routing 2900 router

[bilal.su17]

we have a cisco 2900 router and which was configured by our previous ISP engineer, now we have changed our ISP the new ISP is proving us service through radio link they have set their device on tower from where a wire runs into an other device and from that device runs a line into cisco router wan port (the device is something like Poe they were calling) now they have given us an ip which we configured into when port but nothing is working before this with previous ip address given by former isp was working because all configuration was there so we thought every configuration is there we simply change the wan ip and it should work but it is not working although if  put that wire into a pc or a laptop it works the internet is working but on the router we are not able to ping even the gate way from router so my question is! is there any other configuration change also require

we have lan network that needs internet access. just tell me if any other configuration needs to be done other than changing the wan ip. as i said we did not change previous configuration we thought lets just put the wire change the wan port ip and we are good to go but its not working so  just tell me if any other configuration needs to be done other than changing the wan ip.

THANKS

[balaji.bandi]

can you provide the configuration and tell us what is other side IP address of the ISP ( please provide what IP information given by ISP to you).

[bilal.su17]

203.80.128.98 to 103 is the range of ip addresses we can use

we use this 203.80.128.98 on wan port
203.80.128.97 is the gateway gateway
255.255.255.248 subnet mask
sorry i can not provide full configuration info because i don't have much access i m just junior network administrator the senior one is on sick leave no contact with him 

on our lan port we have our lan network

100.120.50.1 gw and range 2 to 254

when we connect the same wire on a D-link router and put ip as well as gw everything works but do not know whats wrong with 2900 router cli configuration i will try and get the full configuration until than kindly tell me the possible causes what cmd could be missing why it is not picking the gw.

[balaji.bandi]

Since you have not provided the configuration look, i can only suggest high level

Step1 : you have configured WAN Port with IP address 203.80.128.98/29 with Gateway of 203.80.128.97

if the WAN Port up and you should be able to ping from router to Gateway IP 203.80.128.97  - Can you confirm this.

Step2 : if the above test working then, you need to configure NAT for your LAN IP address to get internet access.

LAN Interface. Example config for reference.

interface ether x/x 

ip nat inside

WAN Intercace 

interface gi x/x

ip nat outside

ip access-list 99 permit ip 100.120.50.0 0.0.0.255 any

!

ip nat inside source list 99 interface gi x/x overload

Test and advise form your LAN.