WIC-1-ADSL - Problems accessing the internet

[RKanathigoda]

Hello. I am working on a Cisco 2650XM with a WIC-1ADSL card and having difficulty getting my laptop or any other PC on the LAN to access (or ping) the internet. From my laptop I can ping the LAN and WAN ip addresses on the 2650XM. From the router I can ping and telnet remote hosts on the internet and my laptop. My ADSL line is fully functional as I am able to access the internet using a netgear router. Please help -Thank you ( I do not wish to use NAT as I am going to install a Firewall)

Here is my config

version 12.2
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname Test
!
!
ip subnet-zero
!
!
!
!
!
voice call carrier capacity active
!
mta receive maximum-recipients 0
!
!
!
!
interface ATM0/0
no ip address
no ip mroute-cache
no atm ilmi-keepalive
pvc 0/38
encapsulation aal5mux ppp dialer
dialer pool-member 1
!
dsl operating-mode auto
no fair-queue
hold-queue 224 in
!
interface FastEthernet0/0
ip address 192.168.254.254 255.255.255.0
no ip mroute-cache
duplex auto
speed auto
!
interface Dialer0
ip address negotiated
encapsulation ppp
dialer pool 1
dialer-group 1
ppp authentication pap callin
ppp chap hostname <username>
ppp chap password 0 <password>
!
ip classless
ip route 0.0.0.0 0.0.0.0 Dialer0
no ip http server
!
!
dialer-list 1 protocol ip permit
!
call rsvp-sync
!
!
mgcp profile default
!
dial-peer cor custom
!
!
!
!
line con 0
line aux 0
line vty 0 4
login
!
!
end

 

[pc2mike]

Greetings,
I noticed you have...

interface FastEthernet0/0
ip address 192.168.254.254 255.255.255.0
no ip mroute-cache
duplex auto
speed auto

... on your Ethernet interface. You can not route private IP addresses over the Internet. I suspect this is why your Linksys router works fine and the cisco 1720 does not. To learn more about RFC1819 goto

http://www.faqs.org/rfcs/rfc1918.html

Be Good,
pc2mike

 

[rainman]

Try un-numbering your Dialer0 interface (outside) to your fastethernet interface (inside). This will cause your LAN port to have a public IP address thus no NAT translation is necessary.


-Rainman

 

[l3stuff]

it's true that un-numbered will therefore assign your LAN interface to the Public WAN address, but that isn't your problem. Your devices (PC's) need to be in the same subnet as your LAN interface, in your case the 192.168.254.0/24 subnet.

When the packets from the PC's go out of the router, that is the source address they have in the IP header. Ok, this is (as mentioned) Private address space that everyone filters against. YOU NEED NAT to use this address space.

 

[RKanathigoda]

Dear All

Thank you for your responses. I have tried it with a public IP address and still does not work. I do not want to use NAT or IP Un-numbered as this configuration is going to be copied to a Cisco router, which has been configured to route IP from the LAN interface to the WAN interface. (Using 2 public IP addresses). The WAN Interface is connected to the ISP via X21 using HDLC. The ADSL will be used as a backup in the event of X21 line failure.

I think I have figured out the problem. With NAT or IP Un-numbered the public address is registered with the ISP. Any inbound traffic (like ping replies) knows the path back to the public address.

The problem is that the public IP address I was using is already registered with the ISP and traffic is directed to the X21 interface on the router and not the ADSL interface.
This is correct, as we do want traffic sent to the X21 interface first.

I am going to speak to the ISP to add a second route on their side so that if the X21 interface is down traffic will be routed to the ADSL interface.

Hope this works.