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ADSL on 1721 - Can't Get it Working

Trying to configure my cisco 1721 w/ adsl wic to allow me to connect to the internet via ADSL. My provider has indicated that these are the correct settings:

VPI: 0 VCI: 38 Encapsulation: PPPoA using VC-Mux Authentication: CHAP Modulation: G.dmt

Have tried going through all the PPPoA docs on Cisco.com, but still can't get it working. I have gotten it so that the dialer0 indicates it gets the correct IP from my provider, but I can't ping any IP on the net (have not tried pinging from the dialer interface yet). Here is my config--any help greatly appreciated:

Using 1278 out of 29688 bytes ! version 12.3 service timestamps debug datetime msec service timestamps log datetime msec no service password-encryption ! hostname xxx

! boot-start-marker boot-end-marker ! enable secret xxx enable password xxx ! mmi polling-interval 60 no mmi auto-configure no mmi pvc mmi snmp-timeout 180 no aaa new-model ip subnet-zero no ip routing ! ! ! ! no ip cef ! ! ! ! interface ATM0 no ip address no ip route-cache no ip mroute-cache no atm ilmi-keepalive dsl operating-mode auto hold-queue 224 in pvc 0/38 encapsulation aal5mux ppp dialer dialer pool-member 1 ! ! interface FastEthernet0 ip address 192.168.20.1 255.255.255.0 ip nat inside ip virtual-reassembly no ip route-cache no ip mroute-cache speed auto ! interface Serial0 no ip address no ip route-cache shutdown no fair-queue ! interface Dialer0 ip address negotiated ip nat outside ip virtual-reassembly encapsulation ppp dialer pool 1 dialer-group 1 ppp authentication chap callin ppp chap hostname XXX ppp chap password 0 YYY ! ip classless ip route 0.0.0.0 0.0.0.0 Dialer0 no ip http server ! ! ! dialer-list 1 protocol ip permit ! ! control-plane ! ! line con 0 line aux 0 line vty 0 4 password login ! end

Reply to
jaybregman
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Hi Jay,

I can see that you have IP Routing disabled, enable it with: "ip routing"

The rest of the settings appear to be correct but let us know if that works.

I have a 1721 with ADSL-WIC and it works wonders..

Regards,

Rob

Reply to
RobO

Jay,

Another thing....

Do you have NAT setup at all, I see you have the NAT statements on the relevant interfaces but do you have a NAT pool setup or PAT(NAT overload) for that matter with an access-list?

Rob

Reply to
RobO

Do you not think it would be a good idea to try pinging from the dialer interface first? This seem to be a NAT problem rather than ADSL.

Reply to
Bob Goddard

Ok, Rob0 thanks for the ip routing spot--enabled it and I can now ping perfectly from the router (even without specifying the interface). However, when I try to use it with the setup I have, it doesn't work.

Here's the deal:

Router 192.168.20.1 plugged into switch--> external interface of W2003 Server (192.168.20.4)

That server Runs RRAS. It has nat enabled on the external interface and distributes DHCP addresses to clients, who have it's internal NIC

192.168.10.1 as their default gateway.

I am sure the problem is with NAT on the router, but I have 0 idea how to manage this on a Cisco...

Reply to
jbreg

Try adding:

access-list 1 permit 192.168.20.0 0.0.0.255 ip nat inside source list 1 interface Dialer0 overload

You may also want to enable CEF (ip cef) and fast-switching on the physical interfaces (ip route-cache), otherwise all your traffic is going to get process-switched, resulting in higher CPU usage.

Cheers,

Matt

Reply to
Matthew Melbourne

Jay,

Yeah just like Matt posted would be your setup for NAT but in effect you will be doing double NAT unnecessarily. You can disable NAT on the server and just add a route if it doesn't work.

Rob

Reply to
RobO

Matthew, you're a hero--it's working great now!

Jay

Reply to
jbreg

Matt,

So I can learn from this, what do these commands actually do?

access-list 1 permit 192.168.20.0 0.0.0.255 ip nat inside source list 1 interface Dialer0 overload

Reply to
jbreg

Effectively, they allow the source IP addresses 192.168.20.0/24 to be translated into the IP address assigned to the Dialer0 interface when the packets cross from an inside interface (FastEthernet0) to an outside interface (Dialer0). This form of NAT is really Port Address Translation (PAT), as all inside addresses are mapped onto a single outside address, and port numbers are used to differentiate the translations.

Use "show ip nat translations" to see how the router is managing the address translations.

Cheers,

Matt

Reply to
Matthew Melbourne

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