DSL negotiated IP addresses & NAT

This is very much on the same lines as the ISDN configuration except for the DSL PPP over ATM. Please note the ATM PVC vci/vpi, this is normally 0/38 in the UK. This is for BT and BT reseller customer. Your ISP should tell you this when your service is delivered. The other nice trick here is the dialer persistent, this causes the dialer interface to stay up all the time even if there is no traffic and to reconnect if the DSL connection is reset at any point.

Information Needed

From You
router                                              The hostname of your router
cisco                                               The password for telneting to your router
ciscoen                                            The password for enable access to your router

From your ISP
172.16.1.1, 172.16.1.2                   The DNS servers on your ISP’s network
0845XXX1234                               The Dial-up number for ISDN access to your ISP
user@yourisp                                  The username your ISP gave you
yourpassword                                  The password form logging into your ISP
ATM PVC 0/38                              This is normally 0/38 in the UK but some providers may be different

Sample Configuration

service timestamps debug uptime
service timestamps log uptime
service password-encryption
!
hostname router
!
enable secret ciscoen
!
ip subnet-zero
no ip source-route
ip dhcp excluded-address 192.168.0.0 192.168.0.10
!
ip dhcp pool home
network 192.168.0.0 255.255.255.0
default-router 192.168.0.1
dns-server 172.16.1.1 172.16.1.2
!
no ip bootp server
isdn switch-type basic-net3
!
interface Ethernet0
description === Your Local Network ===
ip address 192.168.0.1 255.255.255.0
ip nat inside
no cdp enable
!
interface ATM0
description === DSL Ling to ISP ===
no ip address
no atm ilmi-keepalive
pvc 0/38
encapsulation aal5mux ppp dialer
dialer pool-member 1
dsl operating-mode auto
hold-queue 224 in
!
interface Dialer1
ip address negotiated
encapsulation ppp
dialer pool 1
dialer idle-timeout 0
dialer persistent
dialer-group 1
no cdp enable
ppp authentication chap callin
ppp chap hostname user@yourisp
ppp chap password yourpassword
ppp timeout idle 2147483
ip nat inside source list 101 interface Dialer1 overload
ip classless
ip route 0.0.0.0 0.0.0.0 Dialer1
no ip http server
!
access-list 101 permit ip 192.168.0.0 0.0.0.255 any
dialer-list 1 protocol ip permit
no cdp run
!
line con 0
line aux 0
line vty 0 4
access-class 101 in
session-timeout 35791
password cisco
login
!
end

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