Example Cisco configuration for ADSL

Thought this may be of use to some. It's the key parts of the config I use on a 2600 with a WIC-1ADSL for my DSL connection. Posting because there seems to be a fair amount of confusion over how to configure these routers for use with DSL. That and the examples I often see online aren't very optimised.

Replace the angled bracket stuff with your own and this should be enough to get it connected and online.

Note this is using a Virtual-Template instead of a Dialer (as is in many online examples). A Virtual-Template will connect far faster due to the way they work in IOS. 'ppp lcp predictived' and 'ppp ipcp predictive' are both there also to speed up the connection process. With this lot retrains are in the order of 20-30 seconds normally vs. over a minute when using a Dialer withouth the predictive config lines.

'ppp ipcp route default' is a neat command that causes the default route to be dynamically added when it's received via IPCP. It saves you having to hard code the next hop or having a static default route pointing at the virtual-template. Sadly you need 12.3(11)T or newer for it to be there.

I've not shown other parts of my config that do things like QoS (inc. NBAR for protocol discovery), static DHCP mappings, general housekeeping stuff (controlling VTY access, configuring logging etc.) and NetFlow configuration (gives analysis on traffic flow patterns). If you're interested in that sort of stuff then let me know.

!

ip cef

!

ip dhcp excluded-address 10.0.0.200 10.0.0.254

!

ip dhcp pool <pool-name>

   network 10.0.0.0 255.255.255.0

   default-router 10.0.0.254 

   dns-server <DNS1> <DNS2>

!

!

interface ATM0/0

 no ip address

 no atm ilmi-keepalive

 dsl operating-mode auto 

 pvc 0/38 

  encapsulation aal5mux ppp Virtual-Template1

 !

!

interface FastEthernet0/0

 ip address 10.0.0.254 255.255.255.0

 ip nat inside

 duplex auto

 speed auto

!

!

interface Virtual-Template1

 ip address negotiated

 ip nat outside

 ppp lcp predictived

 ppp chap hostname <username>

 ppp chap password <password>

 ppp ipcp dns request

 ppp ipcp route default

 ppp ipcp predictive

!

ip nat inside source list 7 interface Virtual-Template1 overload

!

!

access-list 7 permit 10.0.0.0 0.0.0.255

!

Let me know if this is useful.

Cheers,
Chris.

Unfortunately I am on IOS 12.2(15)T but might try adapting this if I keep getting problems with the dialer interface.

Certainly having example working configurations will help people. Unfortunately each one, and the Cisco own examples seem to conflict. And Entanet who provide managed Cisco router so should be able to advise on configuration - refuse to do so.

It is also a shame that Cisco do not supply firmware updates unless you are on a paid support contract. A lot more smaller end and SME businesses might enter the Cisco world if they, and/or their consultants, could start of by experimenting with second hand kit. But Cisco's approach of treating their firmware as a commercial operating system that has to be purchased is an obstacle to market entry 8

They conflict because in IOS there is generally many ways to do the same thing. The config I posted is what I consider to be a fairly optimised one for performance and simplicity, but it means a fairly new IOS. It can easily be chopped about to suit older IOS.

'ip address negotiated' can be replaced with a hard coded IP.
'ppp ipcp route default' can be replaced by a static route 'ip route 0.0.0.0 0.0.0.0 <int>'
'ppp lcp predictive' and 'ppp ipcp predictive' are both there just for improvements in connection setup time.

AFAIK you can buy IOS versions, you don't need a service contract. And yeah, they do treat it as a commercial operation system because it sort of is. It's not firmware. That same IOS is fairly similar from low end customer routers to the high end core stuff. I guess from Cisco's point of view, you will buy one of their Linksys products if you want general run of the mill kit. If you want something that can be customised to do almost anything then IOS is the thing.

You can get a Smart Net contract for not alot of cash.

Cisco 1801, IOS 12.4.11

interface ATM0
no ip address
no ip redirects
no ip unreachables
no ip proxy-arp
ip route-cache flow
no atm ilmi-keepalive
dsl operating-mode auto
!
interface ATM0.1 point-to-point
description WAN
no snmp trap link-status
pvc 0/38
encapsulation aal5mux ppp dialer
dialer pool-member 1
!
!
i
interface Dialer0
description Dialer_Interface
ip address negotiated
ip access-group 111 in
no ip redirects
no ip unreachables
no ip proxy-arp
ip nat outside
ip inspect DEFAULT100 out
ip virtual-reassembly
encapsulation ppp
ip route-cache flow
dialer pool 1
dialer-group 1
no cdp enable
ppp chap hostname 1234@zen
ppp chap password xxxxxxxxxxxxxxxxxxxxxxxx

Cisco 837, IOS 12.3.11

interface ATM0
no ip address
no ip mroute-cache
atm vc-per-vp 64
no atm ilmi-keepalive
dsl operating-mode auto
pvc 0/38
oam-pvc 0
encapsulation aal5mux ppp dialer
dialer pool-member 1
!
!
!
interface Dialer0
no ip address
!
interface Dialer1
ip address negotiated
ip access-group 111 in
ip nat outside
ip inspect myfw out
ip virtual-reassembly
encapsulation ppp
dialer pool 1
dialer-group 1
ppp chap hostname 1234@zen
ppp chap password xxxxxxxxxxxxxxxxxx
ppp ipcp dns request
ppp ipcp wins request
hold-queue 224 in

Neither the most optimum of connection configs but as said "there is more than one way to skin a cat" with Cisco.

Edited by Rockh (Thu 26-Apr-07 19:31:25)