Cisco 1801 - Switch from dynamic to static IP - Config change needed?

[FLVSteve]

Hello,

I have a remote client who is currently using a Cisco 1801 on a dynamic IP service. They need to change to a static IP, and I'm writing to ask if the router config will need to be changed once the service goes static?

The current (relevant part of the) config is this:

interface ATM0 description ADSL Connection to BTInternet no ip address no ip redirects no ip unreachables no ip proxy-arp ip route-cache flow no ip mroute-cache atm vc-per-vp 64 no atm ilmi-keepalive pvc 0/38  encapsulation aal5mux ppp dialer  dialer pool-member 1 ! dsl operating-mode auto

 and

interface Dialer1 description $FW_OUTSIDE$ ip ddns update hostname secrethost.dyndns.org ip ddns update DynDNS host members.dyndns.org ip address negotiated no ip redirects no ip unreachables no ip proxy-arp ip nat outside ip virtual-reassembly encapsulation ppp ip route-cache flow dialer pool 1 dialer-group 1 ppp authentication chap pap callin ppp chap hostname blahblah@btinternet.com ppp chap password 7 5A5A5A

 (I realise the dyndns stuff will be largely irrelevant, but it's easier than remembering numeric IPs!)

They are fairly distant from me, so visiting to do the changeover would be troublesome, and expensive for them. If the current config will work once they go dynamic that would be great.

If not, then I'll try reconfiguring remotely (into the startup config) and then they can reboot when the service changes, and with luck and a fair wind it'll come back up with the new config.

Any help very gratefully received.

Cheers.

Steve. 

[FLVSteve]

Don't know why the configs had all the line breaks removed from the code boxes. Here's what it should look like:

------------------------------------------------------

 interface ATM0

 description ADSL Connection to BTInternet
 no ip address
 no ip redirects
 no ip unreachables
 no ip proxy-arp
 ip route-cache flow
 no ip mroute-cache
 atm vc-per-vp 64
 no atm ilmi-keepalive
 pvc 0/38
  encapsulation aal5mux ppp dialer
  dialer pool-member 1
 !
 dsl operating-mode auto

 

---------------------------------------------

 interface Dialer1

 description $FW_OUTSIDE$
 ip ddns update hostname secrethost.dyndns.org
 ip ddns update DynDNS host members.dyndns.org
 ip address negotiated
 no ip redirects
 no ip unreachables
 no ip proxy-arp
 ip nat outside
 ip virtual-reassembly
 encapsulation ppp
 ip route-cache flow
 dialer pool 1
 dialer-group 1
 ppp authentication chap pap callin
 ppp chap hostname blahblah@btinternet.com
 ppp chap password 7 5A5A5A

----------------------------------------

Cheers. 

Steve 

[alastair · Accepted solution]

if its a single static ip ( which is what you'll want i think )  there will be no config required at all since the static ip is assigned by BT rather than config of the router.

you'll just need to reboot the router

[FLVSteve]

Hello,

Many thanks for that - I appreciate your help.

Regards.

Steve. 

[abieh]

Hi everyone,

after an outage with BT at the Kingston exchange this weekend my cisco 1801 did not want to sync the adsl. I spoke to BT and got the usual, "everything is fine our end, have you checked your password" response. I tested with an old router and found that to sync. (modem just makes the clicking noise - CD flashes and PPP is not lit)

I did a "sh dsl interface atm 0" and found that the modem status was DMTDSL_DO_DOWN and the DSL Mode was unknow. I found on some of the forums it was suspected to be an issue with auto negotiation of the ADSL Mode on the ATM interface.

So I started changing the ATM0 interface from "dsl operating-mode auto" to : 

- adsl2
- adsl2+
- ansi-dmt , and finally

- itu-dmt

Trying each for a a minute or so. (you can use "shut" and "no shut" to stop and start the ATM0 interface to speed up the process.)

Eventually it synced up with "dsl operating-mode itu-dmt" and all was fine again. I presume there was some equipment change which stopped supporting this feature.

Hope this helps someone

Abie

[Burkem5]

Hi Abieh, 

I have a few suggestions (bear in mind i am not cisco trained)

If you have an 800 series line card in your router you may need a set SNR margin of 9DB (ask for 12DB to ensure it wont drop below that) 

It could be that during the outage the DLM continued to adjust your profile and this results in the no sync issues you are seing.

If you can try that and let me know how you get on, I will try to dig up a bit more info for you in the mean time.

Hope this helps

Burkem5