04-19-2020 05:33 PM
Hi all,
I'm looking for help resolving a routing issue when making a configuration change to a working router. Currently the router works well using an ADSL HWIC, with the LAN on fa0/1 and no connection to fa0/0.
To take advantage of a faster connection, I'm attempting to use an external bridged modem on fa0/0, with the intent to upgrade to VDSL service. Ideally, the C1841 will continue to perform NAT and hold the PPPoE credentials.
When using the external modem, the ATM interfaces are placed in shutdown, and fa0/0 is placed in service. I'm able to authenticate PPPoE as usual, but unable to route via browser either by DNS lookup or entered IP. I can ping from a PC, but NSLOOKUP fails multiple DNS servers and tracert dies at the 1841 router. I tried using an extended named ACL with no change.
NAME: "chassis", DESCR: "1841 chassis"
PID: CISCO1841 , VID: V05 , SN:
NAME: "WIC 1", DESCR: "ADSL over POTS"
PID: HWIC-1ADSL , VID: V01 , SN:
Router#sh flash
-#- --length-- -----date/time------ path
1 25645308 Jan 12 2019 01:57:10 c1841-broadband-mz.124-24.T3.bin
Current configuration : 2629 bytes
!
version 12.4
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname Router
!
boot-start-marker
boot-end-marker
!
logging message-counter syslog
enable secret 5 xxxxxxxxxxxxxxxxxxxx
!
no aaa new-model
clock timezone CST -6
ip source-route
!
!
!
!
ip cef
ip name-server 208.67.220.220
ip name-server 208.67.222.222
multilink bundle-name authenticated
vpdn enable
!
vpdn-group 1
request-dialin
protocol pppoe
!
!
!
vtp mode transparent
username xxxx secret 5 xxxxxxxxxxxxxxxxxx
archive
log config
hidekeys
!
!
!
!
!
interface FastEthernet0/0
description WAN
no ip address
no ip redirects
no ip unreachables
no ip proxy-arp
shutdown
duplex auto
speed auto
pppoe enable
pppoe-client dial-pool-number 1
no cdp enable
!
interface FastEthernet0/1
description LAN
no ip address
ip tcp adjust-mss 1452
duplex auto
speed auto
!
interface FastEthernet0/1.10
description Management
encapsulation dot1Q 10
ip address 10.1.10.1 255.255.255.0
!
interface FastEthernet0/1.20
description Wireless
encapsulation dot1Q 20
ip address 10.1.20.1 255.255.255.0
ip nat inside
no ip virtual-reassembly
ip tcp adjust-mss 1452
!
interface FastEthernet0/1.100
description 1st Floor
encapsulation dot1Q 100
ip address 10.1.100.1 255.255.255.0
ip nat inside
no ip virtual-reassembly
ip tcp adjust-mss 1452
!
interface FastEthernet0/1.200
description 2nd Floor
encapsulation dot1Q 200
ip address 10.1.200.1 255.255.255.0
ip nat inside
no ip virtual-reassembly
ip tcp adjust-mss 1452
!
interface ATM0/1/0
description ADSL WIC
no ip address
no atm ilmi-keepalive
bundle-enable
hold-queue 224 in
!
interface ATM0/1/0.1 point-to-point
description WIC ATM sub-interface
pvc 0/35
pppoe-client dial-pool-number 1
!
!
interface Dialer1
ip address negotiated
ip mtu 1492
ip nat outside
no ip virtual-reassembly
encapsulation ppp
ip tcp adjust-mss 1452
dialer pool 1
dialer-group 1
no cdp enable
ppp authentication pap callin
ppp pap sent-username xxxxxxx password 0 xxxxxxxxxx
ppp ipcp dns request accept
ppp ipcp route default
ppp ipcp address accept
!
ip forward-protocol nd
!
!
no ip http server
ip nat inside source list 1 interface Dialer1 overload
ip nat inside source static tcp 10.1.20.251 25565 interface Dialer1 25565
!
logging history size 30
access-list 1 deny 10.1.10.0 0.0.0.255
access-list 1 permit any
dialer-list 1 protocol ip permit
!
!
control-plane
Solved! Go to Solution.
04-21-2020 06:35 AM
Thanks for the replies!
The issue has been identified as a change in the ISP's processes.
Six months, or so, back, the ISP instituted a new process by which the PPPoE credentials are attached to the hardware address of the DSL modem in a back-end system. This prevents the user from swapping equipment at free-will: when the credentials are used with a 'new' modem, URL requests are redirected to a 'walled-garden' where the user can enter information about their account to permit the use of the new modem with the credentials.
The reason I was never redirected to the walled-garden page was the use of 3rd party DNS servers - if anything other than the ISP's DNS servers are used, the page hangs and eventually times out.
I was able to test and verify the problem by using a laptop with the bridged modem and setting up a PPPoE connection on the laptop.
It should be stated that my ISP discourages the use of 3rd party DNS servers, bridged-modems and non-ISP equipment - it would seem that these may have been a consideration when instituting this new process.
04-19-2020 08:31 PM
04-19-2020 09:33 PM
Try configuring fa0/0 in dialer 2 and check if that works.
04-21-2020 06:35 AM
Thanks for the replies!
The issue has been identified as a change in the ISP's processes.
Six months, or so, back, the ISP instituted a new process by which the PPPoE credentials are attached to the hardware address of the DSL modem in a back-end system. This prevents the user from swapping equipment at free-will: when the credentials are used with a 'new' modem, URL requests are redirected to a 'walled-garden' where the user can enter information about their account to permit the use of the new modem with the credentials.
The reason I was never redirected to the walled-garden page was the use of 3rd party DNS servers - if anything other than the ISP's DNS servers are used, the page hangs and eventually times out.
I was able to test and verify the problem by using a laptop with the bridged modem and setting up a PPPoE connection on the laptop.
It should be stated that my ISP discourages the use of 3rd party DNS servers, bridged-modems and non-ISP equipment - it would seem that these may have been a consideration when instituting this new process.
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