Troubleshooting guide

*Mar 3 03:33:19.539: Vi1 PPP: Phase is UP [0 sess, 0 load]
!−−− PAP negotiation was a success.
<... snipped ...>
Router#undebug all
Why can I access some web pages with PPPoE but not others?
Access to only some web pages is a common problem when running a PPPoE client on a router. By design,
PPPoE can support an MTU of up to 1492 bytes; therefore, you must ensure that end devices send out frames
no larger than 1492 bytes. Limiting the MTU to 1492 bytes could be a problem because most PCs and
end−user workstations have a default MTU of 1500 bytes.
There are two options for adjusting the MTU size: adjust the MTU size at the router and adjust the MTU size
at the PC.
Adjusting the PPPoE MTU Size on the Cisco DSL Router
Important Notes:
The following configuration commands work only if you are running Network Address Translation (NAT) or
Port Address Translation (PAT) on the Cisco DSL Router.
The ip adjust−mss command in Cisco IOS®Software Release 12.2(2)XH has changed to ip tcp adjust−mss
<mss value>. This change is documented in Release Notes for the Cisco 800 Series Routers and Cisco 820
Series Routers for Cisco IOS Release 12.2(2)XH.
!
vpdn enable
no vpdn logging
!
vpdn−group pppoe
request−dialin
protocol pppoe
!
interface ethernet0
no shut
ip address <ip address> <subnet mask>
ip adjust−mss 1452
!−−− The TCP MSS command requires an MSS of 1452, not 1492.
ip nat inside
no ip directed−broadcast
!
interface atm0
no shut
no ip address
no ip directed−broadcast
no atm ilmi−keepalive
bundle−enable
!
interface atm0.1 point−to−point
no ip directed−broadcast
pvc <vpi/vci>
pppoe−client dial−pool−number 1
!
!
interface dialer1
ip address negotiated
mtu 1492
ip nat outside
encapsulation ppp
Cisco DSL Router Configuration and Troubleshooting Guide