PPPoE problems: Only the router is reachable

From: sthaug@nethelp.no
Date: Tue Jul 03 2001 - 20:02:03 EDT


I'm trying to debug ADSL/PPPoE here. The client is getting connected,
authenticated, and can ping the router. One would think that everything
is just great. But: If I try to ping anything other than the router
itself from the client, I don't get PPPoE packets back, instead I get
packets with ethertype 0x81f1.

Here's a ping from the client to the router itself (this works):

00:49:54.378180 0:60:8:62:23:af 0:50:b:b2:44:38 8864 106: PPPoE [ses 0x1] 195.204.234.1 > 194.19.1.211: icmp: echo request
00:49:54.387705 0:50:b:b2:44:38 0:60:8:62:23:af 8864 106: PPPoE [ses 0x1] 194.19.1.211 > 195.204.234.1: icmp: echo reply

Here's a ping from the client to a host reachable via the router:

00:50:00.657542 0:60:8:62:23:af 0:50:b:b2:44:38 8864 106: PPPoE [ses 0x1] 195.204.234.1 > 129.241.1.16: icmp: echo request
00:50:00.675143 0:0:3a:1:d2:60 45:0:0:54:7d:79 81f1 84:
                         0110 c3cc 0040 0000 2a6d 3801 0000 184c
                         423b 4e07 0a00 0809 0a0b 0c0d 0e0f 1011
                         1213 1415 1617 1819 1a1b 1c1d 1e1f 2021
                         2223 2425 2627 2829 2a2b 2c2d 2e2f 3031
                         3233 3435 3637

Notice I don't get a PPPoE packet back from the router. On the router, it
logs

Jul 4 01:53:32: Vi1 PPPOE: O FS

for each packet it sends of this strange type (this is with various
PPPoE debugging turned on, of course).

Anybody have an idea what is happening here? This is a 7204 running IOS
12.1(5)T8. Relevant parts of the config below. Oh yeah, the same router
works just fine using RBE instead of PPPoE.

Steinar Haug, Nethelp consulting, sthaug@nethelp.no
----------------------------------------------------------------------

vpdn-group 1
 accept-dialin
  protocol pppoe
  virtual-template 1

interface ATM2/0.2 point-to-point
 pvc 0/111
  vbr-nrt 1970 1970 100
  encapsulation aal5snap
  protocol pppoe

interface Virtual-Template1
 ip unnumbered FastEthernet0/0
 ip mtu 1492
 peer default ip address pool default
 ppp authentication pap



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