User profile for user: Mr. Z.
Mr. Z. Author
User level: Level 1
8 points

PPPoE over VLAN

I'm trying to set up a MacBook as a PPPoE client.
The provider requests me to send vlan tagged pppoe packets,
so I have set up a vlan interface (vlan0) for the ethernet
device (eth0) and added a pppoe interface to the vlan device.

I have connected the dsl modem to the macs eth0.

When clicking "connect" the ppp daemon starts, but after a while it gives up
without a connection. The log says, it cant find a pppoe server.

9/12/08 2:23:02 PM macbook pppd[1860] pppd 2.4.2 (Apple version 314) started by root, uid 501
9/12/08 2:23:02 PM macbook pppd[1860] PPPoE connecting to service '' [access concentrator '']...
9/12/08 2:24:07 PM macbook pppd[1860] PPPoE connection failed, No route to host

If I attach the modem to a vlan capable router, the connection comes up instantly.

Does anyone know if Mac OS X is really able to tagg pppoe packets? Linux and Vista do.

Any comment is very appreciated, thank you.

various (MacPro, MacBook, Mac Mini, Cube...), Mac OS X (10.5.4)

Posted on Sep 12, 2008 5:56 AM

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5 replies
User profile for user: Mr. Z.
Mr. Z. Author
User level: Level 1
8 points

Sep 18, 2008 6:34 AM in response to Mr. Z.

There seems to be a bug in Apples pppd or in PPPoE.ppp plugin.
When I try to setup the pppoe-connection this way:

pppd plugin PPPoE.ppp device vlan0 noauth defaultroute user username password pw

packets of ethertype PPPoE should go to vlan0. But tcpdumps didnt show any PPPoE packets
on that interface. Instead, all PPPoE communication is beeing sent to the standard ethernet interface en0.

Here is an excerpt of packet headers from the vlan0 dump:

tcpdump -nevv -XX -i vlan0 >tcpdump-vlan0.txt:

No ethertype of PPPoE in vlan, only DNS broadcasts...

14:53:55.485917 00:16:cb:cd:1f:df > ff:ff:ff:ff:ff:ff, ethertype IPv4 (0x0800), length 342: (tos 0x0, ttl 14:54:03.986736 00:16:cb:cd:1f:df > ff:ff:ff:ff:ff:ff, ethertype IPv4 (0x0800), length 342: (tos 0x0, ttl 14:54:12.933303 00:16:cb:cd:1f:df > ff:ff:ff:ff:ff:ff, ethertype IPv4 (0x0800), length 342: (tos 0x0, ttl 14:54:21.292128 00:16:cb:cd:1f:df > ff:ff:ff:ff:ff:ff, ethertype IPv4 (0x0800), length 342: (tos 0x0, ttl 14:55:30.249114 00:16:cb:cd:1f:df > ff:ff:ff:ff:ff:ff, ethertype IPv4 (0x0800), length 342: (tos 0x0, ttl

...

14:59:04.535913 00:16:cb:cd:1f:df > 33:33:00:00:00:fb, ethertype IPv6 (0x86dd), length 93: (hlim 14:59:04.635579 00:16:cb:cd:1f:df > 33:33:00:00:00:fb, ethertype IPv6 (0x86dd), length 131: (hlim 15:02:38.235331 00:16:cb:cd:1f:df > ff:ff:ff:ff:ff:ff, ethertype IPv4 (0x0800), length 342: (tos 0x0, ttl

...

15:04:20.721812 00:16:cb:cd:1f:df > ff:ff:ff:ff:ff:ff, ethertype IPv4 (0x0800), length 342: (tos 0x0, ttl 15:04:29.003659 00:16:cb:cd:1f:df > ff:ff:ff:ff:ff:ff, ethertype IPv4 (0x0800), length 342: (tos 0x0, ttl


--------------------------------------
tcpdump -nevv -XX -i en0 >tcpdump-en0.txt:

There is some vlan communication on en0, but these are only BootP/DHCP requests.
The PPPoE packets all seeme to go without vlan taggs...

15:08:44.894534 00:16:cb:cd:1f:df > ff:ff:ff:ff:ff:ff, ethertype 802.1Q (0x8100), length 346: vlan 7, p 0, ethertype IPv4, (tos 0x0, ttl 255, id 41394, offset 0, flags [none], proto UDP (17), length 328) 0.0.0.0.68 > 255.255.255.255.67: BOOTP/DHCP, Request from 00:16:cb:cd:1f:df, length 300, xid 0x7bc5028f, secs 24, Flags [none] (0x0000)
Client-Ethernet-Address 00:16:cb:cd:1f:df [|bootp]
0x0000: ffff ffff ffff 0016 cbcd 1fdf 8100 0007 ................
0x0010: 0800 4500 0148 a1b2 0000 ff11 18f3 0000 ..E..H..........
0x0020: 0000 ffff ffff 0044 0043 0134 6314 0101 .......D.C.4c...
0x0030: 0600 7bc5 028f 0018 0000 0000 0000 0000 ..{.............
0x0040: 0000 0000 0000 0000 0000 0016 cbcd 1fdf ................
0x0050: 0000 0000 0000 0000 0000 0000 0000 0000 ................
15:08:46.890680 00:16:cb:cd:1f:df > ff:ff:ff:ff:ff:ff, ethertype PPPoE D (0x8863), length 32: PPPoE PADI [Service-Name] [Host-Uniq 0x04348D04]
0x0000: ffff ffff ffff 0016 cbcd 1fdf 8863 1109 .............c..
0x0010: 0000 000c 0101 0000 0103 0004 0434 8d04 .............4..
15:08:49.891668 00:16:cb:cd:1f:df > ff:ff:ff:ff:ff:ff, ethertype PPPoE D (0x8863), length 32: PPPoE PADI [Service-Name] [Host-Uniq 0x04348D04]
0x0000: ffff ffff ffff 0016 cbcd 1fdf 8863 1109 .............c..
0x0010: 0000 000c 0101 0000 0103 0004 0434 8d04 .............4..
15:08:52.892753 00:16:cb:cd:1f:df > ff:ff:ff:ff:ff:ff, ethertype PPPoE D (0x8863), length 32: PPPoE PADI [Service-Name] [Host-Uniq 0x04348D04]
0x0000: ffff ffff ffff 0016 cbcd 1fdf 8863 1109 .............c..
0x0010: 0000 000c 0101 0000 0103 0004 0434 8d04 .............4..
15:08:53.209108 00:16:cb:cd:1f:df > ff:ff:ff:ff:ff:ff, ethertype 802.1Q (0x8100), length 346: vlan 7, p 0, ethertype IPv4, (tos 0x0, ttl 255, id 41395, offset 0, flags [none], proto UDP (17), length 328) 0.0.0.0.68 > 255.255.255.255.67: BOOTP/DHCP, Request from 00:16:cb:cd:1f:df, length 300, xid 0x7bc5028f, secs 33, Flags [none] (0x0000)
Client-Ethernet-Address 00:16:cb:cd:1f:df [|bootp]
0x0000: ffff ffff ffff 0016 cbcd 1fdf 8100 0007 ................
0x0010: 0800 4500 0148 a1b3 0000 ff11 18f2 0000 ..E..H..........
0x0020: 0000 ffff ffff 0044 0043 0134 630b 0101 .......D.C.4c...
0x0030: 0600 7bc5 028f 0021 0000 0000 0000 0000 ..{....!........
0x0040: 0000 0000 0000 0000 0000 0016 cbcd 1fdf ................
0x0050: 0000 0000 0000 0000 0000 0000 0000 0000 ................


Any comments would be appreciated, thank you very much (Apple, are you listening?)

Mr. Z.
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User profile for user: Tim Haigh
Tim Haigh
User level: Level 7
24,198 points

Sep 18, 2008 9:58 AM in response to Mr. Z.

This is not a direct solution but a suggestion.

I never come across your problem ever. The reason is I never use a computer a mac or pc as the PPPoE client, Why?

Because is not the most efficient way to maintain a broadband connection. The best way to do it is put router between the dsl modem and your computers.

better still get an ADSL router or DSL gateway. This is a box that is router with an integrated dsl modem.

The router has an embedded pppoe client and engages and maintains the connection independently from your mac. It also has other benefits such as a firewall, the ability to share your connection with multiple devices and is OS independant.
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User profile for user: Mr. Z.
Mr. Z. Author
User level: Level 1
8 points

Sep 18, 2008 10:29 AM in response to Tim Haigh

Tim,

thank you for your valuable reply.

There is a router at my dsl port, that all in all does its job.
But there is one backdraw: The dsl line delivers up to 50 MBit/s ⚠
The router cant cope with that (the router processor is too slow
for the job), its a bottleneck delivering not more than 35 MBit/s.

Using a Mac as a PPPoE client and the VDSL modem would circumvent the bottleneck.

BTW: Linux and windoze work just as expected, and do connect using tagged pppoe packets.
Leopard does not, tiger does not... 😟

Best regards,

Mr. Z.
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User profile for user: maba0902
maba0902
User level: Level 1
0 points

Oct 31, 2008 1:50 PM in response to Mr. Z.

Hi,

I´m experiencing exactly the same problem here, Leopard seems to be unable to send pppoe packets to pseudo-interfaces like vlans.
The only workaround i can think of is hooking up a vlan-capable switch between the mac and the vdsl modem. This way you should be able to tag the ppp packets correctly while maintaining the full bandwith. But then again, this means throwing additional money at this matter.
I guess otherwise we can only wait for OS updates

Regards,

Martin
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PPPoE over VLAN

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