Issue with RB5009 ROS v7.1rc1 DHCPv6-PD over pppoe on tagged ethernet link

RouterOS RouterOS beta
1

Hi,
my setup is as follows:
ISP fiberlink (media converter) <(1G Copper SFP)> CRS317 <(SFP+ AOC)> RB5009 (was RB4011)

The ISP expects pppoe on VL1002, so I configured the CRS317 to have VL1002 tagged on both links, towards ISP and the Router). Now the strange issue:
IPv4 does work through the pppoe session without any problems. But to get IPv6 connectivity I need to issue a DHCPv6-PD request. This does work reliably with the RB4011. Now I replaced the RB4011 with an RB5009, same OS version, basically same config.
With the RB5009, which I connected to the same AOC through the SFP+ interface it doesn’t. I did some sniffing and mirroring on the RB and the CRS. What I see is that the RB5009 issues the request and I do see the answer at the CRS as expected. Sniffing on the RB5009 I do not see that answer anymore.

As last attempt I removed the tagging of VL1002 between the RB5009 and the CRS. Now it started working and has been stable ever since.

Smells like a bug to me …

Update:
Also on 7.1rc2

2

Similar issue.
RB5009 running 7.0.5
PPPoE client on VLAN 10 on ether1
DHCP Client for DHCP-PD just stuck on searching…

Replace RB5009 with CCR running 6.48, same config, works fine.

EDIT: Just upgraded to 7.1rc4 and same issue

3

Known issue, they are working on it. Meanwhile you can use untagged and tag the VLAN on an external switch.

4

Thank you :slight_smile:

5

Supposedly fixed in v7.1rc5 but doesn’t seem to work for me… any luck?

*) pppoe - fixed DHCPv6 PD;

6

I can confirm that this issue is not fixed on rc5.

but there is a workaround, if you put the vlan interface for the pppoe on a bridge, DHCPv6-PD works

7

Could confirm that in 7.1rc6 issue is not fixed. DHCPv6-PD works on untagged interface, but not on tagged.
P.S. KPN uses PPPoE on vlan 6 for internet connectivity

8

This cannot be done as the pppoe client need to be attached to the vlan. If the vlan is put under a bridge, how can the pppoe client connect to its pppoe server?

9

Create (another) bridge, add physical interface to it as tagged bridge port, set bridge interface as tagged member of same VLAN, create corresponding VLAN interface and set pppoe client to use this VLAN interface. Or set bridge interface with PVID set to VLAN ID, set bridge interface as untagged member port of said VLAN and set pppoe client to use bridge interface (as it’s untagged already).

Make sure you explicitly disable HW offloading for this bridge … there’s nothing to offload in this case since all traffic will have to pass (slow) CPU anyway.

10

Hello you can do like the example below:
note that in my case I use two PPPoE connections, one for v4 another for v6

/interface bridge
add name=bridge priority=0x4000
/interface vlan
add interface=bridge mtu=1600 name=WAN_vlan vlan-id=35
/interface pppoe-client
add add-default-route=yes disabled=no interface=WAN_vlan name=PPPoEv4 user=<redacted>
add disabled=no interface=WAN_vlan name=PPPoEv6 user=<redacted>/ipv6
# in case that you have bridge vlan filtering on
/interface bridge vlan
add bridge=bridge comment=WAN_vlan tagged=ether10,bridge vlan-ids=35
11

I tried your setup but it didn’t work. How come you only put a vlan under a bridge interface without any ether interface for the bridge? The bridge itself not physical interface, I am so confuse now.

12

I came up with similar solution. And it works.
The only catch was l2mtu on ports/bridge due to KPN using jumbo pppoe mtu and mru.

13

Question, is this only a problem when pppoe is involved or every time when DHCPv6-PD goes over a VLAN-tagged interface?

I have to set on the WAN Interface VLAN 7, IPv4 DHCP-Client get the IP. Starting the v6 DHCP client, it search forever. I currently investigating, if it’s a problem on my side, or on the ISP.

14

Have same issue. I confirmed that v7.1rc7 still not fixed this issue

15

Dear joedoelv do you mind sharing your setup for KPN or any hint for fixing MTU? It has been 3 days pulling my hair out to setup dhcp-pd for KPN with no luck..

Here is a snap of my latest config:

/interface bridge
add name=br_wan

/interface bridge port
add bridge=br_wan hw=no interface=ether8

/interface vlan
add interface=br_wan name=vlan_wan vlan-id=6

/ppp profile
set *0 use-ipv6=no
add name=ipv6 use-ipv6=required

/interface pppoe-client
add add-default-route=yes allow=pap disabled=no interface=vlan_wan name=ppoe_wan
add allow=pap disabled=no interface=vlan_wan name=ppoe_wan6 profile=ipv6

/ipv6 dhcp-client
add interface=ppoe_wan6 pool-name=kpn request=prefix

MTU

Interface | MTU  | L2 MTU
br_wan    | 1500 | 1514
vlan_wan  | 1500 | 1510
ppoe_wan6 | 1480 | -
16

I have the same issue, v7.1 (stable) still hasn’t resolved the issue

17

Just received a reply on my open ticket SUP-63430. This ticket relates to DSCP marked traffic not passing through in the PPPoE/VLAN tagged scenario.
Support asked to me to test something and it looks as though I was able to confirm a possible bug they are seeing in their lab now as well.
It seems that somehow if a packet inside the PPPoE connection has a DSCP mark a VLAN priority mark is attached to the packet. DHCPv6-PD packets (and DHCP packets in general) usually have a DSCP value set.
I do not see this behaviour when configuring the PPPoE link on a bridge which has the required tagged VLAN as it’s PVID and the WAN interface as it’s only tagged member on that VLAN ID. That’s why that workaround seems to be working.

So hopefully we can get this fixed now :slight_smile:

18

I use the following for Bell Canada and it gives me an MTU of 1500:

Interface  | MTU  | L2 MTU
ether1     | 1520 | 1534
br_wan     | 1520 | 1534
pppoe-out1 | no value set (default)
19

IPv6 prefix acquisition over PPPoE was working perfectly with v6.x with this:

/ipv6 dhcp-client add add-default-route=yes comment="IPv6 myISP" interface=pppoe-out1 pool-name= IPv6-myISP-pool1 request=prefix use-peer-dns=no
/ipv6 address add comment="IPv6 myISP" from-pool=IPv6-myISP-pool1 interface=bridge

Now with v7.1 it just shows “Status: searching…” whereas it used to always grab a prefix immediately. I’m not using any VLANs or anything like that, just a very simple setup. What has changed? I’ve tried all the prefix lengths that I can think of, 56, 60, 62, not sure if that’s the problem? I never used to have to enter it before.

20

Have the similar issue on RB5009 - IPv4 dhcp client over bridge over vlan of pppoe. It is a bug of RB5009 I used to test same configuration on software 7.x on hEX S and everything works fine. But on RB5009 is simply not working. How to efficiently create support ticket to mikrotik?
Clipboard03.jpg
Clipboard05.jpg