(how) Are OS-software based driver-level VLAN (DHCP) packets tagged?

Installing and Using OpenWrt
1

Hi

I have a fiber provider offering

Internet : using PPPoE protocol on VLAN10
Video : using IPoE protocol on VLAN30
Voice : using IPoE protocol on VLAN20

My OpenWRT box is a x86_64 mini-PC with 3 separate GigEth interfaces.
No switch hardware.

root@router:~# swconfig list
<nothing>

I correctly get Internet via PPPoE on the eth2.10 (ipv4 and ipv6).

But the Video (which I configured protocol DHCP) does not get an
address assigned on eth2.30.

Discovery packets are sent but no reply is received.

root@router:~# tcpdump -i eth2.30
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on eth2.30, link-type EN10MB (Ethernet), capture size 262144 bytes
00:59:48.767917 IP 0.0.0.0.68 > 255.255.255.255.67: BOOTP/DHCP, Request from 34:5d:9e:d7:fb:30 (oui Unknown), length 300
00:59:51.807906 IP 0.0.0.0.68 > 255.255.255.255.67: BOOTP/DHCP, Request from 34:5d:9e:d7:fb:30 (oui Unknown), length 300
^C
2 packets captured
2 packets received by filter
0 packets dropped by kernel

I looked at capture and I don't see VLAN tag info in the DHCP Request
packets.

Is this expected behavior? Must one and can one explicitly force VLAN
tagging without having hardware switch?

In particular, does one need switch hardware (not just software) for proper tagging control?

Thanks!

2

Try this:

tcpdump -i eth2 -e vlan 30
2 Likes
3

Yes, when you capture on a VLAN interface that VLAN tag is not included/visible, if, as @pavelgl instructs, capture on eth2, you should see all VLAN tags in use there, unless you filter this down to VLAN 30.

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4

@pavelgl @moeller0
Thanks!
When capturing full wire one sees the VLAN tags (also on the DHCP discovery packets).
I'll will need to try to figure out why Video on other VLAN does not get configured...

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5

Make sure you don't have eth2 with no VLAN number anywhere in your config.

Are you intending to route video services yourself or merely bridge it to an ISP provided TV box? In the latter case since there is no hardware switching you'd need to make a kernel bridge attached to a null network (proto none) to pass TV packets between two Ethernet ports.

2 Likes
6

Make sure you don't have eth2 with no VLAN number anywhere in your config.

eth2 is mentioned in device section for eth2.10 (to make interface for internet) and eth2.30 (to make interface for video). Internet works. Video not (yet :-)).

Are you intending to route video services yourself or merely bridge it to an ISP provided TV box? In the latter case since there is no hardware switching you'd need to make a kernel bridge attached to a null network (proto none) to pass TV packets between two Ethernet ports.

I want ISP provided TV box working on Video VLAN. The Internet VLAN gets a fixed public IPv4 address (and a dynamic public IPv6 prefix) on WAN and I have a 192.168.c.d/24 style LAN (and IPv6 delegation/advertisement).

If instead I use ISP provided gateway box, Video VLAN gets a 10.b.c.d style address. Therefore I assumed I had to make the Video interface DHCP client (to get that 10.b.c.d address). But I do not get one...

Not sure what you mean with the Layer2 bridge between the two Ethernet ports. All 3 VLANS are on same physical Ethernet (say, the WAN side of the OpenWRT router) and the LAN side is for the 192.168.c.d/24 subnet.

I think, but I am not sure and still asking around, that Video comes in via 10.b.c.d and is routed (forwarded) to TV Box on 192.168.c.d/24 subnet. These are different subnets (and one may need IGMP proxy for multicast live TV). But... Unlike ISP provided gateway box, OpenWRT box does not get the 10.b.c.d address on VLAN30

7

The ISP's video network may refuse to talk to any device other than their box. I would just bridge it.

1 Like
8

Or try spoofing the MAC address of the ISP box that used to get the DCHP for video.

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9

I did spoof ISP gateway MAC address on eth2.10 to get Internet on Vlan10. Same did not give an address for Video on Vlan30 though. Now I tried to spoof ISP TV Box MAC address on eth2.30 for Video on Vlan30. That does not give an address either. Just out of curiosity I spoofed ISP gateway MAC address on eth2 ... but ISP hung up :slight_smile: so I undid that...

10

So add the Vlan30 for video to the LAN bridge br-lan ?

11

No, use a separate bridge that is only video. That's the whole point of VLANs in keeping networks separate.

1 Like
12

keeping networks separate

Right: L2 bridging the 10.b.c.d and 192.168.c.d made me wonder.

OK, luckily I have 3rd ethernet I can play with (eth1) to attach the ISP TV box to so shall I make a bridge between eth2.30 and eth1.30 or between eth2.30 and eth1 (so TV traffic is tagged or untagged)?

Note however that when I use ISP gateway, TV box got a 192.168.c.64 address (I could then adb into it ... it's an Android). Meaning, under ISP conditions there is some forwarding between VLAN30 (Video) and br-lan.

13

If you remove your router and plug TV box directly into the ONT does it connect to the TV service?

14

If you remove your router and plug TV box directly into the ONT does it connect to the TV service?

I have not tried yet ... sorry

But, I got some help from local ISP related forum ... I needed several ISP vendor equipmant specific DHCP options and now I get the reruired 10.b.c.d/16 address.

Next I need to arrange multicast forwarding and igmp proxy for live TV.

Someone on local ISP related forum has a working setup and I will ask his config to figure out topology for unicast and multicast and the VLAN assignments and the NAT.

update: meanwhile ISP IPTV works

Thanks for all help!

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