Take the 2-minute tour ×
Super User is a question and answer site for computer enthusiasts and power users. It's 100% free, no registration required.

I have access to a Huawei ONT echolife hg8012H, input fiber optic, output 1GibE Ethernet, and a RF TV coaxial connector.

The working 3play setup is something like this:

 [fiber optic]
       |
       |
   Huawai ONT
       |
      / \
     |   [RF connector]---> TV (Analog)
     |
 [1GigE Ethernet Port]
     |
     |
 1GigE switch
    / \
   |   `-- FreeBSD (vlan 100) 
   |
   |
 3play Thomson TG784n router          
     |
    / \__ [TelePhone]
   | 
[LAN (Natted) ports]
   |   |  |   |
  PC1 PC2 PC3 PC4

This configuration help me to have 2 networks, one served by the Thomson TG784n router, and other for the FreeBSD server.

I could connect the FreeBSD server, because I knew the VLAN ID.

But suppose that I have only the ONT and the FreeBSD server, example:

 [fiber optic]
       |
       |
   Huawai ONT
       |
      / \
     |   [RF connector]---> TV (Analog)
     |
 [1GigE Ethernet Port]
     |
     |
  FreeBSD 

If I don't know anything about the VLAN ID's, I just know it works (service is available) but only after specifying the proper VLAN ID I would be available to get an IP via DHCP, how to find or discover, available ID's ?

Requesting an IP via DHCP without specifying an VLAN, doesn't work, I must specify a VLAN ID in order to get a routed IP.

The ONT web interface just displays info about the Fiberoptic and the status of the link, but nothing related to the VLAN's.

Any ideas?

share|improve this question

migrated from serverfault.com Mar 21 at 9:49

This question came from our site for professional system and network administrators.

1 Answer 1

I cannot comment for clarification but what do you mean when you say "only after specifying the proper VLAN ID" specify it where?

Typically you'd only need to specify your VLAN if that VLAN is being tagged or expected to be tagged already coming into the switch. If that's the case you could use Wireshark or another sniffer to view the traffic that is already being passed to see what those packets are being tagged. It should be tagged with one or more VLANs.

Really DHCP has no concept of VLAN, there are DCHP Options that can hand out VLAN information (it's used in VoIP sometimes) but generally speaking DHCP only cares about the subnet that the request comes from.

share|improve this answer
    
If mean that if I attach the network cable to the OTN and ask for an IP via DHCP I don't get nothing, the only way I can make it work is to first configure the switch or computer to attach to a specific VLAN ID and only then I can make other layers to work including dhcp/routing etc. Now, how to sniff traffic with wireshark while the only device attached is a PC/Server that doesn't know the VLAN tags ? –  nbari Mar 20 at 9:46
    
You don't need to know the VLAN tag to sniff traffic. Devices send broadcasts ALL THE TIME and those broadcasts will be tagged. –  MysticRyuujin Mar 20 at 23:54

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.