No Internet Connectivity in VLAN created with external DHCP server

This thread has been locked for further replies. You can start a new thread to share your ideas or ask questions.

No Internet Connectivity in VLAN created with external DHCP server

This thread has been locked for further replies. You can start a new thread to share your ideas or ask questions.
No Internet Connectivity in VLAN created with external DHCP server
No Internet Connectivity in VLAN created with external DHCP server
2022-06-23 00:14:52
Model: ER605 (TL-R605)  
Hardware Version: V1
Firmware Version: 1.2.1 Build 20220512

I've created a few interface VLANs for groups of related devices and it's been relatively straightforward.

Internet connectivity has never been a problem.

 

Today, I setup a VLAN to test a configuration with DHCP not hosted on the router.

The reason behind this all is that I want local DNS and I'd like DHCP & DNS to be hosted on the same box to avoid having to correlate bits of information across multiples machines.

So I setup a NUC with Ubuntu, created a virtual NIC for the VLAN, and configured dnsmasq to handle DHCP/DNS for that VLAN/subnet only.

 

On the controller side, I created a TEST VLAN as usual (VLAN ID included in the fixed part of the range).

I disabled the DHCP server and specified a 10.x.x.2 address for the legal DHCP server (that's the address of the virtual NIC on the NUC).

I used the typical 10.x.x.1 for the gateway in the subnet.

 

Then I changed the profile of the switch port used by my test machine and released/renewed DHCP.

All went fine. I got an IP in the proper range, the Default Gateway is properly set to 10.x.x.1. The subnet mask is fine, as is the DNS domain.

 

BUT I can't ping that .1 address (gateway/router). I can ping the .2 address (DHCP/DNS server) though.

Somehow, the physical router does not seem to act as a gateway in this specific configuration (or maybe at another IP that I don't know how to discover).

In all my other VLANs, I can ping 10.y.y.1 from devices in that VLAN, as expected.

I attribute the lack of internet connectivity to the absence of a gateway at this 10.x.x.1 address. If the gateway picked another one (I didn't see a DHCP request for any other device), I don't know how to find it.

 

What am I missing?

  0      
  0      
#1
Options
4 Reply
Re:No Internet Connectivity in VLAN created with external DHCP server
2022-06-23 07:14:20

  @EricPerl Some people shared the experience before, but not sure why I cannot open that page anymore. Related post

 

About your configuration, what I suggest is to try enable the router DHCP(on the controller) first, and double check if your computer can receive correct IP from the router. It is used to test your VLAN settings and port frpfile settings. Make sure the port connected to your computer and virtual NIC (DNS/DHCP server) are on the correct VLAN.

  1  
  1  
#2
Options
Re:No Internet Connectivity in VLAN created with external DHCP server
2022-06-23 21:07:29

@Somnus,

 

Thanks for pointing me at that post. I had not seen it. The forum search is not great...

 

I have access to the external link on scribd. Maybe you no longer have access if you let your 30 day "trial" expire (could just be a matter of deleting some cookies).

I've read through it twice and I find it difficult to follow.

One of the reasons is that the explanations (192xxx) and the screenshots (10xxx) are using different subnets.

I think I somehow can get around this given the convention used to encode the vlan in the subnet.

The other reason is that I can't figure out what IP the router occupies.

 

I'm mentioning the author @jwaltrip here and maybe he can shed some light on that.

In any case, I thank him for the walkthrough. It give me something to try...

I would definitely like something incremental that I can test in a separate VLAN on top of the state of say FAQ 3091 (How to configure Multi-Networks & Multi-SSIDs on Omada SDN Controller | TP-Link). That's pretty close to what I have. I'd rather not break what I already have until I know how to move forward.

 

One obvious difference between my approach and the one in this walkthrough is the use of DHCP relays (I didn't use them).

The reason behind this is that I couldn't figure out how to configure my DHCP server to serve the correct range.

As of today, the only piece of information a client "inherits" at the very beginning is the VLAN ID that's added by the switch based on the port the client is connected to.

I have no clue how that is transferred thru a DHCP relay. It's possible the relay ends up in the relayed DHCP_DISCOVER message.

I guess I can enable full logging on the DHCP server and investigate.

It's even more baffling given the fact that the DHCP server of the walkthrough is in a VLAN (SERVERS) and is likely getting untagged traffic.

In my case, I added a virtual NIC for the VLAN subnet to the DHCCP/DNS server and the server sits in the native LAN at this point (I have not yet re-enabled the MGMT VLAN).

 

In any case, the DHCP/DNS aspects seem to work very well.

As I flip the profile on the port that my test machine is connected to, it gets a proper IP in the correct VLAN/subnet.

The only thing that doesn't work is internet connectivity when IP is from the external DHCP server.

And I attribute that to the fact that the IP is indicate in the gateway box of the interface VLAN is not reachable within that VLAN.

No device seems to have claimed it.

In my other VLANs (per FAQ above), I can ping that IP from all devices in the VLAN. I assume it's assigned to the ER605 router (but maybe my mental model is wrong here).

  2  
  2  
#3
Options
Re:No Internet Connectivity in VLAN created with external DHCP server
2022-06-23 21:35:23

D'OH!

I just found my mistake after going through some articles related to this post.

As I looked back at my configuration, I noticed I did not check the proper 'LAN interfaces' during network creation...

I only had WAN/LAN1 checked, not the LAN one and that's the one that my main switch is connected to.

 

I fixed this and voila. Internet connectivity restored in my TEST VLAN.

While I realize that it may not be a configuration for everyone (I could tinker with virtual interfaces on my DHCP router), I'd argue it's a relatively simple configuration when compared to the one outlined by jwaltrip. And I can incrementally switch my other VLANs to target my DHCP/DNS server (create virtual interface, add DHCP range config, update network interface in Omada).

 

Thx all that got me looking around.

  2  
  2  
#4
Options
Re:No Internet Connectivity in VLAN created with external DHCP server
2022-08-16 06:05:22

Sorry. I have not checked in a 2qhile.

 

Do oyu still need assistance?

  0  
  0  
#5
Options