VLAN other than 1 not working with Atheros NIC on Acer Laptop and TP-Link switch

[alexandruort]

Hi!

Devices involved: Acer Aspire 8943G, smart switch TP-Link TL-SG2452.

Recently I had to separate three hosts on a VLAN. Almost all the ports of the switch are on VLAN 1, expect three of them for which I've set up pvid=2 untagged and I've excluded them from VLAN 1. Two hosts communicate through the switch but one laptop, Acer Aspire 8943G, doesn't behave as expected.

I've swiched ports with no success. I've updated the driver of the nic, an Atheros AR8151. I've also tried with a live CD of Ubuntu. Still, no success. Another laptop (with another configuration, different model) works well connected in the ports of the switch of vlan 2.

What is strange is that:
1. On a port of vlan 1 the laptop can communicate with the other hosts from vlan1.
2. Beeing connected to a vlan2 port the laptop RECEIVES its ip configuration through dhcp from a modem. No other communication exists afterwards.

I can't figure out this problem. Anyone, do you have a clue of what's happening here?

Thank you.

Alex

 

[alexandruort]

Sorry to pop up this thread by myself. Does anyone have a clue what's happening here?

Alex

 

[bill001g]

Unless you are using vlan tags on the port to the PC you should have to do nothing to the pc configuration.

You have to think of vlans as creating completely separate physical switches. There really is nothing special about the ports when you set them to untagged. Since there are no tags the end device can not even detect that you are using vlans. Your design would be exactly the same as if you had physical switches.

Hard to say, I am assuming you actually have 4 ports. 3 for the end devices and 4th that you have the modem you are using getting the DHCP from.

This is a pretty simplistic config so it almost can't not work so it has to be something strange causing it.

 

[alexandruort]

Yes, it is a very simple setup. I also know that untagged frames are just ... frames. I'm sure the config of the smart switch is not wrong because another laptop connected in the same port of the same switch using the same cable does have access to the network and to the internet. It is that specific Acer laptop that doen not work after receiving it's dhcp lease. It's at least strange. That's why I asked on this forum.

What would it work on vlan 1 and not on vlan 2? Why would receive it's lease and stop communicating afterwards?

Alex

 

[bill001g]

All I can think of is it is getting a IP for the wrong network. If it uses IP addresses from vlan 1 but attempts to use them on vlan 2 it won't work.

Because it can get ip addresses from the dhcp server it means it must be talking to it even though those are all broadcast messages.

 

[alexandruort]

I'm sure the connections are fine. As a proof the other laptop behaves as expected. If a replace one laptop with another there is no problem at all. So it's not the switch or it's configuration nor the connections.

Unfortunatelly, I cannot replace the Acer laptop. Hope finding a solution with your help also.

Alex

 

[bill001g]

Are you sure you are getting the proper IP address. If for example you have vlan 1 defined as 192.168.1.x addresses and vlan 2 as 192.168.2.x addresses if a pc would happen to get a ip on the wrong vlan it will not work correctly.

It could get the wrong ip if there is something incorrect in the dhcp server or the pc is using some form of static ip.

 

[alexandruort]

Finally, it got this thing working by setting the ip with manual configuration. The address from the dhcp lease was fine, though. I verified with a usb-to-lan adapter which worked fine. I don't know what was wrong on that interface with the lease but now it works.

Alex