Author Topic: No DHCP on accessport w/ VLAN tag  (Read 2006 times)

iotkb

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No DHCP on accessport w/ VLAN tag
« on: June 22, 2018, 04:36:25 PM »
I don't know if I should bump this old thread or that I just should open a new one, but the problem I'm facing is quite similar to what's being described here:
Today I received a new Pockethernet, when I enter a valid VLAN ID as outgoing VLAN Tag, I get DHCP information.
When I don't enter a valid VLAN ID, I'm not getting DHCP information

The port configuration is as follows:
Switch: HP Procurve 2910 J9148A with latest firmware
Switch: HP Procurve 2920 J9728A with latest firmware
(both switches show the same problem)
VLAN 15 untagged
VLAN 25 tagged (voip)

Outgoing VLAN Tag selected with VLAN ID 25:
- switch shows MAC-address in VLAN 25
- DHCP information received
- while running traffic sampling, I see traffic from both untagged VLAN 15 and tagged VLAN 25

Outgoing VLAN Tag unselected:
- switch shows MAC-address in VLAN 15
- no DHCP information
- while running traffic sampling, I see traffic from both untagged VLAN 15 and tagged VLAN 25.

Although I didn't expect anything, I just ran some tests:
Outgoing VLAN Tag selected with VLAN ID 15, no DHCP information
Outgoing VLAN Tag selected with VLAN ID 0, no DHCP information
Outgoing VLAN Tag selected with VLAN ID -1, no DHCP information

I also tried different locations, connected to different switches, different VLAN's. Other devices like computers, laptops or VOIP telephones get the right DHCP information. Even when I'm putting the PE behind a VOIP-phone, the PE does not get any DHCP information.

The Pockethernet is running HW version 06, firmware 29
Android app version 2.8a
iPhone app version 2.61

I hope anybody can help me or give me any directions how to debug this.
« Last Edit: May 28, 2019, 02:46:50 PM by iotkb »

iotkb

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Re: No DHCP on accessport w/ VLAN tag
« Reply #1 on: July 19, 2018, 04:36:02 PM »
Bump... Is there anybody out there who might be able to help me fix this or at least help me debug this issue so the developers might fix it?

CoolComputerGuy

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Re: No DHCP on accessport w/ VLAN tag
« Reply #2 on: August 30, 2018, 09:59:09 PM »
Try setting the DHCP timeout, under settings, to 60sec. This worked for me.
Update for clarification: I was having issues getting an IP via DHCP from certain switches. I was not attempting to use the Outgoing VLAN Tag feature.
« Last Edit: August 31, 2018, 09:53:22 PM by CoolComputerGuy »

iotkb

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Re: No DHCP on accessport w/ VLAN tag
« Reply #3 on: August 31, 2018, 01:39:35 PM »
Thnx!

Unfortunately it doesn't help. But it made me investigate further and this is what I noticed:
We're running Windows 2012R2 DHCP in Load Balanced failover. The logging reports:
36,08/31/18,13:14:17,Packet dropped because of Client ID hash mismatch or standby server.,[subnet],,[mac-address],,0,6,,,,,,,,,0

This pointed me to several articles spread all over the mighty interwebs, most of them somehow pointing at the failover configuration. It seems to happen especially with non-Windows devices. Although I'm still far away from fixing it permanently, I am able to fix it temporarily by switching from 'Load Balanced' to 'Hot Standby'

This article is pointing at a specific value in DHCP Discover packets which might be missing. (I can't confirm that yet)
« Last Edit: August 31, 2018, 01:41:06 PM by iotkb »

JRBlood

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Re: No DHCP on accessport w/ VLAN tag
« Reply #4 on: August 31, 2018, 07:58:12 PM »
I just posted in an older thread about this issue. Take a look: https://forum.pockethernet.com/index.php?topic=154.msg1524#msg1524

In short, do not check "Outgoing VLAN Tag" when running tests. It should only be used, along with the correct VLAN #, when testing for VLAN connectivity.
« Last Edit: August 31, 2018, 09:15:27 PM by JRBlood »

iotkb

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Re: No DHCP on accessport w/ VLAN tag
« Reply #5 on: May 28, 2019, 11:06:17 AM »
Unfortunately no progress on this issue.

FW: 31 beta
App: Android 31a (side loaded from https://forum.pockethernet.com/index.php?topic=348.0)

« Last Edit: May 28, 2019, 02:42:13 PM by iotkb »

jhoughton

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Re: No DHCP on accessport w/ VLAN tag
« Reply #6 on: July 11, 2019, 03:54:28 PM »
Unfortunately no progress on this issue.

FW: 31 beta
App: Android 31a (side loaded from https://forum.pockethernet.com/index.php?topic=348.0)


Didnt JRBLOOD's post help?


Lets just say you have four ports on your switch.  Port 1 is what connects back to your main network and is VLAN1, then port 2 is VLAN15 and port 3 is VLAN and port 4 is whatever we want.

First things first, if your switch does in fact run back to some "core" switch, you will have to know not only what port your switch is using to run back to the core, but also the port on the core that is connected to.  You need to know, because that core switch would have to have tagged, all the VLANS that YOUR switch is using.

Port 1 VLAN 1 would be UNTAGGED (this is your main VLAN lets say)
Port 2 would be TAGGED
Port 3 would be TAGGED
and Port 4 you could make it TAGGED for any of the above VLANS.  Lets just say it was UNTAGGED, that would in turn make it VLAN1


If you plugged your pocketethernet (PE) into ANY of those ports you, i dont believe you DONT want to Tag Outgoing VLAN Tag, if you did, you would either not be able to get out of the switch, but it may only show you the VLAN you are on.  By UNTAGGING it, you are allowing, you are allowing traffic to pass though not onyl that port, but ACROSS the VLAN, because you have the main port untagged, and the VLANS you want to get across the network TAGGED.

Again, this all relies on where your main network cable goes.  If it runs from your switch to a "core" switch, and it doesnt have the same VLANS on it, and the port you are in, it tagged for anything other than VLAN1, no traffic will get from your switch to the core, and the PE will onyl show what VLANS you have on your switch, and the fact your wont get DHCP.

Hope the above helps, but would be interested if your switvch does in fact run to a core switch, if so i might be able to help.  But remember no tagging outbound vlan on the PE.

Best,
Jason.

iotkb

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Re: No DHCP on accessport w/ VLAN tag
« Reply #7 on: July 12, 2019, 10:52:42 AM »
Unfortunately JRBLOOD's post didn't help.

I don't know if I understand you right, so perhaps my openingspost needs some clarification:
- All our switchports *always* have an untagged VLAN. Factory default is VLAN 1
- We configure all operational switchports for a separate data VLAN, untagged - for example untagged VLAN 15
- We configure all our switchports with IP-phone with pass through for a separate voice VLAN, tagged - for example VLAN 25

So this is a typical configuration of a switchport with IP-phone with pass through towards a desktop computer:
- Untagged VLAN 15
- Tagged VLAN 25

Basically this is what happens:
- All data traffic from the computer is passed through by the IP-phone towards the switch with no VLAN tag set in any packet
- All voice traffic from the IP-phone itself has the VLAN tag set in every packet and then directed towards the switch
- The switch reads the value in VLAN tag of each packet
- If no VLAN tag set, the switch redirects the packet to VLAN 15
- If VLAN tag is set to 25, the switch redirects the packet to VLAN 25
- If VLAN tag is set to something else, the switch disregards the packet