N3000 DHCP with voice and data VLANs

Question

Hello all,

I know what I'm trying to do is theoretical extremely simple and basic, but I've spent an inordinate amount of time trying to figure this out and am getting nowhere.

What I have is a very simple test situation with a voice VLAN with Shoretel phones, with VLAN 1 as the data VLAN and 20 as the Voice VLAN.

DHCP Server connect to switchport #1:
Windows Server 2008 (10.1.10.23 /23)
Scope #1 (Data VLAN)

10.1.10.100-200 /23
003 Router 10.1.10.98 (the switch interface for VLAN 1)
006 DNS Servers 10.1.10.4,10.1.11.9
015 DNS Domain Name company.com
156 Shoretel "ftpservers=10.1.10.80,country=1,language=1,layer2tagging=1,vlanid=20"

Scope #2 (Voice VLAN)

2.2.2.100-200 /24
003 Router 2.2.2.1 (the switch interface for VLAN 20)
006 DNS Servers 10.1.10.4,10.1.11.9
015 DNS Domain Name company.com
156 Shoretel "ftpservers=10.1.10.80,country=1,language=1,layer2tagging=1,vlanid=20"

The way Shoretel phones work is they come up untagged, grab a DHCP address, look at option 156, then release their address. If option 156 specifies VLAN tagging, it turns that on and reboots with the new tag.

So here's my very, very basic switch config:

vlan 20

name "Voice VLAN"

exit

ip routing

interface vlan 1

ip address 10.1.10.98 255.255.254.0

exit

interface vlan 20

ip address 2.2.2.1 255.255.255.0

ip helper-address 10.1.10.23

interface Gi1/0/1 - no config / default access mode VLAN 1

description "DHCP server"

exit

interface range Gi1/0/2-22

switchport mode general

switchport general allowed vlan add 20

exit

On port #5, I have a laptop which receives a proper VLAN 1 DHCP address.

On port #7, I have a Shoretel phone with a computer daisy-chained off it. This computer receives a VLAN 1 DHCP address just fine.

On port #9, I have a Shoretel phone with no computer attached.

With both phones, they initially boot up and get VLAN 1 addresses. They they say "reconfiguring network", which is what they do when they switch VLAN, but then they just sit there requesting a DHCP address. I've tried "vlan add 20" and "vlan add 20 tagged" both, with no change in results.

The DHCP server log shows the initial VLAN 1 address assignments and releases, but that's it.

show ip helper-address shows:

Interface: Vl20

UDP Port: Default

Discard: No

Hit Count: 211

Server Address 10.1.10.23

What incredibly simple and obvious thing am I missing here? TIA

DELL-Josh Cr · Answer

Hi hobdey,

Did you use the voice vlan commands to configure the tagging? Page 836 ftp://ftp.dell.com/Manuals/all-products/esuprt_ser_stor_net/esuprt_networking/esuprt_net_fxd_prt_swtchs/networking-n3000-series_Deployment%20Guide4_en-us.pdf

This is for an older switch but the ideas are the same http://en.community.dell.com/techcenter/networking/w/wiki/configuring-dell-powerconnect-55xx-series-switch-voice-vlan

Is it configured for LLDP-MED Page 15 http://support.shoretel.com/kb/downloads/AN10326.pdf

If you change the PVID on the general port attached to the phone does it get an IP from VLAN 20? You may want to try not using VLAN 1 for the untagged and move that to a different VLAN.

DyerM · Answer

Maybe a stupid question... but is this line in your config?

dhcp l2relay vlan 20

DHCP is a UDP broadcast... for that to cross to your DHCP server you have to relay it using the command above or by doing a DHCP l2relay all. (which would relay all dhcp requests regardless of vlan)

DELL-Josh Cr · Answer

Changing the pvid was just to test to make sure it can pull an address that way. It seems to be getting stuck somewhere in the DHCP transition. Testing with a static ip on the phone and making sure if everything aside from dhcp is configured as it should be works, can eliminate other things causing the problem.

hobdey · Answer

Well, I tried the 'voice vlan' commands, but they didn't do anything.  Kind of didn't think they would because they pertain more to QoS than DHCP. I'd seen that particular article for the 5500-series before, but it also doesn't really address DHCP and the software must have changed quite a bit because the oui-table stuff doesn't appear to even be available on the N3000. What I am afraid of, and I suppose it's not REALLY a big deal, is that this switch operates like an article I read on the 6800-series switch indicating that you can't use VLAN 1 in this manner and that, like you suggest, I'd need to resign VLAN 1 to management and use say VLAN 10 for my data.  I'm going to give that a shot and see where I end up. Correct me if I'm wrong (very, very likely BTW), but if I put a PVID on one of my phone ports, the initial boot of the phone would be untagged and therefore be on VLAN 20 which seems to be part of the problem.  Plus any computer plugged into the phone would always be untagged traffic and then get assigned to VLAN 20 by default, wouldn't it?

hobdey · Answer

After a lot of playing around with this, the answer seems to have centered around not being able to use VLAN 1 for data after setting up another VLAN.  When I relegated VLAN 1 to being unused and moved data over to VLAN 10, I was able to get everything working just fine.

ELFinMagic 75 · Answer

What version of firmware are you on?  I know that some of the older firmware has a DHCP helper bug, and you may need to upgrade the firmware.  On some switches you also need to enable the IP Helper globally,  so if firmware upgrade doesn't work then try putting the helper address on global config as well as on the VLAN.

ELFinMagic 75 · Answer

Also, this configuration will only work if you hard set your phones to tag VLAN 20.  If you want the switch to auto detect the phone and put it on VLAN 20 you will need to enable voice vlan globally and tell the ports that voice vlan is 20/

Networking General

N3000 DHCP with voice and data VLANs

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