Dell EMC N1548 Switch stack and ShoreTel VoIP issues

Hi all

I've now spent hours trying to configure our Dell EMC N1548 Switch stack (sw ver. 6.5.1.3) to work with ShoreTel 230 handsets, so I'm hoping someone out there can help. Basically, handsets switch to the Voice VLAN,  but does not get an IP address from DHCP and goes into and endless reboot loop.

Setup:

Switch version:

stack_1#show ver

Switch version:
Machine Description............... Dell EMC Networking Switch
System Model ID................... N1548P
Machine Type...................... Dell EMC Networking N1548P
Serial Number..................... CN0MVV1J1111111R1111A00
Manufacturer...................... 0xbc00
Burned In MAC Address............. 1418.77F5.64B2
System Object ID.................. 1.3.6.1.4.1.674.10895.3066
SOC Version....................... BCM56150_A0
HW Version........................ 2
CPLD Version...................... 16
Image File........................ N1500v6.5.1.3
Software Capability............... Stack Limit = 4, VLAN Limit = 512

Our switches are fairly simple, in that we only have 2 VLANs: the Default (VLAN 1) and Voice (VLAN 2).

We have global voice vlan enabled:

switchport voice vlan

Auto VoIP mode is not used:

stack_1#show switchport voice gigabitethernet 2/0/19

Interface  Auto VoIP Mode Traffic Class
---------  -------------- ------------------
Gi2/0/19   Disabled       6

(all other ports are the same)

IP Helper is configured globally and in the voice vlan:

ip helper-address 192.168.32.51 dhcp
ip helper-address 192.168.32.52 dhcp
...
interface vlan 2
ip address 192.168.40.20 255.255.255.0
ip helper-address 192.168.32.51 dhcp
ip helper-address 192.168.32.52 dhcp
exit

Port config: (note that vlan 1 untagged and pvid vlan 1 does not show in the config as these are default)

switchport mode general
switchport general allowed vlan add 2 tagged
switchport voice vlan 2

DHCP is configured on Windows Server 2012r2 - each scope has this configured: (Data, Voice and TestData as mentioned below)

Option 156 "IP Phone Boot Server"

ftpservers=10.100.0.1, country=7, language=4, layer2tagging=1, vlanid=2

The phone model I'm testing is the ShoreTel 230 (various handsets tried)

 

LLDP is enabled as far as I can tell:

stack_1#show lldp med

LLDP MED Global Configuration
Fast Start Repeat Count: .................... 3
Device Class ................................ Network Connectivity

stack_1#show lldp med interface gigabitethernet 2/0/19

TLV Codes: 0- Capabilities,       1- Network Policy
           2- Extended PSE,       3- Extended Pd


Interface  Link    configMED operMED   ConfigNotify TLVsTx
---------  ------  --------- --------  ------------ -----------
Gi2/0/19   Up      Enabled   Enabled   Disabled     0,1,2,3

Symptoms:

The phone starts up, gets an IP in the VLAN1 range, then "Reconfigures" (meaning it tries to switch to VLAN2) and then it just sits waiting for DHCP forever.

I've noticed that the mac address table has two entries for this handset at this stage:

stack_1#show mac address-table interface gigabitethernet 2/0/19

Aging time is 300 Sec

Vlan     Mac Address           Type        Port
-------- --------------------- ----------- ---------------------
1        0010.4946.196E        Dynamic     Gi2/0/19
2        0010.4946.196E        Dynamic     Gi2/0/19

Attempts:

At first I thought there might be an issue with the fact that we use the Default (1) vlan for data, so I creted another vlan (100), configured it to use the same ip-helpers and also created a new scope for the new VLAN.

The new config looks like this for the switchport (which brings it in-line with Dell's documentation):

stack_1#show running-config interface gi2/0/19

switchport mode general
switchport general pvid 100
switchport general allowed vlan add 100
switchport general allowed vlan add 2 tagged
switchport voice vlan 2

So, I reset the phone and tried again, but the same symptoms persist. The mac address table looks similar again (it gets an IP in vlan 100, then tries to switch to VLAN 2):

stack_1#show mac address-table interface gigabitethernet 2/0/19

Aging time is 300 Sec

Vlan     Mac Address           Type        Port
-------- --------------------- ----------- ---------------------
2        0010.4946.196E        Dynamic     Gi2/0/19
100      0010.4946.196E        Dynamic     Gi2/0/19

 

I've changed the port back to this: 

switchport mode general
switchport general allowed vlan add 2 tagged
switchport voice vlan 2

Running Wireshark on the DHCP servers caught this (note that it does not have any packets since releasing the VLAN1 address):

DHCP packet capture

So please! I'm a bit stuck here and I'm being told "You should have bought Cisco switches!" all the time, so I really need to get this fixed.

Thanks