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Deskphones - VLAN Configuration of Polycom Phones | RingCentral

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SummaryVLAN Configuration for Polycom phones.
Last Modified: September 6, 2018


1. Introduction

This article provides and overview of the boot order of Polycom phones and options for VLANs provisioning. 


2. Acronyms

The following acronyms are used in this document:
  CDP  Cisco Discovery Protocol  LLDP  Link Layer Discovery Protocol
  DHCP  Dynamic Host Configuration Protocol  VLAN  Virtual Local Area Network
  DNS  Domain Name Server  VLAN ID  Virtual Local Area Network Identifier
  IP  Internet Protocol  

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3. General Phone Request Process for VLAN and IP Information

A Polycom IP phone can operate on a separate Voice-tagged VLAN. The Ethernet Switch connected to the phone must be configured must be configured properly to use VLANs. A phone can retrieve its Voice VLAN information by four different methods:
• LLDP – Link Layer Discovery Protocol
• CDP – Cisco Discovery Protocol
• DHCP – Dynamic Host Configuration Protocol
• Statically configured on the phone

The following process is executed by Polycom phones to receive Voice VLAN information:
1. When the phone boots, it first sends an LLDP message to the Ethernet switch requesting a VLAN ID with the Voice VLAN ID
2. If LLDP responds with the VLAN ID, then a DHCP request for IP address and 160 Option is sent on the tagged Voice VLAN ID
3. If no LLDP response occurs, then a CDP message is sent to the switch requesting Voice VLAN ID
4. If CDP from the switch responds with Voice VLAN, a DHCP request for IP address and 160 Option is sent on the tagged Voice VLAN
5. If no CDP response is received, a DHCP request is sent on the Data VLAN for the Voice VLAN DHCP Option and IP information

4. DHCP Server Voice VLAN Provisioning

To configure a Voice VLAN the following items need to be provisioned on the DHCP server:

1. LLDP/CDP must be disabled on the Ethernet Switch port when using DHCP to configure the Voice VLAN.
2. DHCP Options required by the phone that must be defined in the Data VLAN Scope of the DHCP server (click to view the Wireshark file) are:
• 1 Subnet Mask
• 3 Router (Default Gateway) IP Address
• 6 Domain Name Server (DNS) IP address
3. Optionally, four different DHCP options can be used to configure a Data VLAN in the DHCP Data scope.
• One of the following options may be used (sometimes an option does not work and a different one has to be selected): Options 128, 144, 157 or 191
4. The VLAN must be configured as VLAN-A=x; -- where x = Voice VLAN number. Example:

VLAN-A=10; -- set Voice VLAN to 10, VLAN-A must be with capitalized letters and must end with a semi-colon.

5. Define a Voice VLAN Scope with the proper IP and Options 1, 3 and 6.
6. Optionally, the following provisioning service can be configured in Option 160 in the DHCP Voice Scope:
• https://pp.ringcentral.com/pp

5. Phone Voice VLAN DHCP Request-Response Process

The VLAN request-response process including reboots is as follows:
1. IP Phone performs DHCP request on the Data VLAN (No VLAN tagging)
2. DHCP Server responds with option to set VLAN (e.g. VLAN-A=10;)
3. IP Phone releases previous DHCP Data VLAN IP address
4. IP Phone reboots after receiving VLAN option
5. IP Phone requests Voice VLAN DHCP scope (with VLAN Tagged to 10)
6. DHCP Responds with new IP address for the Voice VLAN
7. Optional - Use Option 160 with Provisioning Service URL https://pp.ringcentral.com/pp (Section 6)
8. Phone continues boot process
9. Phone contacts Provisioning Server on the Voice VLAN

6. DHCP Option for Connecting to the Provisioning Service

To use any IP phone, it must be provisioned in the RingCentral Service Portal identifying the phone’s MAC Address. Polycom phones can be obtained in two ways:

• Polycom phones purchased from RingCentral are already configured with the link https://pp.ringcentral.com/pp pointing to the RingCentral Provisioning service. After receiving the IP address via DHCP, the phone will connect to the RingCentral Provisioning server and provision the phone appropriately.

• If the Polycom phone is not purchased from RingCentral and reused from a previous VoIP deployment, then it does not have the provisioning server configured. In that case DHCP can be used to provide the RingCentral provisioning service:
Create DHCP Option 160 on the DHCP Server for the IP Address scope servicing the IP Phone
Set DHCP Option 160 to an ASCII string equal to: https://pp.ringcentral.com/pp
Perform a factory reset of the Polycom phone via the phone display

7. Polycom Boot Process – Summary

The phone boot process is summarized as:
• LLDP to configure Voice VLAN – See switch manufacturer documentation on how to configure LLDP for the Voice VLAN
• CDP to configure Voice VLAN – See switch manufacturer documentation on how to configure CDP
• DHCP Option 128, 144, 157, 191 to configure Voice VLAN
VLAN-A=10; -- to set Voice VLAN to 10, must be in CAPS and must end with a semi-colon, no white spaces
• Place option in the Data DHCP Scope
• DHCP Option 160 to configure RingCentral Provisioning Service: https://pp.ringcentral.com/pp
• Place option in the Voice DHCP scope
• More information can be found in the PolyCom UC Software Administration Guide

8. Wireshark Trace of the DHCP Discovery Process

• Frame 1 – IP Phone DHCP Discover: Parameter request asking for Options 191,157,144, 128 and 160
• Frame 2 – DHCP Offer: Option 160 (Provisioning Server) and 144 (VLAN Info) being returned
• Frame 5 IP Phone sending DHCP Release: Release of old IP address on Data VLAN
• Frame 6 IP Phone DHCP Discover on Voice VLAN: New Discover on the Voice VLAN requesting option 160.
• Frame 7 – DHCP Offer: Option 160 for the Provisioning server

file: polycom dhcp boot process with vlan-2.pcapng

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See Also 
Expanded Version: RingCentral Network Requirements and Recommendations 
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