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About VLAN
VLAN (Virtual Local Area Network) is used to logically divide a physical network into several broadcast domains. VLAN membership can be configured through software instead of physically relocating devices or connections. VLANs address issues such as scalability, security, and network management. Routers in VLAN topologies provide broadcast filtering, security, address summarization, and traffic-flow management. By using VLANs, one can control traffic patterns and react quickly to relocations. VLANs provide the flexibility to adapt to changes in network requirements and allow for simplified administration.
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As voice traffic is delay and jitter sensitive for the IP phone, it requires higher priority over data traffic to reduce delay and packet loss during transmission. To simplify configuration procedures and better manage voice transmission policies, the connected switch can be configured to provide voice VLAN function and transmit the voice traffic of the IP phone in a dedicated VLAN, called voice VLAN.
Voice VLAN is a special access port feature of the switch which allows IP phones to be automatically configured and easily associated with a logically separate VLAN. This feature provides various benefits, but one particular benefit is that when voice VLAN is enabled on a switch port, this port is also enabled to allow simultaneous access for a PC. This feature allows a PC to be daisy chained to an IP phone and the connection for both PC and IP phone to be trunked through the same physical Ethernet cable.The purpose of VLAN configurations on the IP phone is to insert tag with VLAN information to the packets generated by the IP phone. When VLAN is properly configured for the ports (Internet port and PC port) on the IP phone, the IP phone will tag all packets from these ports with the VLAN ID. The switch receives and forwards the tagged packets to the corresponding VLAN according to the VLAN ID in the tags described in IEEE Std 802.3. 
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Major Benefits of Using VLANs
VLANs offer many benefits that are not found in typical LANs. Major benefits of
segregating IP phones into VLAN(s) are listed as below:
Performance Enhancements: VLAN is used to minimize the broadcast domain. Creating smaller domain for IP phone can reduce overhead and limit resource utilization. Additionally, less traffic will need to be routed, and the latency added by routers will be reduced.
Ease of Administration: Much of the cost associated with network additions and relocations can be saved through the use of VLANs. IP phone can be shifted from one workgroup or department to another without installing new network cabling and reconfiguring hubs or routers.
Security: VLANs can be used to create secure user groups and prevent others outside of the broadcast domain from receiving sensitive data of the IP phone. They can also be used to enhance firewall functions and restrict network access for one or more users. By segregating IP phones into VLANs, security filters can be implemented in the network to prevent the IP phones from receiving unnecessary traffic from other devices. This helps prevent disruption due to DoS attacks or attempts to compromise the devices. It also allows locking down access to configuration and servers to only allow access from the IP phones.
Htek IP Phones Compatible with VLAN
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LLDP (Link Layer Discovery Protocol) allows Ethernet network devices to receive and/or transmit device-related information to directly connected devices on the network that are also using the protocol, and store the information that is learned about other devices. Information gathered with LLDP is stored in the device as a management information database (MIB) and can be queried with the Simple Network Management Protocol (SNMP) as specified in RFC 2922. LLDP transmits information as packets called LLDP Data Units (LLDPDUs). An LLDPDU consists of a set of Type-Length- Value (TLV) elements, each of which contains a particular type of information about the device or port transmitting it.
Each of the TLV components has the following basic structure:
Type | Length | Value |
7 bits | 9bits | 0-510 octets |
LLDP supports advertising the following TLVs:
Mandatory LLDP TLVs: Chassis ID, Port ID, and Time to Live (TTL) are included in an LLDPDU by default.
Optional LLDP TLVs: System Name, System Description and so on, the phone sends the optional TLVs along with the mandatory TLVs in an LLDPDU.
Organizationally Specific TLVs: MAC/PHY Configuration/Status and Port VLAN ID, which are defined in IEEE Standard 802.3 and 802.1 respectively.
The LLDP frame ends with a special TLV, named end of LLDPDU in which both the type and length fields are 0.
LLDP -MED
LLDP -MED (Media Endpoint Discovery) is published by the Telecommunications Industry Association (TIA). It is an extension to LLDP that operates between endpoint devices and network connectivity devices. LLDP -MED specifically provides support for voice over.
IP (VoIP) applications and provides the following capabilities:
Capabilities Discovery—allows LLDP -MED endpoints to determine the capabilities that the connected device supports and has enabled. It can be used to indicate whether the connected device is a phone, a switch, a repeater, etc.
Voice VLAN Configuration—provides a mechanism for a switch to notify a device which VLAN to use, which enables ?plug and play? networking.
Power Management—provides information related to how the device is powered, power priority, and how much power the device needs.
Inventory Management—provides a means to manage device and the attributes of the device such as model number, serial number, software revision, etc.
Location Identification Discovery—provides location information from the switch to the device when making an emergency call.
In addition to the TLVs advertised by LLDP, LLDP -MED also supports advertising the following TLVs:
LLDP -MED capabilities TLV
Network policy TLV
Power management TLV
Inventory management TLV
Location identification TLV (not supported by IP phones)
It should be noted that either LLDP or LLDP -MED—but not both—can be used at any given time on an interface between two devices
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TLVs supported by IP phones are summarized in the following table:
TLV Name | TLV Type | Description |
Mandatory TLVs |
Chassis ID | Specifies the IP address of the sending port. | |
Port ID | Specifies the MAC address of the IP phone. | |
Time To Live | Specifies the life of the transmitted information on the IP phone. The default value is 180sec. | |
End of LLDPDU | Marks the end of the TLV sequence in the LLDPDU. No further processing of TLVs after this is necessary. This is a mandatory TLV and therefore must be present at the end of the data stream. | |
Optional TLVs |
System Name | Specifies the administratively-assigned name for the IP phone. | |
System Description | Specifies the description of the IP phone. | |
System Capabilities | Specifies the supported and enabled capabilities of the IP phone. | |
Port Description | Specifies the description of the sending port. | |
IEEE Std 802.3 Organizationally Specific TLV | MAC/PHY Configuration/Status | Specifies duplex and bit rate settings of the IP phone. |
LLDP -MED TLVs |
Media Capabilities | Specifies the MED device type of the IP phone and the supported LLDP -MED TLV type can be encapsulated in LLDPDU.
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Network Policy | Specifies the port VLAN ID, application type, L2 priority and DSCP value. | |
Extended Power-via-MDI | Specifies power type, source, priority and value. | |
Inventory – Firmware Revision | Specifies the firmware revision of IP phone. | |
Inventory – Serial Number | Specifies the serial number of IP phone. | |
Inventory – Manufacturer Name | Manufacturer name of IP phone. | |
Inventory – Model Name | Specifies the model name of IP phone. | |
Asset ID | Specifies the asset identifier of IP phone. |
Configuring LLDP Feature
LLDP is disabled on IP phones by default. You can configure LLDP via web interface, LCD Interface or using the configuration file. You can also configure the sending frequency of LLDP packet. The default sending frequency is 120s.
To configure LLDP feature via web interface:
1. Log into the web interface
(The default administrator user name and password are both "admin")
2. Click on Network->Advanced.
3. In the LLDP block, select the desired value from the pull-down list of Active.
4. Enter the desired time (in seconds) in the Packet Interval (1~3600s) field.
5. Click SaveSet to accept the change and the phone will reboot automatically.
To configure LLDP feature via LCD interface:
1. Press Menu →Settings →Advanced Settings(The default password is "admin") →Network →LLDP.
2. Press 
and 
or press Switch soft key to select the Enable choice from the Active field.
3. Enter the desired time (in seconds) in the Packet Interval (1~3600s) field.
4. Click Save to accept the change and the phone will reboot automatically.
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After LLDP feature is enabled, the IP phone performs the following:
Periodically advertises information (e.g., hardware revision, firmware revision, serial number) of the IP phone to a multicast address on the network.
Allows LLDP packets to be received from the Internet (WAN) port.
Supports the MAC/PHY configuration (e.g., speed rate, duplex mode).
Obtains VLAN info from the network policy , this takes precedence over manual settings.
The following figure shows the LLDP packets sent and received by the IP phone, each packet contains multiple TLVs.
DHCP VLAN
IP phones support VLAN discovery via DHCP. When the VLAN Discovery method is set to DHCP, the IP phone will detect DHCP option for a valid VLAN ID. The predefined option 132 is used to supply the VLAN ID by default. You can customize the DHCP option used to detect the VLAN ID. Besides, you can use the DHCP option 133 to get the 802.1p priority of VLAN.
In addition, we also support configure multiple configurations with only one option. Option 43 is a comprehensive configuration item. You can put option 132, option 133 and so on into it. The IP Phone will get the information you configured from option 43. The specific configuration method will be described in detail later.
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To configure DHCP option 132 on a Tftpd32:
Start the Tftpd32 application.
Select the Current Directory and Server interfaces.
Click the DHCP server Tab.
Click the "Settings" button.
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Select the DHCP Server
Select the
DHCP Tab andDHCP Tab and configure the options.
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Click the "OK" button .
Open the DHCP VLAN on the Htek IP Phones
DHCP VLAN is "Disable" on IP phones by default. You can open DHCP VLAN via web interface or LCD interface. The DHCP option is 132.
To configure DHCP VLAN feature via web interface:
1. Log into the web interface.
The default username and password are both "admin".
2. Click on Network->Advanced.
3. In the DHCP VLAN field, select the desired value from the pull-down list.
4 4. Click the "SaveSet" button and a window pops up.
5. Click OK to reboot the phone.
To configure DHCP VLAN feature via LCD interface:
1. Press Menu →Settings →Advanced Settings(The default password is "admin") →Network →DHCP Vlan.
2. Press and or press Switch soft key to select the Enable choice from the DHCP Vlan field.
3 3. Click the "Save" button and then reboot the phone manually.
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When the IP phone is configured to use DHCP for VLAN discovery, and the DHCP option is set to 132, the following processes occur:
1. The IP phone broadcasts a DHCP Discover message to find out if there is a DHCP server available.
2. If the DHCP server sends a DHCP Offer message with the Option 132, the phone will accept the Offer, send a DHCP Request, and save the VLAN ID provided by the DHCP server in the DHCP option 132.
3. After the DHCP server has sent the ACK message to the phone, the phone will
release the leased IP address and start a new DHCP Discover cycle using the now
known Voice VLAN ID tag.
After this process, the phone will send all packets with the VLAN ID learned from the DHCP server in the DHCP option 132.
The following figure shows the DHCP messages sent and received by the IP phone:
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When using Bridge Mode, PC Port VID is supported. When your PC is connected to LAN Port, data (from your PC to switch) will be tagged with " PC Port VID ".
Network-->PC Port (PC Port is LAN)
Network-->Advanced
Then VOIP (SIP RTP) packets send out from device will be tagged with VLAN id 66, Data packets which send from your PC to switch will be tagged with VLAN id 18.
IP Phone
PC InternetSWTICH
VoIP VID 66Data VID 18 
Or PC Port VID is 0 (UNTAG VLAN ID), then VOIP (SIP RTP) packets send out from device will be tagged with VLAN id 66, Data packets which send from your PC to switch will UNTAG VLAN ID.
IP Phone
PC InternetSWTICH
VoIP VID 66Data NO VID
VLAN under NAT Mode
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