VLAN Feature on Yealink IP Phones

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Yealink Technical White Paper
Virtual Local Area Network (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. Grouping devices with a
common set of requirements regardless of their physical location can greatly simplify
network design. VLANs can address issues such as scalability, security, and network
management.
IEEE 802.1Q
IEEE 802.1Q is the networking standard that supports VLANs on an Ethernet network. The
specification defines a standard method for tagging Ethernet packets with VLAN
membership information. A VLAN-aware device is the one which understands VLAN
memberships and VLAN formats. When a packet from the IP phone enters the
VLAN-aware portion of the network, a tag is added to represent the VLAN membership
of the IP phone. Each packet must be distinguishable as being within exactly one VLAN.
A packet in the VLAN-aware portion of the network that does not contain a VLAN tag is
assumed to be flowing on the native (or default) VLAN.
802.1Q adds a 4-byte tag between the source MAC address and the Ethernet type
fields of the Ethernet frame. Two bytes are used for the tag protocol identifier (TPID), the
other two bytes for tag control information (TCI). The TCI field is further divided into PCP
(Priority Code Point), CFI (Canonical Format Indicator), and VID (VLAN ID).
Voice VLAN
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.
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Yealink Technical White Paper
Virtual Local Area Network (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.
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
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Virtual Local Area Network (VLAN)
attempts to compromise the devices. It also allows locking down access to
configuration and signaling servers to only allow access from the IP phones.
There are three ways to get VLAN ID for Internet (WAN) port, but the VLAN used is
chosen by priority of each method. The priority is: LLDP>Manual>DHCP VLAN. There is
only one way to get VLAN ID for PC port: Manual.
LLDP and Manual methods are available on all Yealink IP phones. The Manual method
for PC port is not available on Yealink W52P and VP530 IP phones. DHCP VLAN method is
available on Yealink SIP-T28P, SIP-T26P, SIP-T22P, SIP-T20P, SIP-T21P, SIP-T19P, SIP-T46G,
SIP-T42G and SIP-T41P IP phones running firmware version 71 or later, and Yealink W52P
IP DECT phones running firmware version 30 or later.
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
9 bits
0-510 octets
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Virtual Local Area Network (VLAN)
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 placing 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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Virtual Local Area Network (VLAN)
LLDP provides exceptional interoperability benefits, IP telephony troubleshooting,
automatic deployment of policies and advanced PoE (Power over Ethernet). When LLDP
feature is enabled on IP phones, the IP phones periodically advertise their own
information to the directly connected LLDP-enabled switch. The IP phones can also
receive LLDP packets from the connected switch. When the application type is ―voice‖,
IP phones decide whether to update the VLAN configurations obtained from the LLDP
packets. When the VLAN configurations on the IP phones are different from the ones
sent by the switch, the IP phones perform an update and reboot. This allows the IP
phones to be plugged into any switch, obtain their VLAN IDs, and then start
communications with the call control.
TLVs supported by IP phones are summarized in the following table:
TLV Type
TLV Name
Chassis ID
Port ID
Description
Specifies the IP address of the sending
port.
Specifies the MAC address of the IP
phone.
Specifies the life of the transmitted
Mandatory TLVs
Time To Live
information on the IP phone.
The default value is 60s.
Marks the end of the TLV sequence in
the LLDPDU. No further processing of
End of LLDPDU
TLVs after this is necessary. This is a
mandatory TLV and therefore must be
present at the end of the data stream.
Specifies the
System Name
administratively-assigned name for
the IP phone (per RFC3418).
System Description
Optional TLVs
Specifies the description of the IP
phone.
Specifies the supported and enabled
capabilities of the IP phone.
System Capabilities
The supported capabilities are Bridge,
Telephone and Router.
The enabled capabilities are Bridge
and Telephone by default.
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TLV Type
Virtual Local Area Network (VLAN)
TLV Name
Description
Specifies the description of the
Port Description
sending port.
The default value is ―WAN PORT‖.
Specifies duplex and bit rate settings
of the IP phone.
The Auto Negotiation is supported and
enabled by default.
IEEE Std 802.3
Organizationally
Specific TLV
MAC/PHY
The advertised capabilities of PMD
Configuration/Status
Auto-Negotiation are:

100BASE-TX (full duplex mode)

100BASE-TX (half duplex mode)

10BASE-T (full duplex mode)

10BASE-T (half duplex mode)
Specifies the MED device type of the IP
phone and the supported LLDP-MED
TLV type can be encapsulated in
LLDPDU.
The supported LLDP-MED TLV types
Media Capabilities
Network Policy
LLDP-MED TLVs
are:

LLDP-MED Capabilities

Network Policy

Extended Power via MDI-PD

Inventory
Specifies the port VLAN ID, application
type, L2 priority and DSCP value.
Extended
Specifies power type, source, priority
Power-via-MDI
and value.
Inventory –
Specifies the hardware revision of IP
Hardware Revision
phone.
Inventory –
Specifies the firmware revision of IP
Firmware Revision
phone.
Inventory –
Specifies the software revision of IP
Software Revision
phone.
Inventory – Serial
Specifies the serial number of IP
Number
phone.
Inventory –
Manufacturer name of IP phone.
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TLV Type
Virtual Local Area Network (VLAN)
TLV Name
Description
Manufacturer Name
Inventory – Model
Name
Specifies the model name of IP phone.
Specifies the asset identifier of IP
Asset ID
phone.
The default value is ―asset‖.
LLDP is enabled on IP phones by default. You can configure LLDP via web user interface
or using configuration files. You can also configure the sending frequency of LLDP packet.
The default sending frequency is 60s. The followings take configurations of a SIP-T28P IP
phone running firmware version 71 as examples.
To configure LLDP feature via web user interface:
1.
Log into the web user interface with the administrator credential.
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 Confirm to accept the change.
The web user interface prompts the warning ―Some settings you changed take
effect when you restart your machine! Do you want to reboot now?‖.
6.
Click OK to reboot the IP phone.
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Virtual Local Area Network (VLAN)
To configure LLDP feature using configuration files:
1.
Add/Edit LLDP parameters in configuration files.
The following table shows the information of parameters:
Parameter
Description
Valid Value
Default Value
Boolean
1
Enables or disables
network.lldp.e
LLDP on the IP phone.
nable
0-Disabled
1-Enabled
Sets the sending
network.lldp.p
frequency (in
acket_interval
seconds) of LLDP
Integer
(1 to 3600)
60
packets.
The following shows an example of LLDP configuration in configuration files:
network.lldp.enable = 1
network.lldp.packet_interval = 60
2.
Upload configuration files to the root directory of the provisioning server and
trigger IP phones to perform an auto provisioning for configuration update.
For more information on auto provisioning, refer to Yealink IP Phones Auto
Provisioning Guide.
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, which takes precedence over manual
settings.
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Virtual Local Area Network (VLAN)
The following figure shows the LLDP packets sent and received by the IP phone, each
packet contains multiple TLVs.
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.
Before using DHCP VLAN feature on IP phones, you must make sure that the DHCP
option on the DHCP server is configured properly. This section provides instructions on
how to configure a DHCP option for windows using DHCP Turbo.
To configure DHCP option on a DHCP server:
1.
Start the DHCP Turbo application.
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Virtual Local Area Network (VLAN)
2.
Right click Option Types, and then select New Option Type.
3.
Enter the desired option in the Tag field.
The custom options range from 128 to 254.
4.
Enter the desired name in the Name field.
5.
Select string from the pull-down list of Type.
6.
Click OK to finish setting the option properties.
7.
Click
8.
Double click Named Policies.
to accept the change.
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9.
Virtual Local Area Network (VLAN)
Right click Global, and then select New Option.
The Option Selector screen displays as below:
10. Scroll down and double click the option created above.
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Virtual Local Area Network (VLAN)
11. Fill the VLAN ID to be assigned in the input field.
Three formats of valid values: VLAN-A=VLANID, VLANID and VID=VLANID. VLAN ID
ranges from 1 to 4094.
12. Click OK to finish setting a custom option.
13. Click
to accept the change.
Then you can find the configured option under Global option.
DHCP VLAN is enabled on IP phones by default. You can configure DHCP VLAN via web
user interface or using configuration files. You can also configure the DHCP option. The
default DHCP option is 132.The followings take configurations of a SIP-T28P IP phone
running firmware version 71 as examples.
To configure DHCP VLAN feature via web user interface:
1.
Log into the web user interface with the administrator credential.
The default administrator user name and password are both ―admin‖.
2.
Click on Network->Advanced.
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3.
Virtual Local Area Network (VLAN)
In the VLAN block, select the desired value from the pull-down list of DHCP VLAN
Active.
4.
Enter the desired value in the Option field.
You can specify 5 options at most and separate options by commas. The default
value is 132.
5.
Click Confirm to accept the change.
The web user interface prompts the warning ―Some settings you changed take
effect when you restart your machine! Do you want to reboot now?‖.
6.
Click OK to reboot the IP phone.
To configure DHCP VLAN feature using configuration files:
1.
Add/Edit DHCP VLAN parameters in configuration files.
The following table shows the information of parameters:
Parameter
Description
Valid Value
Default Value
Boolean
1
Enables or disables
network.vlan.
dhcp_enable
DHCP VLAN discovery
feature on the IP phone.
0-Disabled
1-Enabled
Specifies the DHCP
option used to detect the
network.vlan.
VLAN ID.
dhcp_option
You can specify 5 options
Integer
(128 to 254)
132
at most and separate
options by commas.
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Virtual Local Area Network (VLAN)
The following shows an example of DHCP VLAN configuration in configuration files:
network.vlan.dhcp_enable = 1
network.vlan.dhcp_option = 132
2.
Upload configuration files to the root directory of the provisioning server and
trigger IP phones to perform an auto provisioning for configuration update.
For more information on auto provisioning, refer to Yealink IP Phones Auto
Provisioning Guide.
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 obtained from the
DHCP server in the DHCP option 132.
The following figure shows the DHCP messages sent and received by the IP phone:
VLAN is disabled on IP phones by default. You can configure VLAN via web user
interface or phone user interface or using configuration files. Before configuring VLAN
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Virtual Local Area Network (VLAN)
on the IP phone, you need to obtain the VLAN ID from your network administrator. When
you configure VLAN feature, the most important issue is to confirm the type of the
connected port (access, trunk, and hybrid) on the switch. This ensures that the traffics
(tagged/untagged) from the IP phones can be transmitted properly. VLAN feature could
affect the ability of the IP phones to function in the network. Contact your network
administrator for more information before configuration.
You can enable or disable VLAN, and set specific VLAN IDs and priorities for the Internet
(WAN) port and PC port respectively. The followings take configurations of a SIP-T28P IP
phone running firmware version 71 as examples.
To configure VLAN for Internet (WAN) port via web user interface:
1.
Log into the web user interface with the administrator credential.
The default administrator user name and password are both ―admin‖.
2.
Click on Network->Advanced.
3.
In the VLAN block, select the desired value from the pull-down list of WAN Port
Active.
4.
Enter the VLAN ID in the VID (1-4094) field.
5.
Select the desired value (0-7) from the pull-down list of Priority.
7 is the highest priority.
6.
Click Confirm to accept the change.
The web user interface prompts the warning ―Some settings you changed take
effect when you restart your machine! Do you want to reboot now?‖.
7.
Click OK to reboot the IP phone.
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Virtual Local Area Network (VLAN)
To configure VLAN for PC port via web user interface:
1.
Log into the web user interface with the administrator credential.
The default administrator user name and password are both ―admin‖.
2.
Click on Network->Advanced.
3.
In the VLAN block, select the desired value from the pull-down list of PC Port Active.
4.
Enter the VLAN ID in the VID (1-4094) field.
5.
Select the desired value (0-7) from the pull-down list of Priority.
7 is the highest priority.
6.
Click Confirm to accept the change.
The web user interface prompts the warning ―Some settings you changed take
effect when you restart your machine! Do you want to reboot now?‖.
7.
Click OK to reboot the IP phone.
To configure VLAN for Internet (WAN) port via phone user interface:
1.
Press Menu->Settings->Advanced Settings (password: admin)
->Network->VLAN->WAN Port.
2.
Press
or
, or the Switch soft key to select the desired value from VLAN
Status field.
3.
Enter the VLAN ID (1-4094) in the VID Number field.
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4.
Virtual Local Area Network (VLAN)
Enter the desired value (0 to 7) in the Priority field.
7 is the highest priority.
5.
Press the Save soft key to accept the change.
The IP phone reboots automatically to make settings effective after a period of
time.
To configure VLAN for PC port via phone user interface:
1.
Press Menu->Settings->Advanced Settings (password: admin)
->Network->VLAN->PC Port.
2.
Press
or
, or the Switch soft key to select the desired value from VLAN
Status field.
3.
Enter the VLAN ID (1-4094) in the VID Number field.
4.
Enter the desired value (0 to 7) in the Priority field.
7 is the highest priority.
5.
Press the Save soft key to accept the change.
The IP phone reboots automatically to make settings effective after a period of
time.
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Virtual Local Area Network (VLAN)
To configure VLAN for Internet (WAN) port and PC port using configuration file:
1.
Add/Edit VLAN for Internet (WAN) port and PC port parameters in configuration
files.
The following table shows the information of parameters:
Parameter
Description
Valid Value
Default Value
Boolean
0
Enables or disables the IP
network.vlan.
internet_port_
enable
phone to tag VLAN ID in
packets sent from the
Internet (WAN) port.
0-Disabled
1-Enabled
network.vlan.
Configures the VLAN ID
internet_port_
that associates with the
vid
particular VLAN.
network.vlan.
Specifies the priority used
internet_port_
for transmitting VLAN
priority
packets.
Integer
(1 to 4094)
Integer
(0 to 7)
1
0
Enables or disables the IP
network.vlan.
pc_port_ena
ble
phone to tag VLAN ID in
packets sent from the PC
port.
Boolean
0
0-Disabled
1-Enabled
network.vlan.
pc_port_vid
Configures the VLAN ID
that associates with the
particular VLAN.
network.vlan.
Specifies the priority used
pc_port_priori
for transmitting VLAN
ty
packets.
Integer
(1 to 4094)
Integer
(0 to 7)
1
0
The following shows an example of VLAN configuration in configuration files:
network.vlan.internet_port_enable = 1
network.vlan.internet_port_vid = 77
network.vlan.internet_port_priority = 2
network.vlan.pc_port_enable = 1
network.vlan.pc_port_vid = 76
network.vlan.pc_port_priority = 3
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2.
Virtual Local Area Network (VLAN)
Upload configuration files to the root directory of the provisioning server and
trigger IP phones to perform an auto provisioning for configuration update.
For more information on auto provisioning, refer to Yealink IP Phones Auto
Provisioning Guide.
The IP phone reboots after VLAN feature has been enabled. After starting up, the IP
phone will be assigned with a subnet address defined for VLAN 77.
The following figure shows the VLAN ID sent and received by the IP phone:
IEEE (Institute of Electrical and Electronics Engineers) –a professional association
headquartered in New York City that is dedicated to advancing technological
innovation and excellence.
TIA (Telecommunications Industry Association) –accredited by the American National
Standards Institute (ANSI) to develop voluntary, consensus-based industry standards
for a wide variety of ICT products.
IEEE 802.3 –a working group and a collection of IEEE standards produced by the
working group defining the physical layer and data link layer's media access control
(MAC) of wired Ethernet.
Port-based VLAN –a port-based VLAN is a group of ports on a Gigabit Ethernet Switch
that form a logical Ethernet segment. Each port of a port-based VLAN can belong to
only one VLAN at a time.
Port and Protocol-based VLAN –initially defined in IEEE 802.1v (currently amended as
part of 802.1Q-2003) enables data frame classification and assignment to unique VLANs
based on the received data frame type and the protocol information in its payload.
TPID (tag protocol identifier) –a 16-bit field set to a value of 0x8100 in order to identify
the frame as an IEEE 802.1Q-tagged frame. It is used to distinguish the frame from
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Virtual Local Area Network (VLAN)
untagged frames.
PCP (Priority Code Point) –a 3-bit field which refers to the IEEE 802.1p priority. It indicates
the frame priority level. Values are from 0 (best effort) to 7 (highest); 1 represents the
lowest priority.
CFI (Canonical Format Indicator) –used for compatibility reason between Ethernet type
network and Token Ring type network. It is always set to zero for Ethernet switches. If a
frame received at an Ethernet port has a CFI set to 1, then that frame should not be
forwarded as it is to an untagged port.
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Virtual Local Area Network (VLAN)
LLDP and LLDP-MED: http://en.wikipedia.org/wiki/Link_Layer_Discovery_Protocol
IEEE 802.3: http://www.ieee802.org/3/
VLAN: http://en.wikipedia.org/wiki/Virtual_LAN
IEEE 802.1q: http://en.wikipedia.org/wiki/802.1Q
LLDP on Cisco Switch:
http://www.cisco.com/en/US/docs/switches/lan/catalyst3750/software/release/12.2_55_s
e/configuration/guide/swlldp.html
We are striving to improve our documentation quality and we appreciate your feedback. Email
your opinions and comments to DocsFeedback@yealink.com.
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