Separating Voice and Data Traffic Using VLANs
Switch based LLDP-MED or MAC OUI identification is the preferred method to set a phone into a specific VLAN.
On bootup, the switch can identify the device is a phone using LLDP-MED and can place the device into the correct VLAN automatically. This is sometimes referred to as a Voice VLAN in switch configurations. Every switch vendor implements this differently, but nearly all managed switches have this feature in one form or another.
Some switches will use actual LLDP-MED to identify a connected device as a phone, while some often times lower cost switches will simply use the MAC address OUI.
General Method For Configuration
- Create a new VLAN dedicated for voice traffic
- Tag new voice traffic VLAN to ports phones will connect to
- Identify the new VLAN as a "voice" or "phone" type VLAN
- Setup classification method for devices that are to be considered a phone
- Verify phone receives DHCP on voice VLAN from voice scope, and calls are able to complete.
In either case, the general setup is a default/native/untagged vlan on an interface for the data traffic, and a second tagged VLAN identified as the voice VLAN on the same interface. When the phone boots up, the switch identifies the device as a phone, and associates the phones traffic with the tagged voice VLAN.
There are other methods that require complex DHCP setups, or statically assigning the VLAN identifier into each phone individually. Neither are supported by UniVoIP.
Note
While complex double-fetch DHCP methods are not required when the network switches makes the determination as to which VLAN a device belongs, a DHCP server or Relay is still required on the voice VLAN so that phones are able to receive an IP address.
MAC Address OUI
Short for Organizational Unique Identifier, the first 24 bits of a MAC address for a network-connected device, which indicate the specific vendor for that device. The IEEE assigns OUIs to vendors. (The last 24 bits of the MAC address are the device's unique serial number, assigned to the device by the manufacturer.)
The OUI sometimes is referred to as the Vendor ID.
Vendor OUI
Mitel: 08-00-0F
Polycom: 00-04-F2
LLDP-MED
The Link Layer Discovery Protocol (LLDP) is a vendor-neutral link layer protocol used by network devices for advertising their identity, capabilities, and neighbors on an IEEE 802 local area network, principally wired Ethernet. The protocol is formally referred to by the IEEE as Station and Media Access Control Connectivity Discovery specified in IEEE 802.1AB and IEEE 802.3 section 6 clause 79.
LLDP performs functions similar to several proprietary protocols, such as Cisco Discovery Protocol (CDP), Foundry Discovery Protocol, Nortel Discovery Protocol and Link Layer Topology Discovery.
Media endpoint discovery extension
Media Endpoint Discovery is an enhancement of LLDP, known as LLDP-MED, that provides the following facilities:
- Auto-discovery of LAN policies (such as VLAN, Layer 2 Priority and Differentiated services (Diffserv) settings) enabling plug and play networking.
- Extended and automated power management of Power over Ethernet (PoE) end points.
- Inventory management, allowing network administrators to track their network devices, and determine their characteristics (manufacturer, software and hardware versions, serial or asset number).
The LLDP-MED protocol extension was formally approved and published as the standard ANSI/TIA-1057 by the Telecommunications Industry Association (TIA) in April 2006.
Below is an example of the information a switch can learn about a connected device that supports LLDP-MED.
LLDP-MED Mitel Phone Example
user@switch#show lldp neighbors detail ports ethernet 2/1/34
Local port: 2/1/34
Neighbor: 0800.0f6b.3b5a, TTL 105 seconds
+ Chassis ID (network address): 10.241.0.121
+ Port ID (MAC address): 0800.0f6b.3b5a
+ Time to live: 120 seconds
+ Port description : "LAN port"
+ System name : "mobDN 1152,MITEL 5360 IP"
+ System description : "mobDN 1152,MITEL 5360 IP,h/w rev 0,ASIC rev 1,f/w\
Boot 06.04.01.02,f/w Main 06.05.00.11"
+ System capabilities : bridge, telephone
Enabled capabilities: bridge, telephone
+ Management address (IPv4): 10.241.0.121
+ 802.3 MAC/PHY : auto-negotiation enabled
Advertised capabilities: 10BaseT-HD, 10BaseT-FD, 100BaseTX-HD,
100BaseTX-FD, fdxPause
Operational MAU type : 1000BaseT-FD
+ MED capabilities: capabilities, networkPolicy, extendedPD
MED device type : Endpoint Class III
+ MED Network Policy
Application Type : Voice
Policy Flags : Unknown Policy, Untagged
DSCP Value : 0
+ MED Network Policy
Application Type : Voice Signaling
Policy Flags : Unknown Policy, Untagged
DSCP Value : 0
+ MED Extended Power via MDI
Power Type : PD device
Power Source : Unknown Power Source
Power Priority : High (2)
Power Value : 9.5 watts (PSE equivalent: 10680 mWatts)
+ MED Hardware revision : "PCB Version: 0"
+ MED Firmware revision : "Boot 06.04.01.02"
+ MED Software revision : "Main 06.05.00.11"
+ MED Serial number : ""
+ MED Manufacturer : "Mitel Corporation"
+ MED Model name : "MITEL 5360 IP"
+ MED Asset ID : ""