Specifications

Network Configuration Concepts
211
• Use VLAN 1 to 999 with Cisco products. VLANS can be extended from 1000 upwards. Care
in selection should be exercised in this case as some VLANs are already reserved for other
network usage.
• Set Priority for untagged VLAN/native VLAN/default_vlan to 0.
• Hubs don’t support priority queuing, so use managed Layer 2 switches with 802.1p/Q
support.
• Do not use VLAN 4095 with HP products; this is reserved for inter-switch use.
• Do not use VLAN 4094 with the CXi controller.
Cisco port examples
The following data is collected from the command line interface (RS232 connection).
• Dual mode/trunk (Legacy operation of phones with attached PC)
- This mode allows untagged information to be placed onto a specific VLAN as well as
passing VLAN tagged data for other VLAN. This configuration is used to connect to a
dual-port phone with an attached PC (no VLAN). This setting would be used when the
phone only supports DHCP LAN parameters, i.e. it cannot be programmed statically,
it does not support LLDP-MED, it is not CDP compatible AND it has an attached PC,
otherwise use the Access port method.
>switchport trunk encapsulation dot1q
>switchport trunk native vlan 193
>switchport mode trunk
>spanning-tree portfast
- This configuration is for the dual-port phones. The port provides VLAN tagging through
the first command line, and the encapsulation type is set to IEEE 802.1Q (dot1q).
Cisco also supports a similar scheme of priority with ISL encapsulation, but this is
proprietary and does not operate with other vendor equipment.
- The port is configured so that untagged information is directed to (native) VLAN 193.
- The port is considered a trunk because it handles multiple VLAN connections.
- The last command indicates that this port is not closed down during spanning tree
operations.The network engineer must ensure that there are no network loops behind
this connection. This command is used when connecting to a server or to the main
controller. This setting may change depending on E911 emergency requirements.
- Issues may also arise with switches that link MAC addresses and access security,
such as “sticky MAC” where the phone could exist on multiple (2) VLANs. Initial setup
may work, but subsequent restarts may be blocked.
• Access port/non-VLAN-aware device/IP Phone operation on the voice VLAN
- This port can have multiple functions and may be used to directly connect servers or
voice applications, such as a 3300ICP or a voice mail server. In this case only a single
device is connected to the network port. The Native VLAN will be configured to the
voice VLAN.
- The other use for this port is at the user connection where the IP Phone and possibly
also a PC connection off the phone exists. The Native VLAN will be configured to the
data VLAN for the PC, the same as if the phone were not on the connection. The Voice
VLAN will specify the voice VLAN for the switch and the phone will send tagged