Vlan Interaction; External Devices - Cisco 8800 Series Manual

Technical Details
Network protocol
Trivial File Transfer Protocol (TFTP)
User Datagram Protocol (UDP)

VLAN Interaction

The Cisco IP Phone contains an internal Ethernet switch, enabling forwarding of packets to the phone, and
to the computer (access) port and the network port on the back of the phone.
If a computer is connected to the computer (access) port, the computer and the phone share the same physical
link to the switch and share the same port on the switch. This shared physical link has the following implications
for the VLAN configuration on the network:
• The current VLANs might be configured on an IP subnet basis. However, additional IP addresses might
• Data traffic present on the VLAN supporting phones might reduce the quality of VoIP traffic.
• Network security may indicate a need to isolate the VLAN voice traffic from the VLAN data traffic.
You can resolve these issues by isolating the voice traffic onto a separate VLAN. The switch port to which
the phone connects would be configured for separate VLANs for carrying:
• Voice traffic to and from the IP phone (auxiliary VLAN on the Cisco Catalyst 6000 series, for example)
• Data traffic to and from the PC that connects to the switch through the computer (access) port of the IP
Isolating the phones on a separate, auxiliary VLAN increases the quality of the voice traffic and allows a large
number of phones to be added to an existing network that does not have enough IP addresses for each phone.
For more information, see the documentation that is included with a Cisco switch. You can also access switch
information at this URL:
http://cisco.com/en/US/products/hw/switches/index.html

External Devices

We recommend that you use good-quality external devices that are shielded against unwanted radio frequency
(RF) and audio frequency (AF) signals. External devices include headsets, cables, and connectors.
Purpose
TFTP allows you to transfer files over the
network.
On the Cisco IP Phone, TFTP enables you
to obtain a configuration file specific to the
phone type.
UDP is a connectionless messaging
protocol for delivery of data packets.
not be available to assign the phone to the same subnet as other devices that connect to the same port.
phone (native VLAN)
Cisco IP Phone 8800 Series Multiplatform Phone Administration Guide for Release 11.3(1) and Later
VLAN Interaction
Usage notes
TFTP requires a TFTP server in your
network that the DHCP server can
automatically identify.
UDP is used only for RTP streams. SIP
signaling on the phones do not support
UDP.
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