Supported Network Protocols
Cisco IP Conference Phones support several industry-standard and Cisco network protocols that are required for voice communication. The following table provides an overview of the network protocols that the phones support.
Network Protocol |
Purpose |
Usage Notes |
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Bootstrap Protocol (BootP) |
BootP enables a network device, such as the phone, to discover certain startup information, such as its IP address. |
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Cisco Discovery Protocol (CDP) |
CDP is a device-discovery protocol that runs on all Cisco-manufactured equipment. A device can use CDP to advertise its existence to other devices and receive information about other devices in the network. |
The phone uses CDP to communicate information such as auxiliary VLAN ID, per port power management details, and Quality of Service (QoS) configuration information with the Cisco Catalyst switch. |
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Dynamic Host Configuration Protocol (DHCP) |
DHCP dynamically allocates and assigns an IP address to network devices. DHCP enables you to connect an IP phone into the network and have the phone become operational without the need to manually assign an IP address or to configure extra network parameters. |
DHCP is enabled by default. If disabled, you must manually configure the IP address, subnet mask, gateway, and a TFTP server on each phone locally. We recommend that you use DHCP custom option 150. With this method, you configure the TFTP server IP address as the option value.
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Hypertext Transfer Protocol (HTTP) |
HTTP is the standard protocol for transfer of information and movement of documents across the Internet and the web. |
Phones use HTTP for XML services, provisioning, upgrade and for troubleshooting purposes. |
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Hypertext Transfer Protocol Secure (HTTPS) |
Hypertext Transfer Protocol Secure (HTTPS) is a combination of the Hypertext Transfer Protocol with the SSL/TLS protocol to provide encryption and secure identification of servers. |
Web applications with both HTTP and HTTPS support have two URLs configured. phones that support HTTPS choose the HTTPS URL. A lock icon is displayed to the user if the connection to the service is via HTTPS. |
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IEEE 802.1X |
The IEEE 802.1X standard defines a client-server-based access control and authentication protocol that restricts unauthorized clients from connection to a LAN through publicly accessible ports. Until the client is authenticated, 802.1X access control allows only Extensible Authentication Protocol over LAN (EAPOL) traffic through the port to which the client is connected. After authentication is successful, normal traffic can pass through the port. |
The phone implements the IEEE 802.1X standard through support for the following authentication methods: EAP-FAST and EAP-TLS. When 802.1X authentication is enabled on the phone, you should disable the voice VLAN. |
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Internet Protocol (IP) |
IP is a messaging protocol that addresses and sends packets across the network. |
To communicate with IP, network devices must have an assigned IP address, subnet, and gateway. IP addresses, subnets, and gateways identifications are automatically assigned if you are using the phone with Dynamic Host Configuration Protocol (DHCP). If you are not using DHCP, you must manually assign these properties to each phone locally. The phones support IPv6 address. |
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Link Layer Discovery Protocol (LLDP) |
LLDP is a standardized network discovery protocol (similar to CDP) that is supported on some Cisco and third-party devices. |
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Link Layer Discovery Protocol-Media Endpoint Devices (LLDP-MED) |
LLDP-MED is an extension of the LLDP standard developed for voice products. |
The phone supports LLDP-MED on the SW port to communicate information such as:
For more information about LLDP-MED support, see the LLDP-MED and Cisco Discovery Protocol white paper at this URL: http://www.cisco.com/en/US/tech/tk652/tk701/technologies_white_paper0900aecd804cd46d.shtml |
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Real-Time Transport Protocol (RTP) |
RTP is a standard protocol for transporting real-time data, such as interactive voice and video, over data networks. |
Phones use the RTP protocol to send and receive real-time voice traffic from other phones and gateways. |
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Real-Time Control Protocol (RTCP) |
RTCP works in conjunction with RTP to provide QoS data (such as jitter, latency, and round trip delay) on RTP streams. |
RTCP is enabled by default. |
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Session Initiation Protocol (SIP) |
SIP is the Internet Engineering Task Force (IETF) standard for multimedia conferencing over IP. SIP is an ASCII-based application-layer control protocol (defined in RFC 3261) that can be used to establish, maintain, and terminate calls between two or more endpoints. |
Like other VoIP protocols, SIP is designed to address the functions of signaling and session management within a packet telephony network. Signaling allows call information to be carried across network boundaries. Session management provides the ability to control the attributes of an end-to-end call. Cisco IP Phones support the SIP protocol when the phones operate in IPv6-only, IPv4-only, and in both IPv4 and IPv6. |
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Secure Real-Time Transfer protocol (SRTP) |
SRTP is an extension of the Real-Time Protocol (RTP) Audio/Video Profile and ensures the integrity of RTP and Real-Time Control Protocol (RTCP) packets providing authentication, integrity, and encryption of media packets between two endpoints. |
Phones use SRTP for media encryption. |
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Transmission Control Protocol (TCP) |
TCP is a connection-oriented transport protocol. |
Phones use TCP to connect to a third-party call server and to access XML services. |
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Transport Layer Security (TLS) |
TLS is a standard protocol for securing and authenticating communications. |
When security is implemented, phones use the TLS protocol when securely registering with the third-part call server. |
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Trivial File Transfer Protocol (TFTP) |
TFTP allows you to transfer files over the network. On the phone, TFTP enables you to obtain a configuration file specific to the phone type. |
TFTP requires a TFTP server in your network, which can be automatically identified from the DHCP server. If you want a phone to use a TFTP server other than the one specified by the DHCP server, you must manually assign the IP address of the TFTP server by using the Network Setup menu on the phone. |
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User Datagram Protocol (UDP) |
UDP is a connectionless messaging protocol for delivery of data packets. |
Phones transmit and receive RTP streams, which utilize UDP. |