P3P: Platform for Privacy Preferences
The Platform for Privacy Preferences (P3P) is a protocol allowing Websites to declare their intended use of information they collect about browsing users. Designed to give users more control of their personal information when browsing, P3P was developed by the World Wide Web Consortium (W3C) and officially recommended on April 16, 2002.
Standard Organization: W3C
PAgP: Port Aggregation Protocol
Port Aggregation Protocol (PAgP) aids in the automatic creation of Fast EtherChannel links. PAgP packets are sent between Fast EtherChannel-capable ports in order to negotiate the forming of a channel.
Standard Organization: Cisco
PAP: Password Authentication Protocol
The Password Authentication Protocol (PAP), a Link Control Protocol in the PPP suite, provides a simple method for the peer to establish its identity using a 2-way handshake. This is done only upon initial link establishment. Unlike CHAP, PAP passes the password and the host name or username in the clear (unencrypted). PAP does not itself prevent unauthorized access but merely identifies the remote end. The router or access server then determines whether that user is allowed access.
Standard Organization: IETF
Reference Document: RFC 1994
PAP: Printer Access Protocol
Printer Access Protocol (PAP), a protocol in the AppleTalk suite, manages the virtual connection to printers and other servers in an AppleTalk network.
Standard Organization: Apple
PDCP: Packet Data Convergence Protocol
Packet Data Convergence Protocol (PDCP) is used in UMTS 3G network to map higher-level protocol characteristics onto the characteristics of the underlying radio-interface protocols, providing protocol transparency for higher-layer protocols. PDCP also provides protocol control information compression.
Standard Organization: 3GPP
Reference Document: 3GPP TS 25.323
PEAP: Protected Extensible Authentication Protocol
Protected Extensible Authentication Protocol(PEAP), a protocol developed by Microsoft, Cisco and RSA Security as an open standard, is used to authenticate wireless LAN clients without requiring them to have certificates. PEAP is a method to securely transmit authentication information, including passwords, over wireless networks. PEAP utilizes Transport Layer Security (TLS) to set up an end-to-end tunnel to transfer the user's credentials without having to use a certificate on the client. PEAP uses only server-side public key certificates to authenticate clients by creating an encrypted SSL/TLS tunnel between the client and the authentication server, which protects the ensuing exchange of authentication information from casual inspection.
Reference Document: IETF Draft
PEP: Packet Exchange Protocol
Packet Exchange Protocol(PEP), an Xerox protocol, provides a semi-reliable packet delivery service that orients towards single-packet exchanges.
Standard Organization: Xerox
PGM: Pragmatic General Multicast
Pragmatic General Multicast (PGM) is a reliable transport protocol for applications that require ordered or unordered, duplicate-free, multicast data delivery from multiple sources to multiple receivers.PGM is specifically intended as a workable solution for multicast applications with basic reliability requirements rather than as a comprehensive solution for multicast applications with sophisticated ordering, agreement and robustness requirements. Its central design goal is simplicity of operation with due regard for scalability and network efficiency.
Standard Organization: IETF
Reference Document: RFC 3208
PIC: Pre-IKE Credential Provisioning Protocol
Pre-IKE Credential (PIC) Provisioning Protocol is a proposed replacement for the Internet Key Exchange (IKE) protocol. PIC presents a method to bootstrap IPSec authentication via an "Authentication Server" (AS) and legacy user authentication (e.g., RADIUS). The client machine communicates with the AS using a key exchange protocol where only the server is authenticated, and the derived keys are used to protect the legacy user authentication. Once the user is authenticated, the client machine obtains credentials from the AS that can be later used to authenticate the client in a standard IKE exchange with an IPSec-enabled security gateway. The later stage does not require user intervention. The proposed server-authenticated key exchange uses an ISAKMP-based protocol, similar to a simplified IKE exchange, and arbitrary legacy authentication is supported via the use of the EAP protocol.
Standard Organization: IETF
PIM: Protocol Independent Multicast
Protocol Independent Multicast (PIM) refers to a group of multicast routing protocols, each optimized for a different environment. There are two main PIM protocols, PIM Sparse Mode and PIM Dense Mode. A third PIM protocol, Bi-directional PIM(BIDIR-PIM), is less widely used. All PIM protocols share a common control message format. PIM control messages are sent as raw IP datagrams, either multicast to the link-local ALL PIM ROUTERS multicast group, or unicast to a specific destination.
Standard Organization: IETF
Reference Document: RFC 2362
PIM-DM: PIM Dense Mode
PIM Dense Mode (PIM-DM), one of Protocol Independent Multicast protocols, is mainly designed for multicast LAN applications, while the PIM-SM is for wide area, inter-domain networks. PIM-DM implements the same flood-and-prune mechanism that Distance Vector Multicast Routing Protocol (DVMRP) and other dense mode routing protocols employ. The main difference between DVMRP and PIM-DM is that PIM-DM introduces the concept of protocol independence. PIM-DM can use the routing table populated by any underlying unicast routing protocol to perform reverse path forwarding (RPF) checks.
Standard Organization: IETF
Reference Document: RFC 3973
PIM-SM: PIM Sparse Mode
PIM Sparse Mode (PIM-SM), one of Protocol Independent Multicast protocols, is for efficiently routing to multicast groups that may span wide-area (WAN and inter-domain) internets, while PIM-DM is mainly for LAN. The protocol is not dependent on any particular unicast routing protocol and is designed to support sparse groups. It uses the traditional IP multicast model of receiver-initiated membership, supports both shared and shortest-path trees and uses soft-state mechanisms to adapt to changing network conditions. It can use the route information that any routing protocol enters into the multicast Routing Information Base (RIB).
Standard Organization: IETF
Reference Document: RFC 2362
PMAP: Port Mapper
The Port Mapper (PMAP) protocol manages the allocation of transport layer ports to network server applications, which eliminates the need to reserve permanently a port number for each application because only the PMAP application itself requires a reserved port. Server applications obtain a port by requesting a port assignment using PMAP. Clients wanting to access an application first call the PMAP program through a well-known port to obtain the transport port registered to the application. The client then calls the application directly using the registered port.
Standard Organization: Sun
PLP: Packet Level Protocol
Packet Level Protocol (PLP), also known as X.25 Level 3 protocol, is a network layer protocol in the X.25 protocol stack.
Standard Organization: ITU-T
PNG: Portable Network Graphics
Portable Network Graphics (PNG) is an extensible file format for the lossless, portable, well-compressed storage of raster images. PNG provides a patent-free replacement for GIF and can also replace many common uses of TIFF. Indexed-color, grayscale, and truecolor images are supported, plus an optional alpha channel. Sample depths range from 1 to 16 bits. PNG is designed to work well in online viewing applications, such as the World Wide Web, so it is fully streamable with a progressive display option. PNG is robust, providing both full file integrity checking and simple detection of common transmission errors. Also, PNG can store gamma and chromaticity data for improved color matching on heterogeneous platforms.
Standard Organization: IETF
Reference Document: RFC 2083
PNNI: ATM Private Network-Node Interface
Private Network-Node Interface (PNNI), a critical ATM network-to-network signaling protocol, provides mechanisms to support scalable, QoS-based ATM routing and switch-to-switch switched virtual connection (SVC) interoperability. The PNNI is a hierarchical, dynamic link-state routing protocol. It is designed to support large-scale ATM networks. PNNI is based on UNI 4.0 and Q.2931.
Standard Organization: ITU-T
POP: Post Office Protocol
The Post Office Protocol(POP) is designed to allow a workstation with an email client to dynamically access a mail drop on a server host over the TCP/IP network. POP3 is the version 3 (the latest version) of the Post Office Protocol, which has obsoleted the earlier versions of the POP protocol: POP1 and POP2. POPs are not intended to provide extensive manipulation operations of mail on the server; normally, mail is downloaded and then deleted.
Standard Organization: IETF
Reference Document: RFC 1939
POP1: Post Office Protocol version 1
The Post Office Protocol version 1 (POP1) is designed to allow a workstation with an email client to dynamically access a mail drop on a server host over the TCP/IP network. POP1 has been obsoleted by the latest version POP3.
Standard Organization: IETF
Reference Document: RFC 918
POP2: Post Office Protocol version 2
The Post Office Protocol version 2 (POP2) is designed to allow a workstation with an email client to dynamically access a mail drop on a server host over the TCP/IP network. POP2 has been obsoleted by the latest version POP3.
Standard Organization: IETF
Reference Document: RFC 937
POP3: Post Office Protocol version 3
The Post Office Protocol version 3 (POP3) is designed to allow a workstation with an email client to dynamically access a mail drop on a server host. POP3 is the version 3 (the latest version) of the Post Office Protocol. POP3 transmissions appear as data messages between stations. The messages are either command or reply messages. POP3 is not intended to provide extensive manipulation operations of mail on the server; normally, mail is downloaded and then deleted.
Standard Organization: IETF
Reference Document: RFC 1939
Port Mapper
The Port Mapper (PMAP) protocol manages the allocation of transport layer ports to network server applications, which eliminates the need to reserve permanently a port number for each application because only the PMAP application itself requires a reserved port. Server applications obtain a port by requesting a port assignment using PMAP. Clients wanting to access an application first call the PMAP program through a well-known port to obtain the transport port registered to the application. The client then calls the application directly using the registered port.
Standard Organization: Sun
Port Number
Port numbers are associated with TCP and UDP protocols designed to distinguish multiple applications running on a single device with one IP address from one another. Since many network applications may be running on the same machine, computers need something to make sure the correct software application on the destination computer gets the data packets from the source machine, and to make sure replies get routed to the correct application on the source computer. This is accomplished through the use of the TCP or UDP "port numbers". In the TCP and UDP header, there are "SourcePort" and "DestinationPort" fields which are used to indicate the message sending process and receiving process identities defined. The combination of the IP address and the port number is called "socket".
Standard Organization: IANA
PoS: Packet over SONET/SDH
Packet Over SONET/SDH (PoS) is a technology that maps IP datagrams into the SONET frame payload using Point-to-Point Protocol (PPP). Packet over SONET (PoS) is a highly scalable protocol that overcomes many of the inefficiencies of ATM, while providing legacy support to internetworks with existing SONET architectures. PoS provides a mechanism to carry packets directly within the SONET synchronous payload envelope (SPE) using a small amount of High-Level Data Link Control (HDLC) or PPP framing. PoS has three layers:
Top layer: IP encapsulation into PPP
Mid layer: Framing of PPP with HDLC
Bottom layer: Mapping into SONET
Standard Organization: IETF
Reference Document: RFC 2615
PP: ISO Presentation Protocol
The ISO Presentation Protocol (PP), also known as ISO-PP, is for information transit between open systems using connection-oriented or connectionless mode transmission at the presentation layer of the OSI 7 layer model. An application protocol is specified in terms of the transfer of presentation data values between application entities (PS users), using the User data parameter of presentation service primitives.
Standard Organization: ISO
PPP Multilink Protocol
The PPP Multilink protocol, also known as Multilink PPP (Multilink PPP, MultiPPP or MP), is a method for splitting, recombining and sequencing datagrams across multiple logical data links. This work was originally motivated by the desire to exploit multiple bearer channels in ISDN, but is equally applicable to any situation in which multiple PPP links connect two systems, including async links. PPP MultiLink protocol is based on an LCP option negotiation that permits a system to indicate to its peer that it is capable of combining multiple physical links into a "bundle".
Standard Organization: IETF
Reference Document: RFC 1990
PPP NCP: Network Control Protocol in PPP
The Network Control Protocol (NCP), a protocol in the Point-to-Point Protocol (PPP) suite, provides services in the PPP link connection process to establish and configure different network-layer protocols such as IP, IPX or AppleTalk. After an NCP has reached the opened state, PPP will carry the corresponding network-layer protocol packets. Any supported network-layer protocol packets received when the corresponding NCP is not in the opened state must be silently discarded. The most commonly used NCPs are IP Control Protocol (IPCP) and IPv6CP.
Standard Organization: IETF
Reference Document: RFC 1661
PPP: Point-to-Point Protocol
The Point-to-Point Protocol (PPP) suite provides a standard method for transporting multi-protocol datagrams over point-to-point links. PPP was originally devised as an encapsulation protocol for transporting IP traffic between two peers. It is a data link layer protocol (layer 2 in the OSI model) in the TCP-IP protocol suite for synchronous modem links, as a replacement for the non-standard layer 2 protocol, SLIP. However, other protocols other than IP can also be carried over PPP, including DECnet and Novell's Internetwork Packet Exchange (IPX).
Standard Organization: IETF
Reference Document: RFC 1661
PPP-BPDU: PPP Bridge Protocol Data Unit
Bridge Protocol Data Unit (BPDU), a protocol in the PPP suite, is some "hello packets" of the spanning tree protocol sent out at intervals to exchange information among bridges in the network. BPDUs help describe and identify attributes of a switch port and allow for switches to obtain information about each other.
Standard Organization: IETF
PPPoA: PPP over ATM AAL5
PPP over ATM AAL5 (PPPoA) describes the use of ATM Adaptation Layer 5 (AAL5) for framing PPP encapsulated packets.The Point-to-Point Protocol (PPP) provides a standard method for transporting multi-protocol datagrams over point-to-point links.
Standard Organization: IETF
Reference Document: RFC 2364
PPPoE: PPP over Ethernet
PPP over Ethernet (PPPoE) provides the ability to connect a network of hosts over a simple bridging access device to a remote Access Concentrator. With this model, each host utilizes its own PPP stack and the user is presented with a familiar user interface. Access control, billing and type of service can be done on a per-user, rather than per-site, basis.
Standard Organization: IETF
Reference Document: RFC 2516
PPTP: Point-to-Point Tunneling Protocol
Point-to-Point Tunneling Protocol (PPTP), defined originally by Microsoft, is a protocol that allows corporations to extend their corporate network through private "tunnels" over the public Internet, which is known as a virtual private network (VPN). VPN enables a company not to lease private lines but to use the public networks for wide-area communication securely. PPTP is replaced by an IETF standard called Layer 2 Tunneling Protocol (L2TP).
Standard Organization: Microsoft
PVST: Per-VLAN Spanning Tree
Per-VLAN Spanning Tree (PVST) maintains a spanning tree instance for each VLAN configured in the network. It uses ISL Trunking and allows a VLAN trunk to be forwarding for some VLANs while blocking for other VLANs. Since PVST treats each VLAN as a separate network, it has the ability to load balance traffic (at layer-2) by forwarding some VLANs on one trunk and other VLANs on another trunk without causing a Spanning Tree loop.
Standard Organization: Cisco
PVST+: Per-VLAN Spanning Tree Plus
Per VLAN Spanning Tree Plus (PVST+), an enhancement to the 802.1Q specification and unsupported on non-Cisco devices, maintains a spanning tree instance for each VLAN configured in the network. PVST+ is a new version of PVST, uses ISL Trunking and allows a VLAN trunk to be forwarding for some VLANs while blocking for other VLANs. Since PVST treats each VLAN as a separate network, it has the ability to load balance traffic (at layer-2) by forwarding some VLANs on one trunk and other Vlans on another trunk without causing a Spanning Tree loop.
Standard Organization: Cisco
PUP: PARC Universal Protocol
PARC Universal Protocol (PUP), also known as PARC Universal Packet, developed at Xerox PARC, is an early internetworking protocol suite for network routing and packet delivery. In the 1980s Xerox used PUP as the base for the Xerox Network Services (XNS) protocol suite; some of the protocols in the XNS suite (e.g. the Internetwork Datagram Protocol) were lightly modified versions of the ones in the PUP suite, but others are quite different, reflecting the experience gained with PUP.