PAN (Personal Area Network)    

See Bluetooth;  Wireless PANs (Personal Area Networks).           

PAP (Password Authentication Protocol)

PAP is an authentication protocol that requires users to enter a password before accessing a secure system. The user’s name and password are sent over the wire to a server, where they are  compared with a database of user account names and passwords. This technique is vulnerable to wiretapping (sniffing) because the password can be captured and used by someone to log on to the system.

PBX (Private Branch Exchange)

A PBX is a telephone switch located on the premises of a company. It allows telephone users to set up circuit-switched voice calls among other users in the same company or to set up calls across the public-switched telephone network. People calling into the company dial a single number. The PBX routes the call to the appropriate extension. Internal users have a number of outgoing lines for making calls over the public network. By connecting internal users with other internal users, the PBX avoids the need for an internal call to be set up across the telephone company’s switch.     

Peer-to-Peer Communication 

This topic discusses various forms of peer-to-peer communications, including peer communications in the OSI protocol stack, traditional peer-to-peer networking (as compared to client/ server networking), and community-based P2P (peer-to-peer) networking techniques made famous by Napster.

PIM (Protocol Independent Multicast)

See Multicasting.

Ping (Packet Internet Groper)

Ping is a utility associated with UNIX, the Internet, and TCP/IP networks.

Since most network operating systems now support TCP/IP, they also include a Ping utility. Ping is the equivalent to yelling in a canyon and listening for the echo. Ping uses ICMP (Internet Control Message Protocol) for its operation. Specifically, it sends an ICMP echo request message to the designated host. If the device is reachable before atime-out period, your host will receive an ICMP echo reply message. Ping can be used as a troubleshooting tool when communication problems occur.

PIM-DM 

 Internet Protocol (IP) multicast is a bandwidth-conserving technology that reduces traffic by simultaneously delivering a single stream of information to thousands of corporate recipients and homes. Applications that take advantage of multicast include videoconferencing, corporate communications, distance learning, and distribution of software, stock quotes, and news.PIM, or Protocol Independent Multicast, is a multicasting routing protocol that runs over an existing unicast infrastructure. There are two modes of PIM, PIM-DM (Dense Mode) and PIM-SM (Sparse Mode). PIM Dense Mode (PIM-DM). is used when the targeted recipients are in a concentrated area.An example of this might be a company presentation by the CEO or President of a company. By way of contrast, PIM Sparse Mode (PIM-SM) assumes relatively fewer receivers. An example would be the initial orientation video for new employees.

PIM-SM

Protocol Independent Multicast-Sparse Mode (PIM-SM) routes multicast packets to multicast groups, across wide area networks (WANs).PIM-SM is called “protocol independent” because it can use the route information that any routing protocol enters into the multicast Routing Information Base (RIB), or, as it is known in Windows terminology, the multicast view. Examples of these routing protocols include unicast protocols such as the Routing Information Protocol (RIP) and Open Shortest Path First (OSPF), but multicast protocols that populate the routing tables—such as the Distance Vector Multicast Routing Protocol (DVMRP)—can also be used. Sparse mode means that the protocol is designed for situations where multicast groups are thinly populated across a large region. Sparse-mode protocols can operate in LAN environments, but they are most efficient over WANs.

Ports, TCP/IP  

 Computers have a variety of physical hardware ports over which data is transmitted between input/output devices and external peripherals. A typical computer has parallel printer ports, serial ports, USB ports, a keyboard connector, and a mouse connector. Likewise, software processes running in computers need “software ports” to connect with other software processes. Inter process communication (IPC) takes place between these ports.  In the Internet Protocol suite, the TCP and UDP protocols use ports to support interprocess communications between different networked devices. A single host may have multiple

 processes running at the same time, connected to one or more computers. Each of these processes is multiplexed through the same network interface and local network link. In other words, packets from each of these processes are interleaved and sent through the network

interface. A port can be thought of as a message queue through which these packets pass.

PoE)  802.3af Power-over-Ethernet(     

802.3af is an international standard for powering network-connected devices over Ethernet, allowing users to take advantage of future third-party products such as sensors and wireless access points that don't require a conventional wall socket

Power over Ethernet technology is designed to ease the deployment of some devices connected to a LAN by eliminating the need to plug them into a conventional power socket. The 802.3af standard offers more power than Cisco's earlier technology, extending the range of devices that can be powered over the network to include IP security cameras, motion detectors and card readers. It also opens the door to more advanced color IP (Internet Protocol) phones and multiband wireless LAN access points. With 802.3af support, a networked device will be able to draw as much as 15.4 watts of power from an Ethernet port over standard copper wire used for Ethernet. This is enough for some IP phones and other wireless devices.

PPP (Point-to-Point Protocol)

Two schemes have been adopted by the Internet community to encapsulate and transmit IP (Internet Protocol) datagrams over serial point-to-point links: SLIP (Serial Line Interface Protocol) and PPP (Point-to-Point Protocol). SLIP is an earlier protocol that has fallen into disuse. PPP predominates because it works with other protocols such as IPX and was designed   to overcome problems with the earlier protocol.              

PPP provides router-to-router, host-to-router, and host-to-host connections. PPP is the protocol used to establish dial-up Internet connections between users and an Internet POP (point of presence).  

PPTP (Point-to-Point Tunneling Protocol)   

See L2TP (Layer 2 Tunneling Protocol); Modems; and VPN (Virtual Private Network).

Proxy Servers

The proxy server can be viewed as a gateway between two networks,

usually a private internal network and the Internet. It is sometimes called an application-level gateway. The proxy server  hides the internal network from the external network. It keeps hackers from accessing or even   knowing about internal IP addresses. A proxy server runs as software on a computer and acts on behalf of a client to make requests outside the client’s network.

Protocol VLAN (phase 2) )802.1v

IEEE 802.1v provides the capability to support Port-and-Protocol-based VLAN classification, including multiple VLAN ID values per port. In addition to the Port VLAN ID, for bridges that  implement Port-and-Protocol-based VLAN classification, the VLAN ID associated with an Untagged or Priority-tagged frame is determined based on the Port of arrival of the frame into the bridge and on the protocol identifier of the frame. Classifying multiple protocols into a single VLAN often imposes VLAN boundaries that are inappropriate for some of the protocols, requiring the presence of a non-standard entity to relay between VLANs the frames bearing the protocols for which the VLAN boundaries are inappropriate. The non-standard relay makes the boundaries of the VLANs transparent to the relayed protocols, depriving those protocols of the benefits of VLANs. The proposed supplement will benefit users of multi-protocol LANs by permitting them to specify VLAN structures suitable for each protocol present in a LAN, and removing the need for a non-standard relay function between VLANs.