P

package

A collection of files that make up a JUNOS software component.

packet data protocol (PDP)

Network protocol, such as IP, used by packet data networks connected to a GPRS network.

Packet Forwarding Engine

The architectural portion of the router that processes packets by forwarding them between input and output interfaces.

Packet Loss Priority (PLP)

Internal router designation that represents a greater probability of dropping a particular IP packet based on configured class of service settings. The priority is assigned to a packet when it enters the router and can be modified by a firewall filter.

partial sequence number PDU (PSNP)

Packet that contains only a partial list of the LSP headers in the IS-IS link-state database.

path attribute

Information about a BGP route, such as the route origin, AS path, and next- hop router.

PathErr

RSVP message that indicates an error has occurred along an established LSP. The message is advertised upstream toward the ingress router and it doesn't remove any RSVP soft state from the network.

PathTear Message

RSVP message that indicates the established LSP and its associated soft state should be removed by the network. The message is advertised downstream hop-by-hop toward the egress router.

path-vector protocol

A routing protocol definition that describes the direction to the destination and the network path used to reach the destination. This often describes the functionality of BGP.

peer

An immediately adjacent router with which a protocol relationship has been established. Also called a neighbor.

penultimate hop popping (PHP)

A mechanism used in an MPLS network that allows the transit router prior to the egress to perform a label pop operation and forward the remaining data (often a native IPv4 packet) to the egress router.

penultimate router

The last transit router prior to the egress router in an MPLS label- switched path.

Perfect Forward Secrecy (PFS)

A condition derived from an encryption system that changes encryption keys often and ensures that no two sets of keys have any relation to each other. The advantage of PFS is that if one set of keys is compromised, only communications using those keys are at risk. An example of a system that uses PFS is Diffie-Hellman.

Peripheral Component Interconnect (PCI)

Standard, high-speed bus for connecting computer peripherals. Used on the Routing Engine.

permanent virtual circuit (PVC)

A logical Layer 2 connection between two network devices. The network path is preengineered and configured on each device in the network supporting the PVC.

Personal Computer Memory Card International Association (PCMCIA)

Industry group that promotes standards for credit card-size memory or I/O devices.

Physical Interface Card (PIC)

A network interface-specific card that can be installed on a FPC in the router.

PIC I/O Manager ASIC

Juniper Networks ASIC responsible for receiving and transmitting information on the physical media. It performs media-specific tasks within the Packet Forwarding Engine.

PLP bit

Packet Loss Priority bit. Used to identify packets that have experienced congestion or are from a transmission that exceeded a service provider's customer service license agreement. This bit can be used as part of a router's congestion control mechanism and can be set by the interface or by a filter.

policing

Applying rate limits on bandwidth and burst size for traffic on a particular interface or IPv4 prefix.

Policing Equivalence Classes (PEC)

In traffic policing, a set of packets that is treated the same by the packet classifier.

pop

Removal of the last label, by a router, from a packet as it exits an MPLS domain.

Point-to-Point Protocol (PPP)

Link-layer protocol that provides multiprotocol encapsulation. It is used for link-layer and network-layer configuration.

poison reverse

Method used in distance-vector networks to avoid routing loops. Each router advertises routes back to the neighbor it received them from with an infinity metric assigned.

policy chain

The application of multiple routing policies in a single location. The policies are evaluated in a predefined manner and are always followed by the default policy for the specific application location.

precedence bits

The first three bits in the ToS byte. On a Juniper Networks router, these bits are used to sort or classify individual packets as they arrive at an interface. The classification determines the forwarding class to which the packet is directed upon transmission.

preference

Desirability of a route to become the active route. A route with a lower preference value is more likely to become the active route. The preference is an arbitrary value in the range 0 through 4,294,967,295 that the routing protocol process uses to rank routes received from different protocols, interfaces, or remote systems.

preferred address

On an interface, the default local address used for packets sourced by the local router to destinations on the subnet.

prefix-length-range

JUNOS software routing policy match type representing all routes that share the same most significant bits. The prefix length of the route must also lie between the two supplied lengths in the route filter.

primary address

On an interface, the address used by default as the local address for broadcast and multicast packets sourced locally and sent out the interface.

primary contributing route

The contributing route with the numerically smallest prefix and smallest JUNOS software preference value. This route is the default next hop used for a generated route.

primary interface

Router interface that packets go out when no interface name is specified and when the destination address does not imply a particular outgoing interface.

protocol address

The logical Layer 3 address assigned to an interface within the JUNOS software.

protocol data unit (PDU)

The basic data structure used by the IS-IS routing protocol to form adjacencies and exchange routing information.

protocol families

The grouping of logical properties within an interface configuration. The JUNOS software supports the inet, iso, mpls, and inet6 families.

Protocol Independent Multicast (PIM)

A protocol-independent multicast routing protocol. PIM sparse mode routes to multicast groups that might span wide-area and interdomain internets. PIM dense mode is a flood-and-prune protocol.

protocol preference

A 32-bit value assigned to all routes placed into the routing table. It is used as a tiebreaker when multiple exact routes are placed into the table by different protocols.

provider edge (PE) router

A router in the service provider's network that can have customer edge (CE) devices connected and that participates in a virtual private network (VPN).

provider router

Router in the service provider's network that does not attach to a customer edge (CE) device.

Prune message

PIM message sent upstream to a multicast source or the RP of the domain. It requests that multicast traffic stop being transmitted to the router originating the message.

public land mobile network (PLMN)

A telecommunications network for mobile stations.

push

Addition of a label or stack of labels, by a router, to a packet as it enters an MPLS domain.