PFE

Packet Forwarding Engine

The Packet Forwarding Engine provides Layer 2 and Layer 3 packet switching, route lookups, packet forwarding, and route lookup functions.

(definition from juniper.net)

PRE

Packet Routing Engine

OSPF

Open Shortest Path First

OSPF is an adaptive routing protocol for internet protocol(IP) networks.

It uses a link state routing algorithm and falls into the group of interior routing protocols, operating within a single autonomous system (AS). It is defined as OSPF Version 2 in RFC 2328

(1998) for IPv4.^[1] The updates for IPv6 are specified as OSPF Version 3 in RFC 5340

(2008).^[2]

OSPF is perhaps the most widely-used interior gateway protocol (IGP) in large enterprise networks. IS-IS, another link-state routing protocol, is more common in large service provider networks. The most widely-used exterior gateway protocol is the Border Gateway Protocol (BGP), the principal routing protocol between autonomous systems on the Internet.

TTL

Time to Live

TTL is a limit on the period of time or number of iterations or transmissions in computer and computer network technology that a unit of data (e.g. a packet) can experience before it should be discarded.

RIP

Routing Information Protocol

RIP is a dynamic protocol used in local and wide area networks.

As such it is classified as an interior gateway protocol (IGP). It uses the distance-vector routing algorithm. It was first defined in RFC 1058

(1988). The protocol has since been extended several times, resulting in RIP Version 2 (RFC 2453

). Both versions are still in use today, although they are considered to have been made technically obsolete by more advanced techniques such as Open Shortest Path First (OSPF) and the OSI protocol IS-IS. RIP has also been adapted for use in IPv6 networks, a standard known as RIPng (RIP next generation) protocol

PPP

Point to Point Protocol

Point-to-Point Protocol, or PPP, is a data link protocol commonly used in establishing a direct connection between two networking nodes. It can provide connection authentication, transmission encryption privacy, and compression.

PPP is used over many types of physical networks including serial cable, phone line, trunk line, cellular telephone, specialized radio links, and fiber optic links such as SONET. Most Internet service providers (ISPs) use PPP for customer dial-up access to the Internet. Two encapsulated forms of PPP, Point-to-Point Protocol over Ethernet (PPPoE) and Point-to-Point Protocol over ATM (PPPoA), are used most commonly by Internet Service Providers (ISPs) to establish a Digital Subscriber Line (DSL) Internet service connection with customers.

PPP is commonly used as a data link layer protocol for connection over synchronous and asynchronous circuits, where it has largely superseded the older Serial Line Internet Protocol (SLIP) and telephone company mandated standards (such as Link Access Protocol, Balanced (LAPB) in the X.25 protocol suite). PPP was designed to work with numerous network layer protocols, including Internet Protocol (IP), Novell's Internetwork Packet Exchange (IPX), NBF and AppleTalk.

PPP is also used over broadband connections. RFC 2516

describes Point-to-Point Protocol over Ethernet (PPPoE), a method for transmitting PPP over Ethernet that is sometimes used with DSL. RFC 2364

describes Point-to-Point Protocol over ATM (PPPoA), a method for transmitting PPP over ATM Adaptation Layer 5 (AAL5), which is also a common alternative to PPPoE used with DSL.

SNMP

Simple Network Management Protocol

Simple Network Management Protocol (SNMP) is an "Internet-standard protocol for managing devices on IP networks. Devices that typically support SNMP include routers, switches, servers, workstations, printers, modem racks, and more.”^[1] It is used mostly in network management systems to monitor network-attached devices for conditions that warrant administrative attention. SNMP is a component of the Internet Protocol Suite as defined by the Internet Engineering Task Force (IETF). It consists of a set of standards for network management, including an application layer protocol, a database schema, and a set of data objects.^[2]

LAN

Local Area Network

WAN

Wide Area Network

A wide area network (WAN) is a computer network that covers a broad area (i.e., any network whose communications links cross metropolitan, regional, or national boundaries).^[1] This is in contrast with personal area networks (PANs), local area networks (LANs), campus area networks (CANs), or metropolitan area networks (MANs) which are usually limited to a room, building, campus or specific metropolitan area (e.g., a city) respectively.

PSTN

Public Switched Telephone Network

The public switched telephone network (PSTN) is the network of the world's public circuit-switched telephone networks. It consists of telephone lines, fiberoptic cables, microwave transmission links, cellular networks, communications satellites, and undersea telephone cables all inter-connected by switching centers which allows any telephone in the world to communicate with any other. Originally a network of fixed-line analog telephone systems, the PSTN is now almost entirely digital in its core and includes mobile as well as fixed telephones.

MPLS

Multiple Protocol Labeling Switch

Multiprotocol Label Switching (MPLS) is a mechanism in high-performance telecommunications networks which directs and carries data from one network node to the next with the help of labels. MPLS makes it easy to create "virtual links" between distant nodes. It can encapsulate packets of various network protocols.

SF

SuperFrame

SF is a framing standard for T1s also called D4 or D3/D4 framing.

In order to determine where each channel is located in the stream of data being received, each set of 24 channels is aligned in a frame. The frame is 192 bits long (8 * 24), and is terminated with a 193rd bit, the framing bit, which is used to find the end of the frame.

In order for the framing bit to be located by receiving equipment, a pattern is sent on this bit. Equipment will search for a bit which has the correct pattern, and will align its framing based on that bit. The pattern sent is 12 bits long, so every group of 12 frames is called a Super Frame. The pattern used in the 193rd bit is 1000 1101 1100.

ESF

Extended SuperFrame

Extended Super Frame (ESF) is a T1 framing standard, sometimes called D5 framing because it was first used in the D5 Channel Bank.

In ESF, a superframe is 24 frames long, and the 193rd bit of each frame is used in the following manner:

• Frames 4, 8, 12, 16, 20, and 24 are used to send the framing pattern, 001011

• Frames 1, 3, 5, 7, 9, 11, 13, 15, 17, 19, 21 and 23 are used for the data link (totalling half of all framing bits, or 4000 bits per second)

• Frames 2, 6, 10, 14, 18, and 22 are used to pass the CRC total for each super frame.

MAC

Media Access Control

A Media Access Control address (MAC address) is a unique identifier assigned to network interfaces for communications on the physical network segment

OUI

Organizationally Unique Identifier

OUI is a unique 24-bit number that identifies a vendor, manufacturer, or other organization