[Contents] [Prev] [Next] [Report an Error]

F

FA — Forwarding adjacency. RSVP LSP tunnel through which one or more other RSVP LSPs can be tunneled.

fabric schedulers — Identify a packet as high or low priority based on its forwarding class, and associate schedulers with the fabric priorities.

failover — Process by which a standby or secondary system component automatically takes over the functions of an active or primary component when the primary component fails or is temporarily shut down or removed for servicing. During failover, the system continues to perform normal operations with little or no interruption in service. see also GRES.

far-end alarm and control — See FEAC.

Fast Ethernet — Term encompassing a number of Ethernet standards that carry traffic at the nominal rate of 100 Mbps, instead of the original Ethernet speed of 10 Mbps. See also Ethernet, Gigabit Ethernet.

fast port — Fast Ethernet port on a J4300 Services Router, and either a Fast Ethernet port or DS3 port on a J6300 Services Router. Only enabled ports are counted. A two-port Fast Ethernet PIM with one enabled port counts as one fast port. The same PIM with both ports enabled counts as two fast ports.

fast reroute — Mechanism for automatically rerouting traffic on an LSP if a node or link in an LSP fails, thus reducing the loss of packets traveling over the LSP.

FBF — Filter-based forwarding. A filter that classifies packets to determine their forwarding path within a router. FBF is used to redirect traffic for analysis.

FCS — Frame check sequence. A calculation that is added to a frame for error control. FCS is used in HDLC, Frame Relay, and other data-link layer protocols.

FDDI — Fiber Distributed Data Interface. A set of ANSI protocols for sending digital data over fiber-optic cable. FDDI networks are token-passing networks, and support data rates of up to 100 Mbps (100 million bits). FDDI networks are typically used as backbones for wide area networks.

FEAC — Far-end alarm and control. A T3 signal used to send alarm or status information from the far-end terminal back to the near-end terminal, and to initiate T3 loopbacks at the far-end terminal from the near-end terminal.

FEB — Forwarding Engine Board. In M5 and M10 routers, provides route lookup, filtering, and switching to the destination port.

FEC — Forwarding equivalence class. Criterion used to forward a set of packets, with similar or identical characteristics, using the same MPLS label. Forwarding equivalence classes are defined in the base LDP specification and can be extended through the use of additional parameters. FECs are also represented in other label distribution protocols.

FECN — Forward explicit congestion notification. In a Frame Relay network, a header bit transmitted by the source device requesting that the destination device slow down its requests for data. FECN and BECN minimize the possibility that packets will be discarded when more packets arrive than can be handled. See also BECN.

Federal Information Processing Standards — See FIPS.

Fiber Distributed Data Interface — See FDDI.

field-replaceable unit — See FRU.

FIFO — First in, first out. Scheduling method in which the first data packet stored in the queue is the first data packet removed from the queue. All JUNOS software interface queues operate in this mode by default.

File Transfer Protocol — See FTP.

filter — Process or device that screens packets based on certain characteristics, such as source address, destination address, or protocol, and forwards or discards packets that match the filter. Filters are used to control data packets or local packets. See also packet.

filter-based forwarding — See FBF.

FIPS — Federal Information Processing Standards. Defines, among other things, security levels for computer and networking equipment. FIPS is usually applied to military environments.

firewall — Security gateway positioned between two networks, usually between a trusted network and the Internet. A firewall ensures that all traffic that crosses it conforms to the organization’s security policy. Firewalls track and control communications, deciding whether to pass, reject, discard, encrypt, or log them. Firewalls also can be used to secure sensitive portions of a local network.

firewall filter — See stateful firewall filter, stateless firewall filter.

firmware — Instructions and data programmed directly into the circuitry of a hardware device for the purpose of controlling the device. Firmware is used for vital programs that must not be lost when the device is powered off.

first in, first out — See FIFO.

flap damping — See damping.

flapping — See route flapping.

flexible bandwidth allocation — See bandwidth on demand.

Flexible PIC Concentrator — See FPC.

floating static route — Route with an administrative distance greater than the administrative distance of the dynamically learned versions of the same route. The static route is used only when the dynamic routes are no longer available. When a floating static route is configured on an interface with a dialer filter, the interface can be used for backup.

flood and prune — Method of forwarding multicast data packets in a dense-mode network. Flooding and pruning occur every 3 minutes.

flow — Stream of routing information and packets that are handled by the Routing Engine and the Packet Forwarding Engine. The Routing Engine handles the flow of routing information between the routing protocols and the routing tables and between the routing tables and the forwarding tables, as well as the flow of local packets from the router physical interfaces to the Routing Engine. The Packet Forwarding Engine handles the flow of data packets into and out of the router physical interfaces.

flow collection interface — Interface that combines multiple cflowd records into a compressed ASCII data file and exports the file to an FTP server for storage and analysis, allowing users to manipulate the output from traffic monitoring operations.

flow control action — JUNOS software syntax used in a routing policy or firewall filter. It alters the default logical processing of the policy or filter when a set of match conditions is met.

flow monitoring — Application that monitors the flow of traffic and enables lawful interception of packets transiting between two routers. Traffic flows can be passively monitored by an offline router or actively monitored by a router participating in the network.

flow-tap application — Application that uses Dynamic Tasking Control Protocol (DTCP) requests to intercept IPv4 packets in an active monitoring router and send a copy of packets that match filter criteria to one or more content destinations. Flow-tap configurations can be used in flexible trend analysis for detecting new security threats and lawfully intercepting data.

forward explicit congestion notification — See FECN.

forwarding adjacency — See FA.

forwarding classes — Affect the forwarding, scheduling, and marking policies applied to packets as they transit a routing platform. The forwarding class plus the loss priority define the per-hop behavior. Also known as ordered aggregates in the IETF Differentiated Services architecture.

Forwarding Engine Board — See FEB.

forwarding equivalence class — See FEC.

forwarding information base — See forwarding table.

forwarding table — JUNOS software forwarding information base. The JUNOS routing protocol process installs active routes from its routing tables into the Routing Engine forwarding table. The kernel copies this forwarding table into the Packet Forwarding Engine, which determines which interface transmits the packets.

FPC — Flexible PIC Concentrator. An interface concentrator on which PICs are mounted. An FPC is inserted into a slot in a Juniper Networks router. See also PIC.

fractional E1 — Interface that contains one or more of the 32 DS0 time slots that can be reserved from an E1 interface. (The first time slot is reserved for framing.)

fractional interface — Interface that contains one or more DS0 time slots reserved from an E1 or T1 interface. Fractional interfaces allow service providers to provision part of an E1 or T1 interface to one customer and the other part to another customer. The individual fractional interfaces connect to different destinations, and customers pay for only the bandwidth fraction used and not for the entire E1 or T1 interface. Fractional interfaces can be configured on both channelized PICs and PIMs and unchannelized, regular E1 and T1 PICs and PIMs.

fractional T1 — Interface that contains one or more of the 24 DS0 time slots that can be reserved from a T1 interface.

fragmentation — In TCP/IP, the process of breaking packets into the smallest maximum size packet data unit (PDU) supported by any of the underlying networks. In the Open Systems Interconnection (OSI) reference model, this process is known as segmentation. For JUNOS applications, split Layer 3 packets can then be encapsulated in MLFR or MLPPP for transport.

frame check sequence — See FCS.

Frame Relay — Efficient replacement for the older X.25 protocol that does not require explicit acknowledgment of each frame of data. Frame Relay allows private networks to reduce costs by using shared facilities between the end-point switches of a network managed by a Frame Relay service provider. Individual data-link connection identifiers (DLCIs) are assigned to ensure that each customer receives only its own traffic.

frequency-division multiplexed channel — Signals carried at different frequencies and transmitted over a single wire or wireless medium.

FRF — Frame Relay Forum. A technical committee that promotes Frame Relay by negotiating agreements and developing standards.

FRF.15 — End-to-end Frame Relay Implementation Agreement. An implementation of MLFR using multiple virtual connections to aggregate logical bandwidth for end-to-end Frame Relay. Released by the Frame Relay Forum.

FRF.16 — Multilink Frame Relay Implementation Agreement. An implementation of MLFR in which a single logical connection is provided by multiplexing multiple physical interfaces for user-to-network interface and network-to-network interface (UNI/NNI) connections. Released by the Frame Relay Forum.

FRU — Field-replaceable unit. A router component that customers can replace onsite.

FTP — File Transfer Protocol. Application protocol that is part of the TCP/IP protocol stack. Used for transferring files between network nodes. FTP is defined in RFC 959.

Full — OSPF adjacency state that represents a fully functional neighbor relationship.

fxp0 — See management Ethernet interface.

fxp1 — JUNOS software permanent interface used for communications between the Routing Engine and the Packet Forwarding Engine. This interface is not present in all routers.

fxp2 — JUNOS software permanent interface used for communications between the Routing Engine and the Packet Forwarding Engine. This interface is not present in all routers.

[Contents] [Prev] [Next] [Report an Error]