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A
AAL
- ATM Adaption Layer. [back to top]
access list
- Lists of IP addresses, as-paths or communities that are used to identify routes for filtering or manipulation. [back to top]
adjacency
- Two routers that have synchronized their link-state advertisement databases. [back to top]
administrative distance
- A metric BGP used to prefer a route learned from one protocol over the same route learned from another protocol. [back to top]
admission control
- The function internal to the router/switch device that determines whether a requested connection can be established. This function is used for IntServ and Traffic Engineering. [back to top]
AF
- Assured Forwarding. [back to top]
aggregate
- Two or more flows through the same inbound and outbound interfaces sharing the same IP precedence or DSCP. [back to top]
AIS
- Alarm Indication Signal. [back to top]
API
- Application Programmable Interface. [back to top]
area
- A group of routers that share the same routing protocol and the same topology database. [back to top]
area border router
- A router that connects areas. This router runs level-2 routing. [back to top]
AS
- Autonomous system. [back to top]
ASIC
- Application Specific Integrated Circuit. [back to top]
as-path access list
- Access lists that enable you to control access by specifying which autonomous system paths are permitted or denied. [back to top]
ATM
- Asynchronous Transfer Mode. [back to top]
authentication
- Providing proof of privilege by labeling messages with a predefined password. [back to top]
autonomous system
- A collection of routers under the control of a single administrative group sharing the same group of policies. [back to top]
autonomous system path
- A list of all the autonomous systems between a route's origin and destination. [back to top]
B
backend
- In ASIC design, backend refers to the whole tool flow required to go from a Verilog RTL design to silicon on a chip. Our tool flow, in part, is Synopsys> motive>placement>routing>LSI, where masks are created for manufacturing the chip. [back to top]
bay controller
- The bay controller is a circuit board operating under the direction of a server. There will be two of these circuit boards per TSR offering redundant controllers. The bay controller: monitors and controls the blowers, monitors the -48v bay power supplies, provides a low speed communication channel to/from each module in the bay for module bring-up, provides an interface to the server, controls the bay LED alarm indicators, and provides control circuits for central office visual and audible alarm indicators. [back to top]
BE
- Best Effort. Network attempts to deliver a packet to the destination without guarantee and resource allocation. This is the default forwarding mechanism in the Internet. When QoS is enabled and IP precedence is assigned, packets with IP precedence set to 0 are forwarded as best effort. [back to top]
BGP
- Border Gateway Protocol. BGP is a protocol that chooses the best destination route when faced with multiple routes to the same destination. [back to top]
BGP4
- Border Gateway Protocol Version 4. [back to top]
BIP
- Breaker Interface Panel. [back to top]
borehole routes
- When two Delta values are zero, then the only path to the other module is via the non-zero delta-z axis. In this case we hae only one route to the other module. We call this a borehole. [back to top]
BPS
- Bits Per Second. [back to top]
broken paths
- When a physically shortest path that stays inside the bounds of the delta vector does not exist, as a result of some broken, or even non-existant links between modules. Or, when the physically shortest path really does exist, but it is longer than it would be, if all of the links were available. [back to top]
BSR
- Bootstrap Router. A BSR collects and distributes routing information to multicast routers within a multicast domain. [back to top]
bundle
- A set of connections that share a common single failure mode. A particular connection may be a member of one or more bundles. [back to top]
C
CBR
- Constant Bit Rate. [back to top]
CBQ
- Class Based Queuing. [back to top]
CES
- Circuit Emulation Service. [back to top]
circuit relay
- A mechanism for transferring circuit traffic (for example, ATM VC or Frame Relay DLC) between two nodes using MPLS or IP/UDP as a transport. [back to top]
CIR
- Committed Information Rate. [back to top]
CIDR
- Classless Interdomain Routing. CIDR is based on route aggregation and a technique supported by BGP4. With CIDR, routers group routes together in order to eliminate the majority of routing information carried by the core routers. Using CIDR, several IP networks appear to networks outside the group as a single, larger entity. [back to top]
classification
- Local mapping of the IP precedence or DSCP value to a packet treatment. [back to top]
class of service
- The quality of service assigned to an IP precedence or DSCP value. [back to top]
cli
- Command-line Interface. The TSR system uses an industry standard command-line interface to provision, modify, and monitor the control server and interfaces on the associated router modules. [back to top]
client
- An internal neighbor that receives its route updates from a route reflector. [back to top]
CLLI codes
- CLLI codes are bar codes used for inventory purposes. [back to top]
cluster
- The combined structure of route reflectors and clients. [back to top]
CO
- Central Office. [back to top]
COBS
- Constant Overhead Byte Stuffing. [back to top]
cohorts
- Defined to be modules who share a single fabric channel. Although it is not physically required by the TSR architecture, we choose to designate the cohort of any module as the unique module that is physically separated exactly halfway around each maximum size ring. For example, a cohort for a module <0,0,0> is <5,5,3>. [back to top]
community
- A group of routers with the same community attribute. [back to top]
community-list
- Access list that enables you to control access by specifying which communities are permitted or denied. [back to top]
congestion
- Full utilization of resources: bandwidth, buffers, and queues. [back to top]
congestion avoidance
- QoS mechanisms such as RED that when employed prevent congestion before it actually occurs. [back to top]
congestion control
- QoS mechanisms such as WFQ that handle forwarding when congestion is experienced. Such mechanisms prioritize packets based upon the assigned packet treatments. [back to top]
congestion management
- QoS mechanisms for congestion avoidance and congestion control. [back to top]
confederation
- An autonomous system that is divided into multiple mini-autonomous systems. From outside, the confederation of mini-autonomous systems looks like a single autonomous system. [back to top]
connection
- A physical bidirectional edge between two nodes. A connection may be, for example, a SONET path. A connection has fixed delay, fixed bandwidth and fixed delay jitter properties. [back to top]
control load
- Best effort service through a non-congested network. Latency and loss should be at a minimum. [back to top]
cost
- A value assigned to an interface to assist the routing algorithm in determining the best path for traffic to a destination. The cost not only takes into account the number of hops to a destination, but also the bandwidth of the interface. [back to top]
CPLD
- Complex Programmable Logic Device. This is a programmable IC that retains its logic function in a nonvolatile memory. It is hard-programmed with its function during manufacturing. It provides fast, predictable timing. [back to top]
CPM
- Custom Processor Module. On the TSR system, the CPM is a module that works as a daughter card board to the switch board. It is a standalone processing agent responsible for all module control and the processing of packets not handled by the module's ASICs. [back to top]
CS
- Convergence Sublayer is responsible for mapping higher-layer protocol requests for AAL, SAR, and ATM services. [back to top]
CV
- Coding Violation. [back to top]
CVS
- CVS is a revision control system. [back to top]
D
dampening
- A process of suppressing the advertisement of routes that are have been repeatedly withdrawn and readvertised. [back to top]
deflection paths
- In the normal case, a fully connected fabric, each module can directly route messages to every other module. But in a broken fabric, or in some future extended fabrics, the total distance between modules (in worst case) may exceed the maximum number of hops supported in the flit format. When this happens, each modules may independently select "nearby" modules that can relay a message by generating another source path. This forwards the message further towards its ultimate destination. The number of deflectionsis subject to hardware control. [back to top]
delta vector
- The difference in the spatial positions of any two modules can be described with a delta vector <Dx, Dy, Dz>. Instead of eploring every available link from each module to its neighbors in typical Dijkstra fashion, we instead only examine links in the directions Sx, Dy, and Dz. [back to top]
demux
- Demux converts recovered serial clock and data to 16-bit data bus and clock/16. [back to top]
DiffServ
- DiffServ is the current approach taken by the IETF to enable QoS over the Internet and to systematically resolve the scaleability problem of the IntServ architecture. [back to top]
display filtering
- Determines which messages already logged on the server will display to the console or monitor. [back to top]
diversity
- A measure of the degree of fate separation between different elements. For example, a set of connections with physical diversity means that those connections do not share single failure modes. [back to top]
DLCI
- Data Link Connection Identifier. The Frame Relay virtual circuit number corresponding to a particular destination that is part of the Fame Relay header and is usually 10 bits long. [back to top]
domain
- (OSPF) A group of routers sharing a common routing protocol. [back to top]
domain
- (IS-IS) Any group of routers that are administered by a single organization. [back to top]
DPM
- Downtime Performance Measurements. DPM are taken from Bellcore's GR-929-CORE specifications. [back to top]
DR
- Designated Router. An OSPF router elected via protocol to be represented in the Link State Database (LSDB) as the source of adjacencies on a broadcast Ethernet network. [back to top]
DSCP
- Differentiated Services Code Point. [back to top]
E
ECMP set
- Equal Cost Multipath Path. Each ECMP set consists of up to four IP routes with the same destination address and network mask, but different gateway addresses. The IP routes can be either standard routes or composite links. [back to top]
ECN
- Explicit Congestion Notification. [back to top]
EDA
- Electronic Design Automation. Buzzword for software to help design hardware. [back to top]
edge
- A connection between two vertices in a graph that describes the topology of the network. This term is used generically in the topology at any layer. [back to top]
EfL
- FIFO is empty; all packet data has been extracted. [back to top]
EF
- Expedited Forwarding. [back to top]
EFTs
- Electrical Fast Transients. [back to top]
egress
- The point of output from a Label Switched Path (LSP). [back to top]
electrical/optical (E/O) converter
- The E/O converter converts the electrical STS48c to an optical signal. [back to top]
EMC
- Electromagnetic Compatibility. [back to top]
end system
- (IS-IS) A host. [back to top]
EOP
- End of Packet. [back to top]
ES
- Errored Second. [back to top]
ESD
- Electrostatic Discharge. [back to top]
external peer
- Directly connected neighbors (peers) who are not members of the same autonomous system. [back to top]
exterior gateway protocol
- Routing protocols that operate between domains. [back to top]
equidistant modules
- When the Dx value is +5 AND -5 at the same time, then the modules are equidistant in that axis. [back to top]
F
FBE
- FIFO Byte Enable. [back to top]
FEBE
- Far End Block Error Detection. [back to top]
FEC
- Forwarding Equivalence Class. An IP prefix and CIDR mask used to match IP packet destination addresses to specific Label Switch Path (LSP) admission. [back to top]
FIFO
- First In First Out.A memory IC that transmits data in the same order as received. [back to top]
flow
- An individual uni-directional data stream uniquely identified by IP source address, IP destination address, and IP precedence or DSCP. [back to top]
flits
- Flow control digits. From wormhole routing, flits are a flow control protocol that segment a message into equal size cells. [back to top]
Flute
- OC12 and Quad-OC3 input/output framer. [back to top]
FMEA
- Failure Modes and Effects Analysis. [back to top]
forwarding rate
- The maximum number of bits per second (bps) or packets per second (pps) transmitted in one interface and out another interface of a routing/switch device. [back to top]
free hop
- After the first hop has been taken, the route follows the usual physically shortest path. This is also called free hop. [back to top]
FPGA
- Field Programable Gate Array. This is a programmable IC that retains its logic function in volatile memory. It must have its function loaded into it at power-up. It provides high-density, low-cost logic. [back to top]
FRP
- Fabric Routing Protocol. FRP helps to correctly determine the addition and loss of routing neighbors and to exchange link-state information containing interface state information, link congestion, and control server subnet reachability. [back to top]
FTP
- File Transfer Protocol. [back to top]
full mesh
- BGP requires that all systems running BGP within an autonomous system to establish peering sessions with one another. [back to top]
FWQ
- Fair Weighed Queuing. [back to top]
G
GigE
- Gigabit Ethernet [back to top]
GFC
- General Flow Control. [back to top]
GPRAs
- Generic Packet Rate Algorithm. [back to top]
GPRSs
- Generic Packet Rate Shaper. [back to top]
guaranteed service
- Absolute conformance to the Service Level Agreement (SLA) without relative comparison to other traffic. [back to top]
H
HA
- High Availability. [back to top]
HDL
- Hardware Description Language. Avici uses Verilog, as it is the most widely used and accepted at this time. [back to top]
HDLC
- High Level Data Link Control. HDLC is an ISO protocol where control information is always placed in the same position. [back to top]
HEC
- Hardware Error Control. [back to top]
hop
- An edge between two nodes in the Layer 3 topology that is capable of transferring packets between those two nodes. A hop may be layered over a single LSP, a composite path (each of whose members may be a single or protected LSP), a single protected LSP, a link or composite link. [back to top]
I
ICMP
- Internet Control Message Protocol. ICMP is a network layer Internet protocol that reports errors and provides other information relevant to IP packet processing. (RFC 792) [back to top]
IETF
- Internet Engineering Task Force. [back to top]
IGP
- Interior Gateway Protocol. IGP is an Internet protocol used to exchange routing information within an autonomous system. Some examples of common Internet IGPs include IGRP, OSPF, and RIP. [back to top]
IGRP
- Interior Gateway Routing Protocol. [back to top]
ILIM
- Integrated Local Management Interface. [back to top]
ingress
- The point of input into a Label Switched Path (LSP). [back to top]
input filtering
- Determines which messages are forwarded to the server at message generation. [back to top]
input framing ASIC
- The input framing ASIC performs the SONET/SDH termination and layer 2 processing (generation of packet descriptors, storage of received frames into packet memory and packet policing). [back to top]
integrated service
- An IP architectural model for end-to-end resource reservation to support real-time and best effort flows. (RFC 2005) [back to top]
inter-area routing protocol
- Routing protocols that operate between domains. [back to top]
intermediate system
- (IS-IS) A router. [back to top]
internal peer
- Neighbors (peers) who are members of the same autonomous system. [back to top]
interior gateway protocol
- Routing protocols that operate within the domain. [back to top]
internal router
- (OSPF) A router with all interfaces in the same area. [back to top]
intra-area routing protocol
- Routing protocols that operate within the domain. [back to top]
IP
- Internet Protocol. [back to top]
IP Multicast
- An internet protocol designed to provide data transmission to multiple users while maximizing network resources. [back to top]
IP precedence
- The first 3 bits in the ToS-byte. IP precedence may be of value 0-7, where 0 is highest and 7 is lowest. [back to top]
IS-IS
- Integrated intermediate-system to intermediate-system (IS-IS). The TSR system supports ISO 10589:1992(E) of IS-IS as it relates to IP networks. [back to top]
ISP
- In-System Programmable. This is a programmable IC that may have its logic function loaded into it without moving it from the printed-circuit board. [back to top]
ISSR
- Industry Standard Switch Router. [back to top]
J
jitter
- Refers to variations in delay, or the phase shift of digital pulses over a transmission medium. [back to top]
JTAG
- Joint Test Action Group. This is a serial electrical test interface built into many large ICs including ASIC, CPLD, and FPGA. It allows efficient automated testing. [back to top]
K
keepalive timer
- The number of seconds a BGP router will wait for a keep-alive message from a neighbor before deciding the connection is down. [back to top]
L
label
- A label is a 20 byte shim header placed between the datalink layer and the network layer. The label is used to indicate the next hop by virtue of a lookup table on the LSR. [back to top]
latency
- Elapsed time for the last bit of a packet to be transmitted, routed through the router (or network), and received at the destination. Time of flight includes propagation delay and the processing, queuing, and transmission delay for the routing/switching device. [back to top]
LDP
- Label Distribution Protocol. [back to top]
level-1 router
- (IS-IS) Routers that handle traffic within an area. [back to top]
level-2 router
- (IS-IS) Routers that handle traffic between areas. [back to top]
line card
- Front-end media interface card. [back to top]
link state routing
- Maintains a routing table by exchanging changes in link-state information with neighboring routers. [back to top]
link state database
- A database containing the latest link-state advertisements received from neighbors. [back to top]
load spreading
- Each modules wants to distribute its traffic load from itself to every other module over as many "fabric links" as possible, such that the diffferent paths have a minimum number of links in common. Also referred to as "route diversity." [back to top]
local preference
- A routing update attribute that determines the order in which routes to the same destination are installed in the routing table. Paths with higher local preferences are preferred. [back to top]
LOF
- Loss of Frame. [back to top]
logging
- The recording of system generated information for the purpose of monitoring TSR system operation. [back to top]
loopback interface
- A software configuration that enables BGP connections to internal peers to stay up no matter what interface is used to reach that peer. [back to top]
LOP
- Loss of Pointer. [back to top]
LOS
- Loss of Signal. [back to top]
loss
- The number of packets or bytes that are dropped for a flow or stream. [back to top]
LSDB
- (OSPF) Link State Database. [back to top]
LSP
- Label Switched Path. A series of segments that use MPLS to form a unidirectional path through the network. [back to top]
LSR
- Label Switch Router. A router capable of supporting MPLS. [back to top]
LVSD
- Low Voltage Shut Down. An LVSD circuit detects a low input voltage (36-37 Vdc) and shuts down the module. [back to top]
M
marking
- Setting of the IP precedence or DSCP fields based upon locally configured policy. This is typically done at the network edge but may also be performed in the core when required. [back to top]
max-th
- RED maximum threshold above which there is 100 percent discard. [back to top]
MED
- Multi-exit Discriminator. A metric that BGP uses to provide hints to external neighbors about the preferred path into an autonomous system. [back to top]
message filtering
- A means of limiting log messages that either display to the console, or are written to disk. [back to top]
MT
- Message Transport. [back to top]
metering
- Monitoring of the traffic pattern of each flow against the traffic Service Level Agreement (SLA). Non-conforming packets are either re-marked or dropped. [back to top]
MIBs
- Management Information Base. A MIB is a directory listing the logical names of all information resources residing in a network and pertinent to the network's management. [back to top]
min-th
- RED minimum threshold below which there is 0 percent packet discard. [back to top]
mLAN
- Maintenance LAN. A maintenance LAN augments the switching fabric to provide a mechanism for servers to intercommunicate with all system resources regardless of their switch fabric connectivity. [back to top]
module
- Line card and switch card assembled together. [back to top]
MPLS
- Multi-protocol Label Switching. A method of switching packets through a network in which each packet is marked with a label that is used at each node to determine the next segment in the path. [back to top]
MPP
- Massively Parallel Processor. MPP distributes memory amongst many computational units and employs a fast, robust communication fabric that interconnects the units. [back to top]
MOA
- Managed Object Agent. [back to top]
MTBF
- Mean-time Between Failures. [back to top]
MTTR
- Mean-time To Repair. [back to top]
MUX
- The MUX converts the 16 bit data bus into a serial format. [back to top]
MVIF
- Multicast Virtual Interface. A MVIF displays a numerical representation of actual interface IP addresses in a multicast domain. [back to top]
N
NAP
- Network Access Point. [back to top]
neighbor
- A router that is directly connected to another router or connected through a virtual link. Also known as a peer. [back to top]
NET
- (IS-IS) Network Entity Title. This is a field that consists of the Network Service Access Point (NSAP) and a selector. [back to top]
network routing
- When the source switch simply provides an address of the destination and leaves it up to the fabric to transport the message. [back to top]
NNI
- Network to Network Interface. [back to top]
NOC
- Network Operations Center. [back to top]
node
- (IS-IS) A participant in a routing domain. Either a router or a host. [back to top]
non-conforming
- A packet that violates the service profile. [back to top]
NSAP
- (IS-IS) Network Service Access Point. An access format that can be encoded in 20 octets. [back to top]
NSSA
- Not So Stubby Areas. [back to top]
NTF
- No Trouble Found. [back to top]
NTPv3
- Network Time Protocol (RFC 1305). [back to top]
NVRAM
- Protected RAM for the storage of logging messages prior to transport to the server. [back to top]
O
OAM terminal
- Operations, Administration, and Maintenance terminal. [back to top]
OSPF
- Open Shortest Path First. [back to top]
output framing ASIC
- Creates and schedules packet insertion into the SONET payload to conform with layer 2 and 3 QoS contracts. Also performs all SONET transmit side termination functions. [back to top]
over provisioning
- Surplus bandwidth capacity to avoid congestion during high-demand periods. [back to top]
P
PHB
- Per hop behavior. [back to top]
P0 plate
- Pronounced as P-zero, this plate is similar in size to the TSR backplane and is located in front of the signal backplane. [back to top]
P1 plate
- The P1 plate is similar in size to the P0 plate and is located behind the signal backplane. [back to top]
packet treatments
- Packet treatments are a means of grouping packet related parameter sets such as queue and Random Early Detection (RED). [back to top]
PATH/RESV
- Path and reservation messages used by RSVP to signal label request and distribution respectively. [back to top]
PATRICIA
- Practical Algorithm To Retrieve Information Coded in Alphanumeric. [back to top]
PBM
- Policy based managers. [back to top]
PDU
- Protocol data unit. [back to top]
peer group
- A group of neighbors that share the same routing policies. [back to top]
PHB
- Per Hop Behavior. PHB is the packet treatment a packet is to receive at each hop as it is forwarded through the network. The treatment can be dependent upon either the IP precedence or DSCP value and may be specified in relative or absolute terms. [back to top]
PIM
- Protocol Independent Multicast. PIM is an internet protocol that enables routers to accept and forward multicast traffic. [back to top]
PIM-SM
- Protocol Independent Multicast-Sparse Mode. PIM-SM is a multicast protocol designed for multicast transmission in Wide Area Networks. PIM-SM uses a central distribution router called a Rendezvous Point (RP) and a shared tree distribution method. [back to top]
platform One of the hardware entities of the TSR, either the server, module or bay controller.
platformID
- The platform identifier used to identify a specifc platform. For example, a platformID can specify one of the following platforms: server 1, server 2, module 1, module 2, baycontroller 1, baycontroller 2. [back to top]
PLL
- Phase-Locked Loop. A circuit technique that uses feedback to create precisely timed copies of clocks. [back to top]
PLM
- Path Signal Label Mismatch. [back to top]
PNNI
- Private Network to Network Interface. [back to top]
policing
- Packet-by-packet monitoring function that ensures a host does not violate its pre-established traffic characteristics. [back to top]
policy
- Rules applied to QoS that are configured at the routing/switching devices in the network. It can be a packet treatment, constraints for traffic engineered tunnels, a traffic filter, or a routing filter. [back to top]
POPs
- Point of Presence. The POP is a long distance carrier's office in your local community. [back to top]
POS
- Point of Service or point of presence. [back to top]
POST
- Power on Self Test. [back to top]
PPP
- Point-to-Point Protocol. [back to top]
PPP negotiation time-out
- Amount of elapsed time (in seconds) allowed between LCP/IPCP/OSICP negotiations before the next cycle of negotiations is started. [back to top]
PPS
- Packets Per Second. [back to top]
prefix-based access lists
- Access lists that enable you to control access by specifying which network prefix numbers are permitted or denied. [back to top]
prioritization
- Assignment of a packet treatment to favor an IP precedence or DSCP over another. [back to top]
protected label switch path
- A set of LSPs between two nodes, which has the property that at each switch on the path there are two or more alternate downstream segments. At any time, only one of the alternate downstream segments is in use at each switch. The purpose of a protected LSP is to provide fast-failover from a failed segment to a working segment. [back to top]
provision
- Configuration of policy at each node to enable and maintain QoS in the network. [back to top]
PVC
- Permanent Virtual Connection. [back to top]
Q
QoS
- Quality of Service. QoS can be defined as the ability for a user of a specific application to obtain service with predictable performance over some reasonable period of time that permits the application to operate in an acceptable manner. Each message class may have up to 8 levels of QoS defined for transport. Each level of QoS defines transport attributes such as reliable, in-order, queue limits, number of retries, timeouts, latency, and lifetime. [back to top]
QoS Mode 1
- Avici definition for first release of QoS, consisting of IP TOS classification and 8 output queues. [back to top]
queue depth
- The number of packets or bytes in a queue. [back to top]
queue size
- The real or artificially configured size of a queue. [back to top]
R
RBOC
- Regional Bell Operating Company. RBOCs were derived out of the old AT&T Bell System. [back to top]
RDI
- Remote Defect Indication. [back to top]
recalculation of optimum routes
- In a normal network, a change in the status of a link on one router must be propagated as rapidly as possible to all other routers in the network. The routers must (more or less) immediately recalculate their routing tables. This is necessary because of the non-independence of the routers. For example, in the worst case, routing loops can form if some routers recaluclate their routes, and others do not. In TSR fabric, the addition or removal of a link, or a module, may or may not be of any immediate importance. For example, if a path becomes unusable, it will be replaced by a new path, but other paths to the same module may be unaffected. [back to top]
RED
- Random Early Detection. A traffic conditioner that is used for congestion avoidance and notification that randomly drops packets in queues when congestion is detected. [back to top]
redistribution
- A process that takes routing information from one routing domain, translates the metrics so they can be understood by another IP protocol, and injects the translated routes into another routing domain. [back to top]
resource allocation
- Reservation of resources for new connections admitted by the admission control function. [back to top]
RFI
- Remote Failure Indication. [back to top]
RMON
- Remote Monitoring. Described in RFC 1271, RMON is a MIB agent specification that defines functions for the remote monitoring of networked devices. The RMON specification provides numerous monitoring, problem detection, and reporting capabilities. [back to top]
route diversity
- See "Load Spreading." [back to top]
route map
- A set of match criteria (that identifies one or more attributes in a route update) and set options (that define what actions to take if the match criteria are met). [back to top]
route reflector
- A router configured to advertise routes learned from clients to other clients, thus eliminating the need for clients to form peering relationships with one another. [back to top]
router ID
- The unique identifier for the router. In OSPF, this is the lowest interface address on the router. [back to top]
router module
- The TSR system supports router modules in combinations of module speeds in a single chassis backplane. Router modules support PPP, ATM, and MPLS protocols. Router modules interconnect to server modules throught a 100BaseT Ethernet cable (RJ-45). [back to top]
RP
- Rendezvous Point. An RP is a central distribution router for multicast traffic within a multicast domain. [back to top]
RPC
- Remote Procedure Call. An RPC is a call infrastructure that communicates all SNMP sets and requests between the control server and the bay controller. [back to top]
RPF
- Reverse Path Forwarding. RPF is a routing mechanism that restricts duplicate multicast traffic on incoming interfaces by allowing only one incoming interface to accept multicast traffic. [back to top]
RSVP
- Reservation Protocol. The RSVP protocol is part of a larger effort to enhance the current Internet architecture with support for QoS flows. [back to top]
RTL
- Register Transfer Level. A subset of the Verilog language, which can be automatically turned into gates by a tool like Synopsys. [back to top]
RxNP
- Receive network processor. [back to top]
RxPD
- Receive packet descriptor. [back to top]
RxPM
- Receive packet memory: The primary storage that buffers packets waiting for fabric insertion. The packets come from receive interfaces, from software, or through the recirculation path from TxPM. [back to top]
S
SAM
- Server Attached Module. [back to top]
SAP
- Service Access Point. [back to top]
SAR
- Segmentation And Reassembly. [back to top]
scan
- Scan is a set of registers in a chip, connected in a series, which permits the testing of a chip in the fabrication house, before we buy it. Scan testing finds manufactureing flaws. [back to top]
scheduling
- Local determination of the order in which packets should be sent from outbound queues. [back to top]
SDH
- Synchronous Digital Hierarchy, the European version of SONET. [back to top]
secure shell
- Encrypted transport session used as a secure replacement for Telnet and Trivial File Transfer Protocol (TFTP). [back to top]
SEFS
- Severely Errored Frame Second. [back to top]
segment
- A component of a Label Switched Path (LSP). A label is associated with each segment of an LSP and is carried unchanged over that segment. The label is typically swapped when a packet is switched from one segment to another. [back to top]
sequence number
- A field in the IP packet payload portion used to track the sequence of packets in a flow or stream. The QoS tester sets this value and checks it upon receipt of the packet. [back to top]
server modules
- Each server module in the TSR resides in a module enclosure together with a power conversion card, persisitent file storage, and a pair of solid state disks. Each Server module provides a 300 MHz CPU, 320 Mbytes of memory, and 32Kbytes of NVRAM for maintaining configuration and software images. The server module also supports five 10/100BaseT Ethernet ports and RS-232 coloe port connections. [back to top]
service profile
- Requirements for QoS metrics, availability, method of measurement, and traffic conditioning rules specified in the Service Level Agreement (SLA). [back to top]
SES
- Severely Errored Second. [back to top]
severity level
- A criteria for identifying the nature of a logging event, that also provides a basis for the filtering of logging messages. [back to top]
SFQ
- Stochastic Fair Queue. [back to top]
shaping
- Router/switch device control of packet forwarding rate so that a flow does not exceed the specified service profile. Its primary use is to smooth out burstiness at the expense of incurring delay. It also ensures fairness between flows that share the same IP precedence or DSCP. [back to top]
signaling
- Signaling is a mechanism for an end-system to reserve resources through the network to the destination. Examples are RSVP (for IntServ or TE) and LDP. [back to top]
SLA
- Service Level Agreements. [back to top]
SNMP
- Simple Network Management Protocol. [back to top]
SNTP
- Simple Network Time Protocol. [back to top]
SPF
- Shortest Path First. [back to top]
SPF calculations
- Spanning Tree computations, aim to find the shortest (and presumably fastest) routes through a network from one source to all possible destinations. [back to top]
soft reconfiguration
- A process to generate inbound updates from a neighbor, change and activate BGP policies without taking down the BGP session. [back to top]
SONET line
- The transmission medium between the two points. The remote end of a SONET line is referred to as the line-far-end. [back to top]
SONET path
- The logical connection between the two points on a connection where the SONET frame is assembled (on the sending side) and disassembled (on the receiving side). The remote end of a SONET path is referred to as the path-far-end. [back to top]
SONET section
- Any portion of a SONET connection such as a segment of optical fiber between two repeaters, the repeaters themselves, or a multiplexer. [back to top]
SOP
- Start of Packet. [back to top]
source routing
- When a message is explicitly routed by the source switch to its destination. [back to top]
stub areas
- Areas that do not originate or propagate external routes. [back to top]
subnet mask
- Identifies the number of bits in the 32-bit IP address to be used as the subnet address. [back to top]
subnetting
- Breaks the host portion of a network prefix number into two portions: the subnet number and the host number on that subnet to create an extended network prefix. [back to top]
summarization
- The process of summarizing the subnet routes learned from Internet Gateway Protocol (IGP) into network-level routes. [back to top]
sunrise
- Sunrise is an automated tool for inserting scan chains into a chip design. [back to top]
supernetting
- The practice of extending the classful subnet masks so that a network address and a subnet mask could specify multiple subnets with one address. [back to top]
system
- A programming module with a particular use, such as the "logging system." Each system has a unique system number that is constant across the TSR. [back to top]
T
tail dropping
- Tail dropping is the discard of newly arriving packets when queues are full. [back to top]
TAT
- Theoretical Arrival Time. [back to top]
TDM
- Time Division Multiplexing. A TDM system guarantees each user the predefined transmission rate (bandwidth). It also completely eliminates the interference among users as if there were firewalls installed between them to protect individually-reserved bandwidths. [back to top]
TE
- Traffic Engineering. [back to top]
TE-LSDB
- Traffic engineering link state database, created by IGP from TE modified route advertisements. [back to top]
throughput
- The forwarding rate at which loss first occurs. [back to top]
timestamp
- A field in the payload portion of the IP packet specifying the time a packet was transmitted. The QoS tester sets this value and checks it upon receipt of the packet. [back to top]
TLV
- Type, Length, and Variable used by IS-IS to flood objects to all routers in a given level. [back to top]
ToD
- Time of Day. [back to top]
toroidal fabric
- Each module's physical position in the TSR can be described in terms of its logical spatial coordinates. Currently, this means that each module has a unique <x,y,z> position. The coordinates of a module can be determined algorithmically by knowledge of (1) the coordinates of any one adjacent module and (2) the axis and direction to that adjacent module. The only module that cannot infer its own coordinates is the server attached module, which acts as a "seed" to bring up the other modules.This algorithm will exist on the TSR server ONLY and FRP will be given its module identifier on startup. [back to top]
ToS
- Type of Service. [back to top]
traffic assignment
- Traffic assignment assigns the physical resources used by a packet treatment and associates that packet treatment with an IP precedence classification. [back to top]
traffic classification
- Traffic classification is the grouping of packets into defined classes. [back to top]
traffic engineering
- RFC 2702. A connection-oriented congestion avoidance mechanism using MPLS to override SPF forwarding in order to balance traffic across the network so that links are not over or under utilized. It is possible through policy configuration to direct particular flows through traffic engineered tunnels. [back to top]
trunk
- A trunk is the set of all connections between two nodes. [back to top]
TSR
- Terabit switch router. [back to top]
TTT
- Theoretical Transmission Time. The TTT is based solely on the concept of expected transmission time of a packet in an ideally fair fluid queuing system. [back to top]
TVLV
- Type, Variable Length, and Value. TVLV is a tuple supplied by OSPF to flood objects to all routers in a given area. [back to top]
TxPD
- Transmit Packet Descriptors. [back to top]
U
UART
- Universal Asynchronous Receiver Transmitter. The UART is a device, usually an integrated circuit chip, that performs the parallel-to-serial conversion of digital data to be transmitted. [back to top]
UAS
- Unavailable Second. [back to top]
UNEQ
- Unequipped. [back to top]
UNI
- User to Network Interface. [back to top]
V
VCC
- Virtual Channel Connection. [back to top]
virtual interfaces
- Maintain connectivity of the OSPF backbone area. All routers in the backbone area must be interconnected and virtual links allow the backbone routers to form an adjacency through non-backbone areas. [back to top]
VCI
- Virtual Channel Identifier. The VCI is the address or label of a virtual circuit. [back to top]
VCL
- Virtual Channel Link. [back to top]
Verilog
- Verilog is an HDL programming language for chip design. [back to top]
VPC
- Virtual Path Connection. [back to top]
VPI
- Virtual Path Identifier. [back to top]
W
WDM
- Wave Division Multiplexing. WDM is a way of increasing the capacity of an optical fiber by simultaneously operating at more than one wavelength. [back to top]
weight
- An attribute used to configure preference between routes. Routes with higher weights are preferred. [back to top]
WFQ
- Weighted Fair Queuing. WFQ is a flow-based queuing algorithm that does two things simultaneously: it schedules interactive traffic to the front of the queue to reduce response time, and it fairly shares the remaining bandwidth between high bandwidth flows. WFQ ensures that queues do not starve for bandwidth, and that traffic gets predictable service.