Cisco Cisco IOS Software Release 12.2(27)SBC

affinity bits—An MPLS traffic engineering tunnel’s requirements on the attributes of the links it will 
cross. The tunnel’s affinity bits and affinity mask must match with the attributes of the various links 
carrying the tunnel.

call admission precedence—An MPLS traffic engineering tunnel with a higher priority will, if 
necessary, preempt an MPLS traffic engineering tunnel with a lower priority. An expected use is that 
tunnels that are harder to route will have a higher priority, and can preempt tunnels that are easier to 
route, on the assumption that those lower priority tunnels can find another path.

constraint-based routing—Procedures and protocols used to determine a route across a backbone 
taking into account resource requirements and resource availability, instead of simply using the shortest 
path.

flow—A traffic load entering the backbone at one point—point of presence (POP)—and leaving it from 
another that must be traffic engineered across the backbone. The traffic load will be carried across one 
or more LSP tunnels running from the entry POP to the exit POP.

headend—The LSR at which the tunnel originates. The tunnel’s “head” or tunnel interface will reside 
at this LSR as well.

informs—A type of notification message that is more reliable than a conventional trap notification 
message because an informs message requires acknowledgment.

label—A short, fixed-length data construct that tells switching nodes how to forward data (packets or 
cells).

label-switched path (LSP) tunnel—A configured connection between two routers, using label 
switching to carry the packets. 

LSP—label-switched path. A path that is followed by a labeled packet over several hops, starting at an 
ingress LSR and ending at an egress LSR.

LSR—label switch router. A Layer 3 router that forwards a packet based on the value of a label 
encapsulated in the packet.

MIB—Management Information Base. A database of network management information (consisting of 
MIB objects) that is used and maintained by a network management protocol such as SNMP. The value 
of a MIB object can be changed or retrieved using SNMP commands, usually by a GUI-based network 
management system. MIB objects are organized in a tree structure that includes public (standard) and 
private (proprietary) branches.

MPLS—Multiprotocol Label Switching. Switching method that forwards IP traffic using a label. This 
label instructs the routers and the switches in the network where to forward the packets based on 
preestablished IP routing information. 

notification (see traps)—A message sent by an SNMP agent to a network management station, console, 
or terminal to indicate that a significant event within Cisco IOS software has occurred. 

NMS—network management station. An NMS is a powerful, well-equipped computer (typically an 
engineering workstation) that is used by a network administrator to communicate with other devices in 
the network. An NMS is typically used to manage network resources, gather statistics, and perform a 
variety of network administration and configuration tasks.

OSPF—Open Shortest Path First. A link-state routing protocol used for routing IP.

RSVP—Resource Reservation Protocol. Protocol for reserving network resources to provide quality of 
service (QoS) guarantees to application flows.