APPENDIX D. Glossary

• Admission control

  A traffic control function that decides whether the packet scheduler in the node can supply the requested QoS while continuing to provide the QoS requested by previously-admitted requests. See also "policy control" and "traffic control".

• Adspec

  An Adspec is a data element (object) in a Path message that carries a package of OPWA advertising information. See "OPWA".

• Auto-refresh loop

  An auto-refresh loop is an error condition that occurs when a topological loop of routers continues to refresh existing reservation state even though all receivers have stopped requesting these reservations. See section 3.4 for more information.

• Blockade state

  Blockade state helps to solve a "killer reservation" problem. See sections 2.5 and 3.5, and "killer reservation".

• Branch policing

  Traffic policing at a multicast branching point on an outgoing interface that has "less" resources reserved than another outgoing interface for the same flow. See "traffic policing".

• C-Type

  The class type of an object; unique within class-name. See "class-name".

• Class-name

  The class of an object. See "object".

• DestAddress

  The IP destination address; part of session identification. See "session".

• Distinct style

  A (reservation) style attribute; separate resources are reserved for each different sender. See also "shared style".

• Downstream

  Towards the data receiver(s).

• DstPort

  The IP (generalized) destination port used as part of a session. See "generalized destination port".

• Entry policing

  Traffic policing done at the first RSVP- (and policing-) capable router on a data path.

• ERROR_SPEC

  Object that carries the error report in a PathErr or ResvErr message.

• Explicit sender selection

  A (reservation) style attribute; all reserved senders are to be listed explicitly in the reservation message. See also "wildcard sender selection".

• FF style

  Fixed Filter reservation style, which has explicit sender selection and distinct attributes.

• FilterSpec

  Together with the session information, defines the set of data packets to receive the QoS specified in a flowspec. The filterspec is used to set parameters in the packet classifier function. A filterspec may be carried in a FILTER_SPEC or SENDER_TEMPLATE object.

• Flow descriptor

  The combination of a flowspec and a filterspec.

• Flowspec

  Defines the QoS to be provided for a flow. The flowspec is used to set parameters in the packet scheduling function to provide the requested quality of service. A flowspec is carried in a FLOWSPEC object. The flowspec format is opaque to RSVP and is defined by the Integrated Services Working Group.

• Generalized destination port

  The component of a session definition that provides further transport or application protocol layer demultiplexing beyond DestAddress. See "session".

• Generalized source port

  The component of a filter spec that provides further transport or application protocol layer demultiplexing beyond the sender address.

• GLB

  Greatest Lower Bound

• Incoming interface

  The interface on which data packets are expected to arrive, and on which Resv messages are sent.

• INTEGRITY

  Object of an RSVP control message that contains cryptographic data to authenticate the originating node and to verify the contents of an RSVP message.

• Killer reservation problem

  The killer reservation problem describes a case where a receiver attempting and failing to make a large QoS reservation prevents smaller QoS reservations from being established. See Sections 2.5 and 3.5 for more information.

• LIH

  The LIH (Logical Interface Handle) is used to help deal with non-RSVP clouds. See Section 2.9 for more information.

• Local repair

  Allows RSVP to rapidly adapt its reservations to changes in routing. See Section 3.6 for more information.

• LPM

  Local Policy Module. the function that exerts policy control.

• LUB

  Least Upper Bound.

• Merge policing

  Traffic policing that takes place at data merge point of a shared reservation.

• Merging

  The process of taking the maximum (or more generally the least upper bound) of the reservations arriving on outgoing interfaces, and forwarding this maximum on the incoming interface. See Section 2.2 for more information.

• MTU

  Maximum Transmission Unit.

• Next hop

  The next router in the direction of traffic flow.

• NHOP

  An object that carries the Next Hop information in RSVP control messages.

• Node

  A router or host system.

• Non-RSVP clouds

  Groups of hosts and routers that do not run RSVP. Dealing with nodes that do not support RSVP is important for backwards compatibility. See section 2.9.

• Object

  An element of an RSVP control message; a type, length, value triplet.

• OPWA

  Abbreviation for "One Pass With Advertising". Describes a reservation setup model in which (Path) messages sent downstream gather information that the receiver(s) can use to predict the end-to-end service. The information that is gathered is called an advertisement. See also "Adspec".

• Outgoing interface

  Interface through which data packets and Path messages are forwarded.

• Packet classifier

  Traffic control function in the primary data packet forwarding path that selects a service class for each packet, in accordance with the reservation state set up by RSVP. The packet classifier may be combined with the routing function. See also "traffic control".

• Packet scheduler

  Traffic control function in the primary data packet forwarding path that implements QoS for each flow, using one of the service models defined by the Integrated Services Working Group. See also " traffic control".

• Path state

  Information kept in routers and hosts about all RSVP senders.

• PathErr

  Path Error RSVP control message.

• PathTear

  Path Teardown RSVP control message.

• PHOP

  An object that carries the Previous Hop information in RSVP control messages.

• Police

  See traffic policing.

• Policy control

  A function that determines whether a new request for quality of service has administrative permission to make the requested reservation. Policy control may also perform accounting (usage feedback) for a reservation.

• Policy data

  Data carried in a Path or Resv message and used as input to policy control to determine authorization and/or usage feedback for the given flow.

• Previous hop

  The previous router in the direction of traffic flow. Resv messages flow towards previous hops.

• ProtocolId

  The component of session identification that specifies the IP protocol number used by the data stream.

• QoS

  Quality of Service.

• Reservation state

  Information kept in RSVP-capable nodes about successful RSVP reservation requests.

• Reservation style

  Describes a set of attributes for a reservation, including the sharing attributes and sender selection attributes. See Section 1.3 for details.

• Resv message

  Reservation request RSVP control message.

• ResvConf

  Reservation Confirmation RSVP control message, confirms successful installation of a reservation at some upstream node.

• ResvErr

  Reservation Error control message, indicates that a reservation request has failed or an active reservation has been preempted.

• ResvTear

  Reservation Teardown RSVP control message, deletes reservation state.

• Rspec

  The component of a flowspec that defines a desired QoS. The Rspec format is opaque to RSVP and is defined by the Integrated Services Working Group of the IETF.

• RSVP_HOP

  Object of an RSVP control message that carries the PHOP or NHOP address of the source of the message.

• Scope

  The set of sender hosts to which a given reservation request is to be propagated.

• SE style

  Shared Explicit reservation style, which has explicit sender selection and shared attributes.

• Semantic fragmentation

  A method of fragmenting a large RSVP message using information about the structure and contents of the message, so that each fragment is a logically complete RSVP message.

• Sender template

  Parameter in a Path message that defines a sender; carried in a SENDER_TEMPLATE object. It has the form of a filter spec that can be used to select this sender's packets from other packets in the same session on the same link.

• Sender Tspec

  Parameter in a Path message, a Tspec that characterizes the traffic parameters for the data flow from the corresponding sender. It is carried in a SENDER_TSPEC object.

• Session

  An RSVP session defines one simplex unicast or multicast data flow for which reservations are required. A session is identified by the destination address, transport-layer protocol, and an optional (generalized) destination port.

• Shared style

  A (reservation) style attribute: all reserved senders share the same reserved resources. See also "distinct style".

• Soft state

  Control state in hosts and routers that will expire if not refreshed within a specified amount of time.

• STYLE

  Object of an RSVP message that specifies the desired reservation style.

• Style

  See "reservation style"

• TIME_VALUES

  Object in an RSVP control message that specifies the time period timer used for refreshing the state in this message.

• Traffic control

  The entire set of machinery in the node that supplies requested QoS to data streams. Traffic control includes packet classifier, packet scheduler, and admission control functions.

• Traffic policing

  The function, performed by traffic control, of forcing a given data flow into compliance with the traffic parameters implied by the reservation. It may involve dropping non-compliant packets or sending them with lower priority, for example.

• TSpec

  A traffic parameter set that describes a flow. The format of a Tspec is opaque to RSVP and is defined by the Integrated Service Working Group.

• UDP encapsulation

  A way for hosts that cannot use raw sockets to participate in RSVP by encapsulating the RSVP protocol (raw) packets in ordinary UDP packets. See Section APPENDIX C for more information.

• Upstream

  Towards the traffic source. RSVP Resv messages flow upstream.

• WF style

  Wildcard Filter reservation style, which has wildcard sender selection and shared attributes.

• Wildcard sender selection

  A (reservation) style attribute: traffic from any sender to a specific session receives the same QoS. See also "explicit sender selection".