RSVP Scalability Enhancements

This document describes the Cisco Resource Reservation Protocol (RSVP) scalability enhancements. It provides an overview of the feature, includes configuration tasks and examples, and lists related Cisco IOS command-line interface (CLI) commands.

Finding Feature Information

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Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to www.cisco.com/​go/​cfn. An account on Cisco.com is not required.

Prerequisites for RSVP Scalability Enhancements

The network must support the following Cisco IOS XE features before the RSVP scalability enhancements are enabled:

  • Resource Reservation Protocol (RSVP)
  • Class-based weighted fair queueing (CBWFQ)

Restrictions for RSVP Scalability Enhancements

  • Sources should not send marked packets without an installed reservation.
  • Sources should not send marked packets that exceed the reserved bandwidth.
  • Sources should not send marked packets to a destination other than the reserved path.

Information About RSVP Scalability Enhancements

RSVP typically performs admission control, classification, policing, and scheduling of data packets on a per-flow basis and keeps a database of information for each flow. RSVP scalability enhancements let you select a resource provider (formerly called a quality of service (QoS) provider) and disable data packet classification so that RSVP performs admission control only. This facilitates integration with service provider (differentiated services (DiffServ)) networks and enables scalability across enterprise networks.

CBWFQ provides the classification, policing, and scheduling functions. CBWFQ puts packets into classes based on the differentiated services code point (DSCP) value in the packet’s Internet Protocol (IP) header, thereby eliminating the need for per-flow state and per-flow processing.

The figure below shows two enterprise networks interconnected through a service provider (SP) network. The SP network has an IP backbone configured as a DiffServ network. Each enterprise network has a voice gateway connected to an SP edge/aggregation router via a wide area network (WAN) link. The enterprise networks are connected to a private branch exchange (PBX).

Figure 1. RSVP/DiffServ Integration Topology

The voice gateways are running classic RSVP, which means RSVP is keeping a state per flow and also classifying, marking, and scheduling packets on a per flow basis. The edge/aggregation routers are running classic RSVP on the interfaces (labeled C and D) connected to the voice gateways and running RSVP for admission control only on the interfaces connected to core routers 1 and 3. The core routers in the DiffServ network are not running RSVP, but are forwarding the RSVP messages to the next hop. The core routers inside the DiffServ network implement a specific per hop behavior (PHB) for a collection of flows that have the same DSCP value.

The voice gateways identify voice data packets and set the appropriate DSCP in their IP headers such that the packets are classified into the priority class in the edge/aggregation routers and in core routers 1, 2, 3 or 1, 4, 3.

The interfaces or the edge/aggregation routers (labeled A and B) connected to core routers 1 and 3 are running RSVP, but are doing admission control only per flow against the RSVP bandwidth pool configured on the DiffServ interfaces of the edge/aggregation routers. CBWFQ is performing the classification, policing, and scheduling functions.

Benefits of RSVP Scalability Enhancements

Enhanced Scalability

RSVP scalability enhancements handle similar flows on a per-class basis instead of a per-flow basis. Since fewer resources are required to maintain per-class QoS guarantees, the RSVP scability enhancements provide faster processing results, thereby enhancing scalability.

Improved Router Performance

RSVP scalability enhancements improve router performance by reducing the cost for data-packet classification and scheduling, which decrease CPU resource consumption. The saved resources can then be used for other network management functions.

How to Configure RSVP Scalability Enhancements

Configuring the Resource Provider


Note

The resource provider was formerly called the QoS provider.

SUMMARY STEPS

    1.    enable

    2.    configure terminal

    3.    interface type slot / subslot / port

    4.    ip rsvp bandwidth [interface-kbps [single-flow-kbps[bc1 kbps | sub-pool kbps]]| percent percent-bandwidth [single-flow-kbps]]

    5.    ip rsvp resource-provider none

    6.    end


DETAILED STEPS
      Command or Action Purpose
    Step 1 enable


    Example: 
    Router> enable
     

    Enables privileged EXEC mode.

    • Enter your password if prompted.
     
    Step 2 configure terminal


    Example: 
    Router# configure terminal
     

    Enters global configuration mode.

     
    Step 3 interface type slot / subslot / port


    Example: 
    Router(config)# interface gigabitEthernet 0/0/0
     

    Configures the interface type and enters interface configuration mode.

     
    Step 4 ip rsvp bandwidth [interface-kbps [single-flow-kbps[bc1 kbps | sub-pool kbps]]| percent percent-bandwidth [single-flow-kbps]]


    Example: 
    Router(config-if)# ip rsvp bandwidth 7500 7500
     

    Enables RSVP on an interface.

    • The optional interface-kbps and single-flow-kbps arguments specify the amount of bandwidth that can be allocated by RSVP flows or to a single flow, respectively. Range is from 1 to 10000000.
    • The optional sub-pooland kbpskeyword and argument specify subpool traffic and the amount of bandwidth that can be allocated by RSVP flows. Range is from 1 to 10000000.
    Note   

    Repeat this command for each interface on which you want to enable RSVP.

    Note   

    The bandwidth that you configure on the interface must match the bandwidth that you configure for the CBWFQ priority queue.

     
    Step 5 ip rsvp resource-provider none


    Example: 
    Router(config-if)# ip rsvp resource-provider none
     

    Sets the resource provider to none.

    Note   

    Setting the resource provider to none instructs RSVP to not associate any resources, such as WFQ queues or bandwidth, with a reservation.

     
    Step 6 end


    Example: 
    Router(config-if)# end
     

    (Optional) Returns to privileged EXEC mode.

     

    Disabling Data Packet Classification

    Perform the following task to disable data packet classification. Disabling data packet classification instructs RSVP not to process every packet, but to perform admission control only.

    SUMMARY STEPS

      1.    enable

      2.    configure terminal

      3.    interface type slot / subslot / port

      4.    ip rsvp data-packet classification none

      5.    end


    DETAILED STEPS
        Command or Action Purpose
      Step 1 enable


      Example: 
      Router> enable
       

      Enables privileged EXEC mode.

      • Enter your password if prompted.
       
      Step 2 configure terminal


      Example: 
      Router# configure terminal
       

      Enters global configuration mode.

       
      Step 3 interface type slot / subslot / port


      Example: 
      Router(config)# interface gigabitEthernet0/0/0
       

      Configures the interface type and enters interface configuration mode.

       
      Step 4 ip rsvp data-packet classification none


      Example: 
      Router(config-if)# ip rsvp data-packet classification none
       

      Disables data packet classification.

       
      Step 5 end


      Example: 
      Router(config-if)# end
       

      (Optional) Returns to privileged EXEC mode.

       

      Configuring Class Maps and Policy Maps

      SUMMARY STEPS

        1.    enable

        2.    configure terminal

        3.    class-map class-map-name

        4.    exit

        5.    policy-map policy-map-name

        6.    end


      DETAILED STEPS
          Command or Action Purpose
        Step 1 enable


        Example: 
        Router> enable
         

        Enables privileged EXEC mode.

        • Enter your password if prompted.
         
        Step 2 configure terminal


        Example: 
        Router# configure terminal
         

        Enters global configuration mode.

         
        Step 3 class-map class-map-name


        Example: 
        Router(config)# class-map class1
         

        Specifies the name of the class for which you want to create or modify class-map match criteria and enters the class map configuration mode.

         
        Step 4 exit


        Example: 
        Router(config-cmap)# exit
         

        Returns to the global configuration mode.

         
        Step 5 policy-map policy-map-name


        Example: 
        Router(config)# policy-map policy1
         

        Specifies the name of the policy map to be created, added to, or modified before you can configure policies for classes whose match criteria are defined in a class map.

         
        Step 6 end


        Example: 
        Router(config-control-policymap)# end
         

        (Optional) Returns to privileged EXEC mode.

         

        Attaching a Policy Map to an Interface

        Perform the following task to attach a policy map to an interface. If at the time you configure the RSVP scalability enhancements, there are existing reservations that use classic RSVP, no additional marking, classification, or scheduling is provided for these flows. You can also delete these reservations after you configure the RSVP scalability enhancements.

        SUMMARY STEPS

          1.    enable

          2.    configure terminal

          3.    interface type slot / subslot / port

          4.    service-policy {input | output} policy-map-name

          5.    end


        DETAILED STEPS
            Command or Action Purpose
          Step 1 enable


          Example: 
          Router> enable
           

          Enables privileged EXEC mode.

          • Enter your password if prompted.
           
          Step 2 configure terminal


          Example: 
          Router# configure terminal
           

          Enters global configuration mode.

           
          Step 3 interface type slot / subslot / port


          Example: 
          Router(config)# interface gigabitEthernet 0/0/0
           

          Configures the interface type and enters interface configuration mode.

           
          Step 4 service-policy {input | output} policy-map-name


          Example: 
          Router(config-if)# service-policy input policy1
           

          Attaches a single policy map to one or more interfaces to specify the service policy for those interfaces.

           
          Step 5 end


          Example: 
          Router(config-if)# end
           

          (Optional) Returns to privileged EXEC mode.

           

          Verifying RSVP Scalability Enhancements Configuration

          SUMMARY STEPS

            1.    Enter the show ip rsvp interface detailcommand to display information about interfaces, subinterfaces, resource providers, and data packet classification. The output in the following example shows that the ATM interface 6/0 has resource provider none configured and that data packet classification is turned off:

            2.    Enter the show ip rsvp installed detailcommand to display information about interfaces, subinterfaces, their admitted reservations, bandwidth, resource providers, and data packet classification.

            3.    Wait for a while, then enter the show ip rsvp installed detailcommand again. In the following output, notice there is no increment in the number of packets classified:


          DETAILED STEPS
            Step 1   Enter the show ip rsvp interface detailcommand to display information about interfaces, subinterfaces, resource providers, and data packet classification. The output in the following example shows that the ATM interface 6/0 has resource provider none configured and that data packet classification is turned off:

            Example: 
            Router# show ip rsvp interface detail
 AT6/0:
   Bandwidth:
     Curr allocated: 190K bits/sec
     Max. allowed (total): 112320K bits/sec
     Max. allowed (per flow): 112320K bits/sec
   Neighbors:
     Using IP encap: 1.  Using UDP encaps: 0
   DSCP value used in Path/Resv msgs: 0x30
   RSVP Data Packet Classification is OFF
   RSVP resource provider is: none
            Note   

            The last two lines in the preceding output verify that the RSVP scalability enhancements (disabled data packet classification and resource provider none) are present.
            Step 2   Enter the show ip rsvp installed detailcommand to display information about interfaces, subinterfaces, their admitted reservations, bandwidth, resource providers, and data packet classification.

            Example: 
            Router# show ip rsvp installed detail
RSVP: GigabitEthernet0/0/0 has no installed reservations
RSVP: ATM6/0 has the following installed reservations
RSVP Reservation. Destination is 10.20.20.212, Source is 10.10.10.211, 
  Protocol is UDP, Destination port is 14, Source port is 14
  Reserved bandwidth: 50K bits/sec, Maximum burst: 1K bytes, Peak rate: 50K bits/sec
  Min Policed Unit: 0 bytes, Max Pkt Size: 1514 bytes
  Resource provider for this flow: None
  Conversation supports 1 reservations
  Data given reserved service: 0 packets (0 bytes)
  Data given best-effort service: 0 packets (0 bytes)
  Reserved traffic classified for 54 seconds
  Long-term average bitrate (bits/sec): 0M reserved, 0M best-effort
RSVP Reservation. Destination is 10.20.20.212, Source is 10.10.10.211, 
  Protocol is UDP, Destination port is 10, Source port is 10
  Reserved bandwidth: 20K bits/sec, Maximum burst: 1K bytes, Peak rate: 20K bits/sec
  Min Policed Unit: 0 bytes, Max Pkt Size: 1514 bytes
  Resource provider for this flow: None
  Conversation supports 1 reservations
  Data given reserved service: 0 packets (0 bytes)
  Data given best-effort service: 0 packets (0 bytes)
  Reserved traffic classified for 80 seconds
  Long-term average bitrate (bits/sec): 0M reserved, 0M best-effort
            Step 3   Wait for a while, then enter the show ip rsvp installed detailcommand again. In the following output, notice there is no increment in the number of packets classified:

            Example: 
            Router# show ip rsvp installed detail
RSVP: Ethernet3/3 has no installed reservations
RSVP: ATM6/0 has the following installed reservations
RSVP Reservation. Destination is 10.20.20.212, Source is 10.10.10.211, 
  Protocol is UDP, Destination port is 14, Source port is 14
  Reserved bandwidth: 50K bits/sec, Maximum burst: 1K bytes, Peak rate: 50K bits/sec
  Min Policed Unit: 0 bytes, Max Pkt Size: 1514 bytes
  Resource provider for this flow: None
  Conversation supports 1 reservations
  Data given reserved service: 0 packets (0 bytes)
  Data given best-effort service: 0 packets (0 bytes)
  Reserved traffic classified for 60 seconds
  Long-term average bitrate (bits/sec): 0 reserved, OM best-effort
RSVP Reservation. Destination is 10.20.20.212, Source is 10.10.10.211, 
  Protocol is UDP, Destination port is 10, Source port is 10
  Reserved bandwidth: 20K bits/sec, Maximum burst: 1K bytes, Peak rate: 20K bits/sec
  Min Policed Unit: 0 bytes, Max Pkt Size: 1514 bytes
  Resource provider for this flow: None
  Conversation supports 1 reservations
  Data given reserved service: 0 packets (0 bytes)
  Data given best-effort service: 0 packets (0 bytes)
  Reserved traffic classified for 86 seconds
  Long-term average bitrate (bits/sec): OM reserved, 0M best-effort

            Monitoring and Maintaining RSVP Scalability Enhancements

            To monitor and maintain RSVP scalability enhancements, use the following commands in EXEC mode. The following commands can be entered in any order.

            Command

            Purpose

            		 
            Router# show ip rsvp installed

            Displays information about interfaces and their admitted reservations.

            		 
            Router# show ip rsvp installed detail

            Displays additional information about interfaces and their admitted reservations.

            		 
            Router# show ip rsvp interface

            Displays RSVP-related interface information.

            		 
            Router# show ip rsvp interface detail

            Displays additional RSVP-related interface information.

            		 
            Router# show queueing [custom | fair | priority | random-detect [interface serial-number]]

            Displays all or selected configured queueing strategies and available bandwidth for RSVP reservations.

            Configuration Examples for RSVP Scalability Enhancements

            Examples Configuring the Resource Provider as None with Data Classification Turned Off

            Following is output from the showiprsvpinterfacedetail command before a resource provider is configured as none and data-packet classification is turned off:

            Router# show ip rsvp interface detail
 AT6/0:
   Bandwidth:
     Curr allocated: 190K bits/sec
     Max. allowed (total): 112320K bits/sec
     Max. allowed (per flow): 112320K bits/sec
   Neighbors:
     Using IP encap: 1.  Using UDP encaps: 0
   DSCP value used in Path/Resv msgs: 0x30

            Following is the output from the showqueueingcommand before a resource provider is configured as none and data packet classification is turned off:

            Router# show queueing int atm6/0
  Interface ATM6/0 VC 200/100 
  Queueing strategy: weighted fair
  Output queue: 63/512/64/3950945 (size/max total/threshold/drops)
     Conversations  2/5/64 (active/max active/max total)
     Reserved Conversations 0/0 (allocated/max allocated)
     Available Bandwidth 450 kilobits/sec

            Note

            New reservations do not reduce the available bandwidth (450 kilobits/sec shown above). Instead RSVP performs admission control only using the bandwidth limit configured in the iprsvpbandwidth command. The bandwidth configured in this command should match the bandwidth configured in the CBWFQ class that you set up to handle the reserved traffic.

            The following example shows how to configure resource provider as none: 

            Router# configure terminal
Enter configuration commands, one per line.  End with CNTL/Z.
Router(config)# interface atm6/0
Router(config-if)# ip rsvp resource-provider none
 
Router(config-if)# end
Router#

            The following example shows how to turn off the data packet classification: 

            Router# configure terminal
Enter configuration commands, one per line.  End with CNTL/Z.
Router(config)# interface atm6/0
Router(config-if)# ip rsvp data-packet classification none
 
Router(config-if)# end

            Following is the output from the showiprsvpinterfacedetail command after resource provider has been configured as none and data packet classification has been turned off:

            Router# show ip rsvp interface detail
 AT6/0:
   Bandwidth:
     Curr allocated: 190K bits/sec
     Max. allowed (total): 112320K bits/sec
     Max. allowed (per flow): 112320K bits/sec
   Neighbors:
     Using IP encap: 1.  Using UDP encaps: 0
   DSCP value used in Path/Resv msgs: 0x30
   RSVP Data Packet Classification is OFF
   RSVP resource provider is: none

            The following output from the showiprsvpinstalleddetail command verifies that resource provider none is configured and data packet classification is turned off:

            Router# show ip rsvp installed detail
RSVP: ATM6/0 has the following installed reservations
RSVP Reservation. Destination is 10.20.20.212, Source is 10.10.10.211, 
  Protocol is UDP, Destination port is 14, Source port is 14
  Reserved bandwidth: 50K bits/sec, Maximum burst: 1K bytes, Peak rate: 50K bits/sec
  Min Policed Unit: 0 bytes, Max Pkt Size: 1514 bytes
  Resource provider for this flow: None
  Conversation supports 1 reservations
  Data given reserved service: 3192 packets (1557696 bytes)
  Data given best-effort service: 42 packets (20496 bytes)
  Reserved traffic classified for 271 seconds
  Long-term average bitrate (bits/sec): 45880 reserved, 603 best-effort
RSVP Reservation. Destination is 10.20.20.212, Source is 10.10.10.211, 
  Protocol is UDP, Destination port is 10, Source port is 10
  Reserved bandwidth: 20K bits/sec, Maximum burst: 1K bytes, Peak rate: 20K bits/sec
  Min Policed Unit: 0 bytes, Max Pkt Size: 1514 bytes
  Resource provider for this flow: None
  Conversation supports 1 reservations
  Data given reserved service: 1348 packets (657824 bytes)
  Data given best-effort service: 0 packets (0 bytes)
  Reserved traffic classified for 296 seconds
  Long-term average bitrate (bits/sec): 17755 reserved, 0M best-effort

            The following output shows no increments in packet counts after the source sends data packets that match the reservation:

            Router# show ip rsvp installed detail
RSVP: GigabitEthernet3/3 has no installed reservations
RSVP: ATM6/0 has the following installed reservations
RSVP Reservation. Destination is 10.20.20.212, Source is 10.10.10.211,
  Protocol is UDP, Destination port is 14, Source port is 14
  Reserved bandwidth: 50K bits/sec, Maximum burst: 1K bytes, Peak rate: 50K bits/sec
  Min Policed Unit: 0 bytes, Max Pkt Size: 1514 bytes
  Resource provider for this flow: None
  Conversation supports 1 reservations
  Data given reserved service: 3192 packets (1557696 bytes)
  Data given best-effort service: 42 packets (20496 bytes)
  Reserved traffic classified for 282 seconds
  Long-term average bitrate (bits/sec): 44051 reserved, 579 best-effort
RSVP Reservation. Destination is 145.20.20.212, Source is 145.10.10.211, 
  Protocol is UDP, Destination port is 10, Source port is 10
  Reserved bandwidth: 20K bits/sec, Maximum burst: 1K bytes, Peak rate: 20K bits/sec
  Min Policed Unit: 0 bytes, Max Pkt Size: 1514 bytes
  Resource provider for this flow: None
  Conversation supports 1 reservations
  Data given reserved service: 1348 packets (657824 bytes)
  Data given best-effort service: 0 packets (0 bytes)
  Reserved traffic classified for 307 seconds
  Long-term average bitrate (bits/sec): 17121 reserved, 0M best-effort

            The following output verifies that data packet classification is occurring:

            Router# show ip rsvp installed detail
Enter configuration commands, one per line.  End with CNTL/Z.
RSVP: ATM6/0 has the following installed reservations
RSVP Reservation. Destination is 10.20.20.212, Source is 10.10.10.211, 
  Protocol is UDP, Destination port is 14, Source port is 14
  Reserved bandwidth: 50K bits/sec, Maximum burst: 1K bytes, Peak rate: 50K bits/sec
  Min Policed Unit: 0 bytes, Max Pkt Size: 1514 bytes
  Resource provider for this flow: None
  Conversation supports 1 reservations
  Data given reserved service: 3683 packets (1797304 bytes)
  Data given best-effort service: 47 packets (22936 bytes)
  Reserved traffic classified for 340 seconds
  Long-term average bitrate (bits/sec): 42201 reserved, 538 best-effort
RSVP Reservation. Destination is 10.20.20.212, Source is 10.10.10.211, 
  Protocol is UDP, Destination port is 10, Source port is 10
  Reserved bandwidth: 20K bits/sec, Maximum burst: 1K bytes, Peak rate: 20K bits/sec
  Min Policed Unit: 0 bytes, Max Pkt Size: 1514 bytes
  Resource provider for this flow: None
  Conversation supports 1 reservations
  Data given reserved service: 1556 packets (759328 bytes)
  Data given best-effort service: 0 packets (0 bytes)
  Reserved traffic classified for 364 seconds
  Long-term average bitrate (bits/sec): 16643 reserved, 0M best-effort

            Note

            You can use debugiprsvptraffic-control and debugiprsvpwfq simultaneously. Use theshowdebug command to see which debugging commands are enabled.

            Additional References

            The following sections provide references related to the RSVP Scalability Enhancements feature.

            Related Documents

            Related Topic

            Document Title

            Cisco IOS commands

            Cisco IOS Master Commands List, All Releases

            QoS commands: complete command syntax, command modes, command history, defaults, usage guidelines, and examples

            Cisco IOS Quality of Service Solutions Command Reference

            QoS configuration tasks related to RSVP

            "Configuring RSVP" module

            Standards

            Standard

            Title

            No new or modified standards are supported by this feature, and support for existing standards has not been modified by this feature.

            --

            MIBs

            MIB

            MIBs Link

            None

            To locate and download MIBs for selected platforms, software releases, and feature sets, use Cisco MIB Locator found at the following URL:

            http:/​/​www.cisco.com/​go/​mibs

            RFCs

            RFC

            Title

            RFC 2205

            Resource Reservation Protocol

            RFC 2206

            RSVP Management Information Base using SMIv2

            Technical Assistance

            Description

            Link

            The Cisco Support and Documentation website provides online resources to download documentation, software, and tools. Use these resources to install and configure the software and to troubleshoot and resolve technical issues with Cisco products and technologies. Access to most tools on the Cisco Support and Documentation website requires a Cisco.com user ID and password.

            http:/​/​www.cisco.com/​cisco/​web/​support/​index.html

            Feature Information for RSVP Scalability Enhancements

            The following table provides release information about the feature or features described in this module. This table lists only the software release that introduced support for a given feature in a given software release train. Unless noted otherwise, subsequent releases of that software release train also support that feature.

            Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to www.cisco.com/​go/​cfn. An account on Cisco.com is not required.

            Table 1 Feature Information for RSVP Scalability Enhancements

            Feature Name

            Releases

            Feature Information

            RSVP Scalability Enhancements

            Cisco IOS XE Release 2.6

            Cisco IOS XE Release 3.8S

            RSVP scalability enhancements let you select a resource provider (formerly called a QoS provider) and disable data packet classification so that RSVP performs admission control only. This facilitates integration with service provider (DiffServ) networks and enables scalability across enterprise networks.

            The following commands were introduced or modified: debug ip rsvp traffic-control, debug ip rsvp wfq, ip rsvp data-packet classification none, ip rsvp resource-provider, show ip rsvp installed, show ip rsvp interface, show queueing.

            In Cisco IOS XE Release 3.8S, support was added for the Cisco ASR 903 Router.

            Glossary

            admission control --The process by which an RSVP reservation is accepted or rejected based on end-to-end available network resources.

            aggregate --A collection of packets with the same DSCP.

            bandwidth --The difference between the highest and lowest frequencies available for network signals. This term also describes the rated throughput capacity of a given network medium or protocol.

            CBWFQ -- class-based weighted fair queueing. A queueing mechanism that extends the standard WFQ functionality to provide support for user-defined traffic classes.

            DiffServ --differentiated services. An architecture based on a simple model where traffic entering a network is classified and possibly conditioned at the boundaries of the network. The class of traffic is then identified with a DS code point or bit marking in the IP header. Within the core of the network, packets are forwarded according to the per-hop behavior associated with the DS code point.

            DSCP --differentiated services code point. The six most significant bits of the 1-byte IP type of service (ToS) field. The per-hop behavior represented by a particular DSCP value is configurable. DSCP values range between 0 and 63.

            enterprise network --A large and diverse network connecting most major points in a company or other organization.

            flow --A stream of data traveling between two endpoints across a network (for example, from one LAN station to another). Multiple flows can be transmitted on a single circuit.

            packet --A logical grouping of information that includes a header containing control information and (usually) user data. Packets most often refer to network-layer units of data.

            PBX --private branch exchange. A digital or analog telephone switchboard located on the subscriber premises and used to connect private and public telephone networks.

            PHB --per-hop behavior. A DiffServ concept that specifies how specifically marked packets are to be treated by each DiffServ router.

            QoS --quality of service. A measure of performance for a transmission system that reflects its transmission quality and service availability.

            RSVP --Resource Reservation Protocol. A protocol for reserving network resources to provide quality of service guarantees to application flows.

            Voice over IP --See VoIP.

            VoIP --Voice over IP. The ability to carry normal telephony-style voice over an IP-based internet maintaining telephone-like functionality, reliability, and voice quality.

            WFQ --weighted fair queueing. A queue management algorithm that provides a certain fraction of link bandwidth to each of several queues, based on the relative bandwidth applied to each of the queues.