Configuring RSVP (REMOVED)
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Table Of Contents
Planning for RSVP Configuration
RSVP Implementation Considerations
Resource Reservation Protocol Configuration Task List
Entering Senders in the RSVP Database
Entering Receivers in the RSVP Database
Specifying Multicast Destinations
Controlling Which RSVP Neighbor Can Offer a Reservation
Enabling RSVP to Attach to NetFlow
Setting the IP Precedence and ToS Values
RSVP Configuration for a Multicast Session Example
Feature Information for Configuring RSVP
Configuring RSVP
This chapter describes the tasks for configuring the Resource Reservation Protocol (RSVP) feature, which is an IP service that allows end systems or hosts on either side of a router network to establish a reserved-bandwidth path between them to predetermine and ensure QoS for their data transmission.
For a complete description of the RSVP commands in this module, see the Cisco IOS Quality of Service Solutions Command Reference. To locate documentation of other commands that appear in this chapter, use the command reference master index or search online.
Finding Feature Information
For the latest feature information and caveats, see the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the "Feature Information for Configuring RSVP" section.
Use Cisco Feature Navigator to find information about platform support and Cisco IOS, Catalyst OS, and Cisco IOS XE software image support. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not required.
RSVP Functionality
RSVP allows end systems to request QoS guarantees from the network. The need for network resource reservations differs for data traffic versus for real-time traffic, as follows:
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Data traffic seldom needs reserved bandwidth because internetworks provide datagram services for data traffic. This asynchronous packet switching may not need guarantees of service quality. End-to-end controls between data traffic senders and receivers help ensure adequate transmission of bursts of information.
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Data applications, with little need for resource guarantees, frequently demand relatively lower bandwidth than real-time traffic. The almost constant high bit-rate demands of a video conference application and the bursty low bit-rate demands of an interactive data application share available network resources.
RSVP prevents the demands of traffic such as large file transfers from impairing the bandwidth resources necessary for bursty data traffic. When RSVP is used, the routers sort and prioritize packets much like a statistical time-division multiplexer (TDM) would sort and prioritize several signal sources that share a single channel.
RSVP mechanisms enable real-time traffic to reserve resources necessary for consistent latency. A video conferencing application can use settings in the router to propagate a request for a path with the required bandwidth and delay for video conferencing destinations. RSVP will check and repeat reservations at regular intervals. By this process, RSVP can adjust and alter the path between RSVP end systems to recover from route changes.
Real-time traffic (unlike data traffic) requires a guaranteed network consistency. Without consistent QoS, real-time traffic faces the following problems:
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RSVP works in conjunction with weighted fair queueing (WFQ) or Random Early Detection (RED). This conjunction of reservation setting with packet queueing uses two key concepts: end-to-end flows with RSVP and router-to-router conversations with WFQ:
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RSVP allows for hosts to send packets to a subset of all hosts (multicasting). RSVP assumes that resource reservation applies primarily to multicast applications (such as video conferencing). Although the primary target for RSVP is multimedia traffic, a clear interest exists for the reservation of bandwidth for unicast traffic (such as Network File System (NFS) and virtual private network management). A unicast transmission involves a host sending packets to a single host.
For more information about RSVP, see the "Signalling Overview" module.
RSVP Reservation Types
These are the two types of multicast flows:
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RSVP describes these reservations as having certain algorithmic attributes.
Distinct Reservation
An example of a distinct reservation is a video application in which each sender emits a distinct data stream that requires admission and management in a queue. Such a flow, therefore, requires a separate reservation per sender on each transmission facility it crosses (such as Ethernet, a High-Level Data Link Control (HDLC) line, a Frame Relay data-link connection identifier (DLCI), or an ATM virtual channel). RSVP refers to this distinct reservation as explicit and installs it using a Fixed Filter style of reservation.
Use of RSVP for unicast applications is generally a degenerate case of a distinct flow.
Shared Reservation
An example of a shared reservation also is an audio application in which each sender emits a distinct data stream that requires admission and management in a queue. However, because of the nature of the application, a limited number of senders are sending data at any given time. Such a flow, therefore, does not require a separate reservation per sender. Instead, it uses a single reservation that can be applied to any sender within a set as needed.
RSVP installs a shared reservation using a Wild Card or Shared Explicit style of reservation, with the difference between the two determined by the scope of application (which is either wild or explicit):
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Planning for RSVP Configuration
You must plan carefully to successfully configure and use RSVP on your network. At a minimum, RSVP must reflect your assessment of bandwidth needs on router interfaces. Consider the following questions as you plan for RSVP configuration:
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RSVP Implementation Considerations
You should be aware of RSVP implementation considerations as you design your reservation system. RSVP does not model all data links likely to be present on the internetwork. RSVP models an interface as having a queueing system that completely determines the mix of traffic on the interface; bandwidth or delay characteristics are only deterministic to the extent that this model holds. Unfortunately, data links are often imperfectly modeled this way. Use the following guidelines:
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Resource Reservation Protocol Configuration Task List
After you have planned your RSVP configuration, enter the Cisco IOS commands that implement your configuration plan. To configure RSVP, perform the tasks described in the following sections. The task in the first section is required; the tasks in the remaining sections are optional.
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Enabling RSVP
By default, RSPV is disabled so that it is backward compatible with systems that do not implement RSVP. To enable RSVP for IP on an interface, use the following command in interface configuration mode:
Router(config-if)# ip rsvp bandwidth [interface-kbps] [single-flow-kbps]
Enables RSVP for IP on an interface.
This command starts RSVP and sets the bandwidth and single-flow limits. The default maximum bandwidth is up to 75 percent of the bandwidth available on the interface. By default, the amount reservable by a flow can be up to the entire reservable bandwidth.
Reservations on individual circuits that do not exceed 100 kbps normally succeed. If, however, reservations have been made on other circuits adding up to 1.2 Mbps, and a reservation is made on a subinterface that itself has enough remaining bandwidth, the reservation request will still be refused because the physical interface lacks supporting bandwidth.
Entering Senders in the RSVP Database
You can configure the router to behave as though it is periodically receiving an RSVP PATH message from the sender or previous hop routes containing the indicated attributes. To enter senders in the RSVP database, use the following command in global configuration mode:
The related ip rsvp sender-host command enables a router to simulate a host generating RSVP PATH messages. It is used mostly for debugging and testing purposes.
Entering Receivers in the RSVP Database
You can configure the router to behave as though it is continuously receiving an RSVP RESV message from the originator containing the indicated attributes. To enter receivers in the RSVP database, use the following command in global configuration mode:
The related ip rsvp reservation-host command enables a router to simulate a host generating RSVP RESV messages. It is used mostly for debugging and testing purposes.
Specifying Multicast Destinations
Question for reviewers-----Is this supported?
If RSVP neighbors are discovered to be using User Datagram Protocol (UDP) encapsulation, the router will automatically generate UDP-encapsulated messages for consumption by the neighbors.
However, in some cases, a host will not originate such a message until it has first heard from the router, which it can only do via UDP. You must instruct the router to generate UDP-encapsulated RSVP multicasts whenever it generates an IP-encapsulated multicast.
To specify multicast destinations that should receive UDP-encapsulated messages, use the following command in global configuration mode:
Router(config)# ip rsvp udp-multicasts [multicast-address]
Specifies multicast destinations that should receive UDP-encapsulated messages.
Controlling Which RSVP Neighbor Can Offer a Reservation
By default, any RSVP neighbor may offer a reservation request. To control which RSVP neighbors can offer a reservation request, use the following command in global configuration mode:
Router(config)# ip rsvp neighbor access-list-number
Limits which routers may offer reservations.
When this command is configured, only neighbors conforming to the access list are accepted. The access list is applied to the IP header.
Enabling RSVP to Attach to NetFlow
Question for reviewers-----Is this supported?
To enable RSVP to attach itself to NetFlow so that it can receive information about packets in order to update its token bucket and set IP precedence as required, use the following command in interface configuration mode:
This task is optional for the following reason: When the interface is configured with the ip rsvp svc-required command to use ATM switched virtual circuits (SVCs), RSVP automatically attaches itself to NetFlow to perform packet flow identification (in which case you need not perform this task). However, if you want to perform IP Precedence-type of service (ToS) bit setting in every packet without using ATM SVCs, then you must use the ip rsvp flow-assist command to instruct RSVP to attach itself to NetFlow.
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Setting the IP Precedence and ToS Values
To configure the IP Precedence and ToS values to be used to mark packets in an RSVP reserved path that either conform to or exceed the RSVP flow specification (flowspec), use the following commands in interface configuration mode:
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The ToS byte in the IP header defines the three high-order bits as IP Precedence bits and the five low-order bits as ToS bits.
The router software checks the source and destination addresses and port numbers of a packet to determine if the packet matches an RSVP reservation. If a match exists, as part of its input processing, RSVP checks the packet for conformance to the flowspec of the reservation. During this process, RSVP determines if the packet conforms to or exceeds the flowspec, and it sets the IP header IP Precedence and ToS bits of the packet accordingly.
To display the configured IP Precedence bit values and ToS bit values for an interface, use the show ip rsvp command.
Monitoring RSVP
To allow a user on a remote management station to monitor RSVP-related information, use the following command in global configuration mode:
After you configure the RSVP reservations that reflect your network resource policy, to verify the resulting RSVP operations, use the following commands in EXEC mode, as needed:
RSVP Configuration for a Multicast Session Example
Question for reviewers-----Is this example still applicable?
This section describes configuration of RSVP on three routers for a multicast session.
For information on how to configure RSVP, see the section "Resource Reservation Protocol Configuration Task List" in this chapter.
The three routers form the router network between an RSVP sender application running on an upstream (end system) host and an RSVP receiver application running on a downstream (end system) host—neither host is shown in this example.
The router network includes three routers: Router A, Router B, and Router C. The example presumes that the upstream High-Speed Serial Interface (HSSI) interface 0 of Router A links to the upstream host. Router A and Router B are connected by the downstream Ethernet interface1 of Router A, which links to the upstream interface Ethernet 1 of Router B. Router B and Router C are connected by the downstream HSSI interface 0 of Router B, which links to the upstream HSSI interface 0 of Router C. The example presumes that the downstream Ethernet interface 2 of Router C links to the downstream host.
Typically, an RSVP-capable application running on an end system host on one side of a router network sends either unicast or multicast RSVP PATH (Set Up) messages to the destination end system or host on the other side of the router network with which it wishes to communicate. The initiating application is referred to as the sender; the target or destination application is called the receiver. In this example, the sender runs on the host upstream from Router A and the receiver runs on the host downstream from Router C. The router network delivers the RSVP PATH messages from the sender to the receiver. The receiver replies with RSVP RESV messages in an attempt to reserve across the network the requested resources that are required between itself and the sender. The RSVP RESV messages specify the parameters for the requisite QoS that the router network connecting the systems should attempt to offer.
This example does not show the host that would run the sender application and the host that would run the receiver application. Normally, the first router downstream from the sender in the router network—in this case, Router A—would receive the RSVP PATH message from the sender. Normally, the last router in the router network—that is, the next hop upstream from the host running the receiver application, in this case, Router C—would receive an RSVP RESV message from the receiver.
Because this example does not explicitly include the hosts on which the sender and receiver applications run, the routers have been configured to act as if they were receiving PATH messages from a sender and RESV messages from a receiver. The commands used for this purpose, allowing RSVP to be more fully illustrated in the example, are the ip rsvp sender command and the ip rsvp reservation command. On Router A, the following command has been issued:
ip rsvp sender 225.1.1.1 12.1.2.1 UDP 7001 7000 12.1.2.1 Hs0 20 1This command causes the router to act as if it were receiving PATH messages destined to multicast address 225.1.1.1 from a source 12.1.2.1. The previous hop of the PATH message is 12.1.2.1, and the message was received on HSSI interface 0.
On Router C, the following command has been issued:
ip rsvp reservation 225.1.1.1 12.1.2.1 UDP 7001 7000 9.1.2.1 Et2 FF LOAD 8 1This command causes the router to act as if it were receiving RESV messages for the session with multicast destination 225.1.1.1. The messages request a Fixed Filter reservation to source 12.1.2.1, and act as if they had arrived from a receiver on Ethernet interface 2 with address 9.1.2.1.
In the example, the RSVP PATH messages flow in one direction: downstream from the sender, which in this example is Router A. (If the host were to initiate the RSVP PATH message, the message would flow from the host to Router A.) Router A sends the message downstream to Router B, and Router B sends it downstream to Router C. (If the downstream host were the actual receiver, Router C would send the RSVP PATH message downstream to the receiver host.) Each router in the router network must process the RSVP PATH message and route it to the next downstream hop.
The RSVP RESV messages flow in one direction: upstream from the receiver (in this example, Router C), upstream from Router C to Router B, and upstream from Router B to Router A. If the downstream host were the receiver, the message would originate with the host, which would send it to Router C. If the upstream host were the sender, the final destination of the RSVP RESV message would be the upstream host. At each hop, the router receiving the RSVP RESV message must determine whether it can honor the reservation request.
The ip rsvp bandwidth command both enables RSVP on an interface and specifies the amount of bandwidth on the interface that can be reserved (and the amount of bandwidth that can be allocated to a single flow). To ensure QoS for the RSVP reservation, WFQ is configured on the interfaces enabled for the reservation.
If the router network is capable of offering the specified (QoS) level of service, then an end-to-end reserved path is established. If not, the reservation attempt is rejected and a RESV ERROR message is sent to the receiver. The ability of each router in the network to honor the requested level of service is verified, link by link, as the RSVP RESV messages are sent across the router network to the sender. However, the data itself for which the bandwidth is reserved travels one way only: from the sender to receiver across an established PATH. Therefore, the QoS is effective in only one direction. This is the common case for one-to-many multicast data flows.
After the three routers in the example are configured, the show ip rsvp sender and show ip rsvp reservation commands will make visible the PATH and RESV state.
Router A Configuration
On Router A, RSVP is enabled on Ethernet interface 1 with 10 kbps to be reserved for the data transmission. A weighted fair queue is reserved on this interface to ensure RSVP QoS. (On Router A, RSVP is also enabled on HSSI interface 0 with 1 kbps reserved, but this bandwidth is used simply for passing messages.)
!version 12.0service configservice timestamps debug uptimeservice timestamps log uptimeno service password-encryptionservice udp-small-serversservice tcp-small-servers!hostname routerA!ip subnet-zerono ip domain-lookupip multicast-routingip dvmrp route-limit 20000!!interface Ethernet0ip address 2.0.0.193 255.0.0.0no ip directed-broadcastno ip route-cacheno ip mroute-cachemedia-type 10BaseT!interface Ethernet1ip address 11.1.1.2 255.0.0.0no ip directed-broadcastip pim dense-modeip rsvp bandwidth 10 10 fair-queue 64 256 1000media-type 10BaseT!interface Hssi0ip address 12.1.1.1 255.0.0.0no ip directed-broadcastip pim dense-modeip rsvp bandwidth 1 1!interface ATM0no ip addressno ip directed-broadcastshutdown!router ospf 100network 11.0.0.0 0.255.255.255 area 10network 12.0.0.0 0.255.255.255 area 10!ip classlessip rsvp sender 225.1.1.1 12.1.2.1 UDP 7001 7000 12.1.2.1 Hs0 20 1!line con 0exec-timeout 0 0length 0transport input noneline aux 0line vty 0 4login!endRouter B Configuration
On Router B, RSVP is enabled on HSSI interface 0 with 20 kbps to be reserved for the data transmission. A weighted fair queue is reserved on this interface to ensure RSVP QoS. (On Router B, RSVP is also enabled on Ethernet interface 1 with 1 kbps reserved, but this bandwidth is used simply for passing messages.)
!version 12.0service configservice timestamps debug uptimeservice timestamps log uptimeno service password-encryptionservice udp-small-serversservice tcp-small-servers!hostname routerB!ip subnet-zerono ip domain-lookupip multicast-routingip dvmrp route-limit 20000clock calendar-valid!interface Ethernet0ip address 2.0.0.194 255.0.0.0no ip directed-broadcastno ip route-cacheno ip mroute-cachemedia-type 10BaseT!interface Ethernet1ip address 11.1.1.1 255.0.0.0no ip directed-broadcastip pim dense-modeip rsvp bandwidth 1 1media-type 10BaseT!interface Hssi0ip address 10.1.1.2 255.0.0.0no ip directed-broadcastip pim dense-modeip rsvp bandwidth 20 20fair-queue 64 256 1000hssi internal-clock!interface ATM0no ip addressno ip directed-broadcastshutdown!router ospf 100network 10.0.0.0 0.255.255.255 area 10network 11.0.0.0 0.255.255.255 area 10!ip classless!line con 0exec-timeout 0 0length 0transport input noneline aux 0line vty 0 4login!endRouter C Configuration
On Router C, RSVP is enabled on Ethernet interface 2 with 20 kbps to be reserved for the data transmission. A weighted fair queue is reserved on this interface to ensure RSVP QoS. (On Router C, RSVP is also enabled on HSSI interface 0 with 1 kbps reserved, but this bandwidth is used simply for passing messages.)
!version 12.0service configservice timestamps debug uptimeservice timestamps log uptimeno service password-encryptionservice udp-small-serversservice tcp-small-servers!hostname routerC!ip subnet-zerono ip domain-lookupip multicast-routingip dvmrp route-limit 20000!interface Ethernet0ip address 2.0.0.195 255.0.0.0no ip directed-broadcastno ip route-cacheno ip mroute-cachemedia-type 10BaseT!interface Ethernet1no ip addressno ip directed-broadcastshutdownmedia-type 10BaseT!interface Ethernet2ip address 9.1.1.2 255.0.0.0no ip directed-broadcastip pim dense-modeip rsvp bandwidth 20 20 fair-queue 64 256 1000media-type 10BaseT!interface Ethernet3no ip addressno ip directed-broadcastshutdownmedia-type 10BaseT!interface Ethernet4no ip addressno ip directed-broadcastshutdownmedia-type 10BaseT!interface Ethernet5no ip addressno ip directed-broadcastshutdownmedia-type 10BaseT!interface Hssi0ip address 10.1.1.1 255.0.0.0no ip directed-broadcastip pim dense-modeip rsvp bandwidth 1 1hssi internal-clock!interface ATM0no ip addressno ip directed-broadcastshutdown!router ospf 100network 9.0.0.0 0.255.255.255 area 10network 10.0.0.0 0.255.255.255 area 10network 11.0.0.0 0.255.255.255 area 10!ip classlessip rsvp reservation 225.1.1.1 12.1.2.1 UDP 7001 7000 9.1.2.1 Et2 FF LOAD 8 1!line con 0exec-timeout 0 0length 0transport input noneline aux 0line vty 0 4login!endFeature Information for Configuring RSVP
Table 1 lists the features in this module and provides links to specific configuration information.
Use Cisco Feature Navigator to find information about platform support and software image support. Cisco Feature Navigator enables you to determine which Cisco IOS XE software images support a specific software release, feature set, or platform. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not required.
Note
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