RSVP Refresh Reduction and Reliable Messaging

First Published: November 25, 2002
Last Updated: February 27, 2009

The RSVP Refresh Reduction and Reliable Messaging feature includes refresh reduction, which improves the scalability, latency, and reliability of Resource Reservation Protocol (RSVP) signaling to enhance network performance and message delivery.

History for the RSVP Refresh Reduction and Reliable Messaging Feature

Release
Modification

12.2(13)T

This feature was introduced.

12.0(24)S

This feature was integrated into Cisco IOS Release 12.0(24)S.

12.2(14)S

This feature was integrated into Cisco IOS Release 12.2(14)S.

12.0(26)S

Two commands, ip rsvp signalling refresh misses and ip rsvp signalling refresh interval, were added into Cisco IOS Release 12.0(26)S.

12.0(29)S

The burst and max-size argument defaults for the ip rsvp signalling rate-limit command were increased to 8 messages and 2000 bytes, respectively.

12.2(28)SB

This feature was integrated into Cisco IOS Release 12.2(28)SB.

12.2(18)SXF5

This feature was integrated into Cisco IOS Release 12.2(18)SXF5.

12.2(33)SRB

This feature was integrated into Cisco IOS Release 12.2(33)SRB.


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Contents

•Prerequisites for RSVP Refresh Reduction and Reliable Messaging

•Restrictions for RSVP Refresh Reduction and Reliable Messaging

•Information About RSVP Refresh Reduction and Reliable Messaging

•How to Configure RSVP Refresh Reduction and Reliable Messaging

•Configuration Examples for RSVP Refresh Reduction and Reliable Messaging

•Additional References

•Command Reference

Prerequisites for RSVP Refresh Reduction and Reliable Messaging

RSVP must be configured on two or more routers within the network before you can use the RSVP Refresh Reduction and Reliable Messaging feature.

Restrictions for RSVP Refresh Reduction and Reliable Messaging

Multicast flows are not supported for the reliable messages and summary refresh features.

Information About RSVP Refresh Reduction and Reliable Messaging

To configure the RSVP Refresh Reduction and Reliable Messaging feature, you should understand the following concepts:

•Feature Design of RSVP Refresh Reduction and Reliable Messaging

•Types of Messages in RSVP Refresh Reduction and Reliable Messaging

•Benefits of RSVP Refresh Reduction and Reliable Messaging

Feature Design of RSVP Refresh Reduction and Reliable Messaging

RSVP is a network-control, soft-state protocol that enables Internet applications to obtain special qualities of service (QoS) for their data flows. As a soft-state protocol, RSVP requires that state be periodically refreshed. If refresh messages are not transmitted during a specified interval, RSVP state automatically times out and is deleted.

In a network that uses RSVP signaling, reliability and latency problems occur when an RSVP message is lost in transmission. A lost RSVP setup message can cause a delayed or failed reservation; a lost RSVP refresh message can cause a delay in the modification of a reservation or in a reservation timeout. Intolerant applications can fail as a result.

Reliability problems can also occur when there is excessive RSVP refresh message traffic caused by a large number of reservations in the network. Using summary refresh messages can improve reliability by significantly reducing the amount of RSVP refresh traffic.

Note RSVP packets consist of headers that identify the types of messages, and object fields that contain attributes and properties describing how to interpret and act on the content.

Types of Messages in RSVP Refresh Reduction and Reliable Messaging

The RSVP Refresh Reduction and Reliable Messaging feature (Figure 1) includes refresh reduction, which improves the scalability, latency, and reliability of RSVP signaling by introducing the following extensions:

•Reliable messages (MESSAGE_ID, MESSAGE_ID_ACK objects, and ACK messages)

•Bundle messages (reception and processing only)

•Summary refresh messages (MESSAGE_ID_LIST and MESSAGE_ID_NACK objects)

Figure 1 RSVP Refresh Reduction and Reliable Messaging

Reliable Messages

The reliable messages extension supports dependable message delivery among neighboring routers by implementing an acknowledgment mechanism that consists of a MESSAGE_ID object and a MESSAGE_ID_ACK object. The acknowledgments can be transmitted in an ACK message or piggybacked in other RSVP messages.

Each RSVP message contains one MESSAGE_ID object. If the ACK_Desired flag field is set within the MESSAGE_ID object, the receiver transmits a MESSAGE_ID_ACK object to the sender to confirm delivery.

Bundle Messages

A bundle message consists of several standard RSVP messages that are grouped into a single RSVP message.

A bundle message must contain at least one submessage. A submessage can be any RSVP message type other than another bundle message. Submessage types include Path, PathErr, Resv, ResvTear, ResvErr, ResvConf, and ACK.

Bundle messages are addressed directly to the RSVP neighbor. The bundle header immediately follows the IP header, and there is no intermediate transport header.

When a router receives a bundle message that is not addressed to one of its local IP addresses, it forwards the message.

Note Bundle messages can be received, but not sent.

Summary Refresh Messages

A summary refresh message supports the refreshing of RSVP state without the transmission of conventional Path and Resv messages. Therefore, the amount of information that must be transmitted and processed to maintain RSVP state synchronization is greatly reduced.

A summary refresh message carries a set of MESSAGE_ID objects that identify the Path and Resv states that should be refreshed. When an RSVP node receives a summary refresh message, the node matches each received MESSAGE_ID object with the locally installed Path or Resv state. If the MESSAGE_ID objects match the local state, the state is updated as if a standard RSVP refresh message were received. However, if a MESSAGE_ID object does not match the receiver's local state, the receiver notifies the sender of the summary refresh message by transmitting a MESSAGE_ID_NACK object.

When a summary refresh message is used to refresh the state of an RSVP session, the transmission of conventional refresh messages is suppressed. The summary refresh extension cannot be used for a Path or Resv message that contains changes to a previously advertised state. Also, only a state that was previously advertised in Path or Resv messages containing MESSAGE_ID objects can be refreshed by using a summary refresh message.

Benefits of RSVP Refresh Reduction and Reliable Messaging

Enhanced Network Performance

Refresh reduction reduces the volume of steady-state network traffic generated, the amount of CPU resources used, and the response time, thereby enhancing network performance.

Improved Message Delivery

The MESSAGE_ID and the MESSAGE_ID_ACK objects ensure the reliable delivery of messages and support rapid state refresh when a network problem occurs. For example, MESSAGE_ID_ACK objects are used to detect link transmission losses.

How to Configure RSVP Refresh Reduction and Reliable Messaging

This section contains the following procedures:

•Enabling RSVP on an Interface (required)

•Enabling RSVP Refresh Reduction (required)

•Verifying RSVP Refresh Reduction and Reliable Messaging (optional)

Enabling RSVP on an Interface

Perform the following task to enable RSVP on an interface.

SUMMARY STEPS

1. enable

2. configure terminal

3. interface type number

4. ip rsvp bandwidth [interface-kbps [sub-pool]]

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 number

Example:

Router(config)# interface Ethernet1

Enters interface configuration mode.

•The type and number arguments identify the interface to be configured.

Step 4 

ip rsvp bandwidth [interface-kbps [sub-pool]]

Example:

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

Enables RSVP on an interface.

•The optional interface-kbps and sub-pool arguments specify the amount of bandwidth that can be allocated by RSVP flows or to a single flow, respectively. Values are from 1 to 10000000, and from 0 to 10000000, respectively.

Step 5 

end

Example:

Router(config-if)# end

Returns to privileged EXEC mode.


Enabling RSVP Refresh Reduction

Perform the following task to enable RSVP refresh reduction.

SUMMARY STEPS

1. enable

2. configure terminal

3. ip rsvp signalling refresh reduction

4. 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 

ip rsvp signalling refresh reduction

Example:

Router(config)# ip rsvp signalling refresh reduction

Enables refresh reduction.

Step 4 

end

Example:

Router(config)# end

Returns to privileged EXEC mode.


Verifying RSVP Refresh Reduction and Reliable Messaging

Perform the following task to verify that the RSVP Refresh Reduction and Reliable Messaging feature is functioning.

SUMMARY STEPS

1. enable

2. clear ip rsvp counters [confirm]

3. show ip rsvp

4. show ip rsvp counters [interface interface-unit | summary | neighbor]

5. show ip rsvp interface [interface-type interface-number] [detail]

6. show ip rsvp neighbor [detail]

DETAILED STEPS

 
Command or Action
Purpose

Step 1 

enable

Example:

Router> enable

Enables privileged EXEC mode.

•Enter your password if prompted.

Step 2 

clear ip rsvp counters [confirm]

Example:

Router# clear ip rsvp counters

(Optional) Clears (sets to zero) all IP RSVP counters that are being maintained by the router.

Step 3 

show ip rsvp

Example:

Router# show ip rsvp

(Optional) Displays RSVP rate-limiting, refresh-reduction, and neighbor information.

Step 4 

show ip rsvp counters [interface interface-unit | summary | neighbor]

Example:

Router# show ip rsvp counters summary

(Optional) Displays the number of RSVP messages that were sent and received on each interface.

•The optional summary keyword displays the cumulative number of RSVP messages sent and received by the router over all interfaces.

Step 5 

show ip rsvp interface [interface-type interface-number] [detail]

Example:

Router# show ip rsvp interface detail

(Optional) Displays information about interfaces on which RSVP is enabled including the current allocation budget and maximum available bandwidth.

•The optional detail keyword displays the bandwidth and signaling parameters.

Step 6 

show ip rsvp neighbor [detail]

Example:

Router# show ip rsvp neighbor detail

(Optional) Displays RSVP-neighbor information including IP addresses.

•The optional detail keyword displays the current RSVP neighbors and identifies if the neighbor is using IP, User Datagram Protocol (UDP), or RSVP encapsulation for a specified interface or all interfaces.

Configuration Examples for RSVP Refresh Reduction and Reliable Messaging

This section provides the following configuration example:

•Example: RSVP Refresh Reduction and Reliable Messaging

Example: RSVP Refresh Reduction and Reliable Messaging

In the following example, RSVP refresh reduction is enabled: 

Router# configure terminal


Enter configuration commands, one per line. End with CNTL/Z.

Router(config)# interface Ethernet1

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

Router(config-if)# exit

Router(config)# ip rsvp signalling refresh reduction

Router(config)# end

The following example verifies that RSVP refresh reduction is enabled: 

Router# show running-config


Building configuration...

Current configuration : 1503 bytes


!

version 12.2

no service single-slot-reload-enable

service timestamps debug uptime

service timestamps log uptime

no service password-encryption

service internal

!

hostname Router

!

no logging buffered

logging rate-limit console 10 except errors

!

ip subnet-zero

ip cef

!

ip multicast-routing

no ip dhcp-client network-discovery

lcp max-session-starts 0

mpls traffic-eng tunnels

!

!

interface Loopback0

 ip address 192.168.1.1 255.255.255.0

 ip rsvp bandwidth 1705033 1705033

!

interface Tunnel777

 no ip address

 shutdown

!

interface Ethernet0

 ip address 192.168.0.195 255.0.0.0

 no ip mroute-cache

 media-type 10BaseT

!

interface Ethernet1

 ip address 192.168.5.2 255.255.255.0

 no ip redirects

 no ip proxy-arp

 ip pim dense-mode

 no ip mroute-cache

 media-type 10BaseT

 ip rsvp bandwidth 7500 7500

!

interface Ethernet2

 ip address 192.168.1.2 255.255.255.0

 no ip redirects

 no ip proxy-arp

 ip pim dense-mode

 no ip mroute-cache

 media-type 10BaseT

 mpls traffic-eng tunnels

 ip rsvp bandwidth 7500 7500

!

interface Ethernet3

 ip address 192.168.2.2 255.255.255.0

 ip pim dense-mode

 media-type 10BaseT

 mpls traffic-eng tunnels

!

!

router eigrp 17

 network 192.168.0.0

 network 192.168.5.0

 network 192.168.12.0

 network 192.168.30.0

 auto-summary

 no eigrp log-neighbor-changes

!

ip classless

no ip http server

ip rsvp signalling refresh reduction

!

!

!

!

line con 0

 exec-timeout 0 0

line aux 0

line vty 0 4

 login

 transport input pad v120 telnet rlogin udptn

!

end

Additional References

The following sections provide references related to the RSVP Refresh Reduction and Reliable Messaging feature.

Related Documents

Related Topic
Document Title

Cisco IOS commands

Cisco IOS Master Commands List, All Releases

RSVP commands: complete command syntax, command mode, defaults, usage guidelines, and examples

 Cisco IOS Quality of Service Solutions Command Reference

QoS features including signaling, classification, and congestion management

"Quality of Service Overview" module


Standards

Standard
Title

None

—


MIBs

MIB
MIBs Link

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

To locate and download MIBs for selected platforms, Cisco IOS 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

RFC 2209

RSVP—Version 1 Message Processing Rules

RFC 2210

The Use of RSVP with IETF Integrated Services

RFC 2211/2212

Specification of the Controlled-Load Network Element Service

RFC 2702

Requirements for Traffic Engineering over MPLS

RFC 2749

Common Open Policy Service (COPS) Usage for RSVP

RFC 2750

RSVP Extensions for Policy Control

RFC 2814

SBM Subnet Bandwidth Manager: A Protocol for RSVP-based Admission Control over IEEE 802-style Networks

RFC 2961

RSVP Refresh Overhead Reduction Extensions

RFC 2996

Format of the RSVP DCLASS Object


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


Command Reference

The following commands are introduced or modified in the feature or features documented in this module. For information about these commands, see the Cisco IOS Quality of Service Solutions Command Reference at http://www.cisco.com/en/US/docs/ios/qos/command/reference/qos_book.html. For information about all Cisco IOS commands, use the Command Lookup Tool at http://tools.cisco.com/Support/CLILookup or a Cisco IOS master commands list.

•ip rsvp signalling rate-limit

•show ip rsvp signalling rate-limit

Cisco and the Cisco Logo are trademarks of Cisco Systems, Inc. and/or its affiliates in the U.S. and other countries. A listing of Cisco's trademarks can be found at www.cisco.com/go/trademarks. Third party trademarks mentioned are the property of their respective owners. The use of the word partner does not imply a partnership relationship between Cisco and any other company. (1005R)

Any Internet Protocol (IP) addresses used in this document are not intended to be actual addresses. Any examples, command display output, and figures included in the document are shown for illustrative purposes only. Any use of actual IP addresses in illustrative content is unintentional and coincidental.

© 2002-2009 Cisco Systems, Inc. All rights reserved.