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.

The RSVP Refresh Reduction and Reliable Messaging feature (see the figure below) 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)

• Reliable Messages
• Bundle Messages
• Summary Refresh Messages

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 typeand 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-poolarguments 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.

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.

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.