Alcatel-Lucent 7450 Manual page 304

Interface Commands
refresh-reduction
Syntax [no] refresh-reduction
Context config>router>rsvp>interface
Description
This command enables the use of the RSVP overhead refresh reduction capabilities on this RSVP
interface.
When this option is enabled, a node will enable support for three capabilities. It will accept bundles
RSVP messages from its peer over this interface, it will attempt to perform reliable RSVP message
delivery to its peer, and will use summary refresh messages to refresh path and resv states. The
reliable message delivery must be explicitly enabled by the user after refresh reduction is enabled.
The other two capabilities are enabled immediately.
A bundle message is intended to reduce overall message handling load. A bundle message consists of
a bundle header followed by one or more bundle sub-messages. A sub-message can be any regular
RSVP message except another bundle message. A node will only process received bundled RSVP
messages but will not generate them.
When reliable message delivery is supported by both the node and its peer over the RSVP interface,
an RSVP message is sent with a message_id object. A message_id object can be added to any RSVP
message when sent individually or as a sub-message of a bundled message.
if the sender sets the ack_desired flag in the message_id object, the receiver acknowledges the receipt
of the RSVP message by piggy-backing a message_ack object to the next RSVP message it sends to
its peer. Alternatively, an ACK message can also be used to send the message_ack object. In both
cases, one or many message_ack objects could be included in the same message.
The
message_ack objects piggy-backed to hop-by-hop RSVP messages, such as path and resv.
The
which contain new state information.
A retransmission mechanism based on an exponential backoff timer is supported in order to handle
unacknowledged message_id objects. The RSVP message with the same message_id is retransmitted
every 2 * rapid-retransmit-time interval of time. The rapid-retransmit-time is referred to as the rapid
retransmission interval as it must be smaller than the regular refresh interval configured in the
config>router>rsvp>refresh-time context. There is also a maximum number of retransmissions of
an unacknowledged RSVP message rapid-retry-limit. The node will stop retransmission of
unacknowledged RSVP messages whenever the updated backoff interval exceeds the value of the
regular refresh interval or the number of retransmissions reaches the value of the rapid-retry-limit
parameter, whichever comes first. These two parameters are configurable globally on a system in the
config>router>rsvp context.
Refresh summary consists of sending a summary refresh message containing a message_id list
object. The fields of this object are populated each with the value of the message_identifier field in
the message_id object of a previously sent individual path or resv message. The summary refresh
message is sent every refresh regular interval as configured by the user using the refresh-time
command in the config>router>rsvp context. The receiver checks each message_id object against
the saved path and resv states. If a match is found, the state is updated as if a regular path or resv
refresh message was received from the peer. If a specific message_identifier field does not match,
then the node sends a message_id_nack object to the originator of the message.
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router
supportsthe sending of separate ACK messages only but is capable of processing received
router
sets the ack_desired flag only in non refresh RSVP messages and in refresh messages
7450 ESS MPLS Guide