Transcript Powerpoint

Hierarchical Refresh
• Simple idea – for scaling of refreshes, use the
same mechanism, but apply it to the Srefresh
messages themselves
• Srefresh messages so refreshed are treated
as if they had been newly received
• We’ll use the notation S2refresh for the
second level refresh
Traffic Eng.
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Sender Side
• Include a message ID in Srefresh messages with
the Ack request bit set
• Time_Values object permitted in Srefresh
• When acked the message ID can be placed in a
second level summary refresh (S2refresh)
• S2refresh need not carry message ID or be acked
• Note that it is not germane to this scheme that all
Srefresh messages use the hierarchy
Traffic Eng.
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Receiver Side Refresh
• Ack and save Srefresh messages
set timeout to according to time-values object
• Reset timers on retransmission of the Srefresh
message or if Message ID listed in a S2refresh
• Upon receipt of an S2refresh
Nack any message Ids for which no message is found
Reprocess each refreshed Srefresh as if it had just been
received
Traffic Eng.
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Dropping a Message ID
When a message with ID ‘m’ has timed-out
• Locate Srefresh message containing the
Message-ID ‘m’
• Note the Srefresh’s own Message-ID ‘s’
• Drop the Message ID ‘m’ from Srefresh ‘s’
• Locate the S2refresh which contains ‘s’
• Drop ‘s’ from this message
• Pick a new Message ID for the Srefresh ‘s*’
Traffic Eng.
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Dropping a Message ID(2)
• Pick a new Message ID for the Srefresh ‘s*’
• Set the ack-request bit
• When acked, s* can be added to a
S2refresh message
Traffic Eng.
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