Alcatel-Lucent 1643 AMS - Rapid spanning tree protocol (rSTP)

Ports that are neither root ports nor designated ports are blocked. In the example port
2c is a blocked port.
Thus the loop free spanning tree is constructed.
Rapid spanning tree protocol (rSTP)
The rapid spanning tree protocol reduces the time that the standard spanning tree
protocol needs to reconfigure after network failures. Instead of several tens of seconds,
rSTP can reconfigure in less than a second. The actual reconfiguration time depends on
several parameters, the two most prominent are the network size and complexity.
IEEE802.1w describes the standard implementation for rSTP.
Specific attributes for TransLAN
®
STP enhancements:
• Failure Detection - Use SDH-layer failure detection to trigger STP reconfiguration.
• Convergence Time - Key aspects of the message-based IEEE 802.1w/D10 (rSTP)
protocol instead of timer-based 802.1D (STP) protocol.
• Support larger network diameter by adjusting the “Maximum Age Timer” parameter
and enhanced STP configuration controls and reports.
• Automatic mode detection - The rSTP is supported as an enhancement to STP, it
cannot be enabled explicitly. It rather will operate by default and will fall back to
STP as soon as it finds peer nodes that do not support rSTP. The STP mode that
the bridge elected can be retrieved per port.
LAN 1
1a
Root
3a
3b
3c
1c
1b
2c
2b
2a
Switch 1
Switch 2
Switch 3
LAN 3
LAN 4
LAN 5
LAN 6
LAN 2
x
r
r
d
d
d
d
d
d
Traffic provisioning Spanning tree protocol (STP)
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Alcatel-Lucent - Proprietary
See notice on first page
365-312-807R7.2
Issue 4, May 2007