Medium Access Control (MAC) and Physical Layer (PHY) - CISE

4-June-07 P1901_PRO_016_r0
Range: [6, 40] seconds
Priority: The greater the number, the less priority.
Table 57 STP priority
IEEE 802.1w (Rapid STP)
MV Master 0x9010
MV Repeater 0x9020
LV Master 0x9030
LV Repeater 0x9040
LV Slave 0x9050
Rapid Spanning Tree Protocol (RSTP; IEEE 802.1w) is an amendment to 802.1D. This version offers a significant
reduction in the time taken to reconfigure the active topology of the Bridged LAN in the face of changes to the
physical topology or its configuration parameters. The strategy to reach this performance is based on a handshake
mechanism between bridges that enables a fast transition to forwarding, thus bypassing the listening and learning
states and timers.
The two versions of the algorithm and protocol are capable of interoperating within the same Bridged LAN; hence,
it is not necessary for implementations to support both versions of the Spanning Tree algorithm and protocol.
In view of the improved performance offered, it is recommended that the Rapid Spanning Tree algorithm and
Protocol be supported in preference to the original version.
For specific information on message types and their format, the migration protocol and the RSTP algorithm, refer to
IEEE Std 802.1D, 1998 Edition; Clause 17 (Rapid Spanning Tree Algorithm and Protocol), also found as 802.1w.
Default timers and field values
migration delay (mdelay): indicates that the protocol migration is ongoing. It is used to avoid re-entry. If any BPDU
of the other type is received while mdelay is running, it is ignored in terms of protocol migration. mdelay is set to 3
seconds.
Submission page 278 UPA-OPERA