S
PANNING
T
REE
A
LGORITHM
10-2
Once a stable network topology has been established, all bridges listen for
Hello BPDUs (Bridge Protocol Data Units) transmitted from the Root
Bridge. If a bridge does not get a Hello BPDU after a predefined interval
(Maximum Age), the bridge assumes that the link to the Root Bridge is
down. This bridge will then initiate negotiations with other bridges to
reconfigure the network to reestablish a valid network topology.
RSTP
– RSTP is designed as a general replacement for the slower, legacy
STP. RSTP is also incorporated into MSTP. RSTP achieves must faster
reconfiguration (i.e., around 1 to 3 seconds, compared to 30 seconds or
more for STP) by reducing the number of state changes before active ports
start learning, predefining an alternate route that can be used when a node
or port fails, and retaining the forwarding database for ports insensitive to
changes in the tree structure when reconfiguration occurs.
MSTP
– When using STP or RSTP, it may be difficult to maintain a stable
path between all VLAN members. Frequent changes in the tree structure
can easily isolate some of the group members. MSTP (which is based on
RSTP for fast convergence) is designed to support independent spanning
trees based on VLAN groups. Using multiple spanning trees can provide
multiple forwarding paths and enable load balancing. One or more VLANs
can be grouped into a Multiple Spanning Tree Instance (MSTI). MSTP
builds a separate Multiple Spanning Tree (MST) for each instance to
x
Designated
Root
Designated
Port
Designated
Bridge
x
x
x
Root
Port
x
Summary of Contents for WPCI-G - annexe 1
Page 2: ......
Page 26: ...TABLE OF CONTENTS xxvi ...
Page 36: ...GETTING STARTED ...
Page 72: ...MANAGING SYSTEM FILES 2 24 ...
Page 74: ...SWITCH MANAGEMENT ...
Page 90: ...CONFIGURING THE SWITCH 3 16 ...
Page 245: ...SHOWING PORT STATISTICS 8 33 Figure 8 12 Port Statistics ...
Page 252: ...ADDRESS TABLE SETTINGS 9 6 ...
Page 318: ...CLASS OF SERVICE 12 16 ...
Page 330: ...QUALITY OF SERVICE 13 12 ...
Page 348: ...DOMAIN NAME SERVICE 15 8 ...
Page 404: ...IP ROUTING 17 44 ...
Page 406: ...COMMAND LINE INTERFACE ...
Page 608: ...MIRROR PORT COMMANDS 26 4 ...
Page 644: ...SPANNING TREE COMMANDS 29 28 ...
Page 668: ...VLAN COMMANDS 30 24 ...
Page 686: ...CLASS OF SERVICE COMMANDS 31 18 ...
Page 700: ...QUALITY OF SERVICE COMMANDS 32 14 ...
Page 792: ...IP INTERFACE COMMANDS 36 50 ...
Page 818: ...APPENDICES ...
Page 824: ...SOFTWARE SPECIFICATIONS A 6 ...
Page 828: ...TROUBLESHOOTING B 4 ...
Page 844: ...INDEX Index 6 ...
Page 845: ......