S
PANNING
T
REE
A
LGORITHM
11-2
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 7824M/FSW - annexe 1
Page 2: ......
Page 24: ...TABLE OF CONTENTS xxiv ...
Page 28: ...TABLES xxviii ...
Page 32: ...FIGURES xxxii Figure 16 3 DNS Cache 16 7 ...
Page 34: ...GETTING STARTED ...
Page 46: ...SYSTEM DEFAULTS 1 12 ...
Page 62: ...SWITCH MANAGEMENT ...
Page 74: ...CONFIGURING THE SWITCH 3 12 ...
Page 112: ...BASIC MANAGEMENT TASKS 4 38 ...
Page 168: ...USER AUTHENTICATION 6 30 ...
Page 223: ...SHOWING PORT STATISTICS 9 33 Figure 9 12 Port Statistics ...
Page 230: ...ADDRESS TABLE SETTINGS 10 6 ...
Page 304: ...CLASS OF SERVICE 13 16 ...
Page 316: ...QUALITY OF SERVICE 14 12 ...
Page 338: ...MULTICAST FILTERING 15 22 ...
Page 346: ...DOMAIN NAME SERVICE 16 8 ...
Page 348: ...COMMAND LINE INTERFACE IP Interface Commands 35 1 ...
Page 362: ...OVERVIEW OF COMMAND LINE INTERFACE 17 14 ...
Page 494: ...USER AUTHENTICATION COMMANDS 21 48 ...
Page 514: ...CLIENT SECURITY COMMANDS 22 20 ...
Page 540: ...ACCESS CONTROL LIST COMMANDS 23 26 ...
Page 558: ...INTERFACE COMMANDS 24 18 ...
Page 576: ...MIRROR PORT COMMANDS 26 4 ...
Page 582: ...RATE LIMIT COMMANDS 27 6 ...
Page 616: ...SPANNING TREE COMMANDS 29 28 ...
Page 644: ...VLAN COMMANDS 30 28 ...
Page 664: ...CLASS OF SERVICE COMMANDS 31 20 ...
Page 678: ...QUALITY OF SERVICE COMMANDS 32 14 ...
Page 720: ...APPENDICES ...
Page 726: ...SOFTWARE SPECIFICATIONS A 6 ...
Page 730: ...TROUBLESHOOTING B 4 ...
Page 746: ...INDEX Index 6 ...
Page 747: ......