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HAPTER
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| Spanning Tree Algorithm
Overview
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lowest cost spanning tree, it enables all root ports and designated ports,
and disables all other ports. Network packets are therefore only forwarded
between root ports and designated ports, eliminating any possible network
loops.
Figure 90: STP Root Ports and Designated Ports
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 much 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 maintain
connectivity among each of the assigned VLAN groups. MSTP then builds a
Internal Spanning Tree (IST) for the Region containing all commonly
configured MSTP bridges.
x
Designated
Root
Designated
Port
Designated
Bridge
x
x
x
Root
Port
x
Содержание DG-FS4526E
Страница 4: ...ABOUT THIS GUIDE 4...
Страница 34: ...CONTENTS 34...
Страница 50: ...TABLES 50...
Страница 52: ...SECTION I Getting Started 52...
Страница 62: ...CHAPTER 1 Introduction System Defaults 62...
Страница 80: ...CHAPTER 2 Initial Switch Configuration Managing System Files 80...
Страница 82: ...SECTION II Web Configuration 82...
Страница 100: ...CHAPTER 3 Using the Web Interface Navigating the Web Browser Interface 100...
Страница 128: ...CHAPTER 4 Basic Management Tasks Resetting the System 128...
Страница 166: ...CHAPTER 5 Interface Configuration VLAN Trunking 166...
Страница 198: ...CHAPTER 6 VLAN Configuration Configuring VLAN Mirroring 198...
Страница 516: ...CHAPTER 17 IP Services Displaying the DNS Cache 516...
Страница 562: ...CHAPTER 19 Using the Command Line Interface CLI Command Groups 562...
Страница 652: ...CHAPTER 22 SNMP Commands 652...
Страница 660: ...CHAPTER 23 Remote Monitoring Commands 660...
Страница 714: ...CHAPTER 24 Authentication Commands Management IP Filter 714...
Страница 802: ...CHAPTER 27 Interface Commands 802...
Страница 824: ...CHAPTER 29 Port Mirroring Commands RSPAN Mirroring Commands 824...
Страница 846: ...CHAPTER 32 Address Table Commands 846...
Страница 874: ...CHAPTER 33 Spanning Tree Commands 874...
Страница 886: ...CHAPTER 34 ERPS Commands 886...
Страница 928: ...CHAPTER 35 VLAN Commands Configuring Voice VLANs 928...
Страница 942: ...CHAPTER 36 Class of Service Commands Priority Commands Layer 3 and 4 942...
Страница 998: ...CHAPTER 38 Multicast Filtering Commands Multicast VLAN Registration 998...
Страница 1022: ...CHAPTER 39 LLDP Commands 1022...
Страница 1064: ...CHAPTER 40 CFM Commands 1064...
Страница 1084: ...CHAPTER 42 Domain Name Service Commands 1084...
Страница 1090: ...CHAPTER 43 DHCP Commands DHCP Client 1090...
Страница 1122: ...CHAPTER 44 IP Interface Commands IPv6 Interface 1122...
Страница 1124: ...SECTION IV Appendices 1124...
Страница 1129: ...APPENDIX A Software Specifications Management Information Bases 1129 Trap RFC 1215 UDP MIB RFC 2013...
Страница 1130: ...APPENDIX A Software Specifications Management Information Bases 1130...
Страница 1152: ...COMMAND LIST 1152...
Страница 1161: ......
Страница 1162: ...DG FS4526E 042012 HW R01...