C
HAPTER
8
| Spanning Tree Algorithm
Overview
– 194 –
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 ES3510MA
Страница 1: ...Management Guide www edge core com 8 Port Layer 2 Fast Ethernet Switch...
Страница 4: ...ABOUT THIS GUIDE 4...
Страница 30: ...CONTENTS 30...
Страница 40: ...FIGURES 40...
Страница 46: ...TABLES 46...
Страница 48: ...SECTION I Getting Started 48...
Страница 72: ...SECTION II Web Configuration 72...
Страница 88: ...CHAPTER 3 Using the Web Interface Navigating the Web Browser Interface 88...
Страница 115: ...CHAPTER 4 Basic Management Tasks Resetting the System 115 Figure 23 Restarting the Switch Regularly...
Страница 116: ...CHAPTER 4 Basic Management Tasks Resetting the System 116...
Страница 154: ...CHAPTER 5 Interface Configuration VLAN Trunking 154...
Страница 216: ...CHAPTER 8 Spanning Tree Algorithm Configuring Interface Settings for MSTP 216...
Страница 350: ...CHAPTER 14 Security Measures DHCP Snooping 350...
Страница 440: ...CHAPTER 17 IP Services Displaying the DNS Cache 440...
Страница 484: ...CHAPTER 19 Using the Command Line Interface CLI Command Groups 484...
Страница 554: ...CHAPTER 21 System Management Commands Switch Clustering 554...
Страница 574: ...CHAPTER 22 SNMP Commands 574...
Страница 582: ...CHAPTER 23 Remote Monitoring Commands 582...
Страница 636: ...CHAPTER 24 Authentication Commands Management IP Filter 636...
Страница 736: ...CHAPTER 29 Port Mirroring Commands RSPAN Mirroring Commands 736...
Страница 816: ...CHAPTER 34 VLAN Commands Configuring Voice VLANs 816...
Страница 830: ...CHAPTER 35 Class of Service Commands Priority Commands Layer 3 and 4 830...
Страница 848: ...CHAPTER 36 Quality of Service Commands 848...
Страница 900: ...CHAPTER 38 LLDP Commands 900...
Страница 910: ...CHAPTER 39 Domain Name Service Commands 910...
Страница 916: ...CHAPTER 40 DHCP Commands DHCP Client 916...
Страница 948: ...CHAPTER 41 IP Interface Commands IPv6 Interface 948...
Страница 950: ...SECTION IV Appendices 950...
Страница 982: ...INDEX 982...
Страница 983: ......
Страница 984: ...ES3510MA E032010 ST R01 149100000046A...