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6-2
C
HAPTER
6: S
PANNING
T
REE
P
ROTOCOL
What is STP?
STP is a bridge-based system for providing fault tolerance on networks.
It allows you to implement parallel paths for network traffic, and
ensure that:
■
Redundant paths are disabled when the main paths are operational
■
Redundant paths are enabled if the main paths fail
As an example, Figure 6-1 shows a network containing three LAN
segments separated by three bridges. With this configuration, each
segment can communicate with the others using two paths. This
configuration creates loops which cause the network to overload;
however, STP allows you to have this configuration because it detects
duplicate paths and immediately prevents, or
blocks
, one of them from
forwarding traffic.
Figure 6-2 shows the result of enabling STP on the bridges in the
configuration. The STP system has decided that traffic from LAN
segment 2 to LAN segment 1 can only flow through Bridges C and A.
If the link through Bridge C fails, as shown in Figure 6-3, the STP
system reconfigures the network so that traffic from segment 2 flows
through Bridge B.
Figure 6-1
A network configuration that creates loops
F24user.bk Page 2 Wednesday, July 15, 1998 4:27 PM
Summary of Contents for 8271 Nways Ethernet LAN Switch
Page 10: ...viii F24user bk Page viii Wednesday July 15 1998 4 27 PM...
Page 14: ...4 SAFETY NOTICES F24user bk Page 4 Wednesday July 15 1998 4 27 PM...
Page 15: ...Safety Notices 5 F24user bk Page 5 Wednesday July 15 1998 4 27 PM...
Page 16: ...6 SAFETY NOTICES F24user bk Page 6 Wednesday July 15 1998 4 27 PM...
Page 20: ...10 ABOUT THIS GUIDE F24user bk Page 10 Wednesday July 15 1998 4 27 PM...
Page 22: ...F24user bk Page 2 Wednesday July 15 1998 4 27 PM...
Page 38: ...1 16 CHAPTER 1 INTRODUCING THE SWITCH F24user bk Page 16 Wednesday July 15 1998 4 27 PM...
Page 58: ...3 10 CHAPTER 3 SETTING UP FOR MANAGEMENT F24user bk Page 10 Wednesday July 15 1998 4 27 PM...
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Page 122: ...F24user bk Page 2 Wednesday July 15 1998 4 27 PM...
Page 139: ...IV PROBLEM SOLVING Chapter 8 Problem Solving F24user bk Page 9 Wednesday July 15 1998 4 27 PM...
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Page 150: ...8 10 CHAPTER 8 PROBLEM SOLVING F24user bk Page 10 Wednesday July 15 1998 4 27 PM...
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Page 157: ...Important Safety Information A 5 F24user bk Page 5 Wednesday July 15 1998 4 27 PM...
Page 173: ...Important Safety Information A 21 F24user bk Page 21 Wednesday July 15 1998 4 27 PM...
Page 174: ...A 22 APPENDIX A SAFETY INFORMATION F24user bk Page 22 Wednesday July 15 1998 4 27 PM...
Page 184: ...D 4 APPENDIX D PIN OUTS F24user bk Page 4 Wednesday July 15 1998 4 27 PM...
Page 188: ...F 2 APPENDIX F TECHNICAL SUPPORT AND SERVICE F24user bk Page 2 Wednesday July 15 1998 4 27 PM...
Page 210: ...6 INDEX F24user bk Page 6 Wednesday July 15 1998 4 27 PM...