Chapter 22: Spanning Tree and Rapid Spanning Tree Protocols
238
Section V: Spanning Tree Protocols
Bridge Priority and the Root Bridge
The first task that bridges perform when a spanning tree protocol is
activated on a network is the selection of a
root bridge
. A root bridge
distributes network topology information to the other network bridges and
is used by the other bridges to determine if there are redundant paths in
the network.
A root bridge is selected by the
bridge priority
number, also referred to as
the bridge identifier, and sometimes the bridge’s MAC address. The bridge
with the lowest bridge priority number in the network is selected as the
root bridge. If two or more bridges have the same bridge priority number,
of those bridges the one with the lowest MAC address is designated as
the root bridge.
You can change the bridge priority number in the AT-S63 Management
Software. You can designate which switch on your network you want as
the root bridge by giving it the lowest bridge priority number. You might
also consider which bridge should function as the backup root bridge in
the event you need to take the primary root bridge offline, and assign that
bridge the second lowest bridge identifier number.
The bridge priority has a range 0 to 61440 in increments of 4096. To make
this easier for you, the AT-S63 Management Software divides the range
into increments. You specify the increment that represents the desired
bridge priority value. The range is divided into sixteen increments, as
shown in Table 70.
Table 70. Bridge Priority Value Increments
Increment
Bridge
Priority
Increment
Bridge
Priority
0
0
8
32768
1
4096
9
36864
2
8192
10
40960
3
12288
11
45056
4
16384
12
49152
5
20480
13
53248
6
24576
14
57344
7
28672
15
61440
Содержание AT-S63
Страница 14: ...Figures 14 ...
Страница 18: ...Tables 18 ...
Страница 28: ...28 Section I Basic Operations ...
Страница 58: ...Chapter 1 Overview 58 ...
Страница 76: ...Chapter 2 AT 9400Ts Stacks 76 Section I Basic Operations ...
Страница 96: ...Chapter 5 MAC Address Table 96 Section I Basic Operations ...
Страница 114: ...Chapter 8 Port Mirror 114 Section I Basic Operations ...
Страница 116: ...116 Section II Advanced Operations ...
Страница 146: ...Chapter 12 Access Control Lists 146 Section II Advanced Operations ...
Страница 176: ...Chapter 14 Quality of Service 176 Section II Advanced Operations ...
Страница 196: ...196 Section III Snooping Protocols ...
Страница 204: ...Chapter 18 Multicast Listener Discovery Snooping 204 Section III Snooping Protocols ...
Страница 216: ...Chapter 20 Ethernet Protection Switching Ring Snooping 216 Section III Snooping Protocols ...
Страница 218: ...218 Section IV SNMPv3 ...
Страница 234: ...234 Section V Spanning Tree Protocols ...
Страница 268: ...268 Section VI Virtual LANs ...
Страница 306: ...Chapter 27 Protected Ports VLANs 306 Section VI Virtual LANs ...
Страница 320: ...320 Section VII Internet Protocol Routing ...
Страница 360: ...Chapter 30 BOOTP Relay Agent 360 Section VII Routing ...
Страница 370: ...Chapter 31 Virtual Router Redundancy Protocol 370 Section VII Routing ...
Страница 372: ...372 Section VIII Port Security ...
Страница 402: ...Chapter 33 802 1x Port based Network Access Control 402 Section VIII Port Security ...
Страница 404: ...404 Section IX Management Security ...
Страница 436: ...Chapter 36 PKI Certificates and SSL 436 Section IX Management Security ...
Страница 454: ...Chapter 38 TACACS and RADIUS Protocols 454 Section IX Management Security ...
Страница 462: ...Chapter 39 Management Access Control List 462 Section IX Management Security ...
Страница 504: ...Appendix B SNMPv3 Configuration Examples 504 Security Model Security Level Storage Type SNMPv3 Parameters Continued ...
Страница 532: ...Appendix D MIB Objects 532 ...