AT-S63 Management Software Features Guide
Section V: Spanning Tree Protocols
259
The same is true for any ports connected to bridges running the single-
instance spanning tree STP or RSTP. Those ports are also considered as
part of another region.
Each MSTI functions as an independent spanning tree within a region.
Consequently, each MSTI must have a root bridge to locate physical loops
within the spanning tree instance. An MSTI’s root bridge is called a
regional root
. The MSTIs within a region may share the same regional root
or they can have different regional roots.
A regional root for an MSTI must be within the region where the MSTI is
located. An MSTI cannot have a regional root that is outside its region.
A regional root is selected by a combination of the
MSTI priority
value and
the bridge’s MAC address. The MSTI priority is analogous to the RSTP
bridge priority value. Where they differ is that while the RSTP bridge
priority is used to determine the root bridge for an entire bridged network,
MSTI priority is used only to determine the regional root for a particular
MSTI.
The range for this parameter is the same as the RSTP bridge priority; from
0 to 61,440 in sixteen increments of 4,096. To set the parameter, you
specify the increment that represents the desired MSTI priority value.
Table 75 on page 241
lists the increments.
Region
Guidelines
Following are several points to remember about regions.
A network can contain any number of regions and a region can contain
any number of AT-9400 Switches.
The AT-9400 Switch can belong to only one region at a time.
A region can contain any number of VLANs.
All of the bridges in a region must have the same configuration name,
revision level, VLANs, and VLAN to MSTI associations.
An MSTI cannot span multiple regions.
Each MSTI must have a regional root for locating loops in the instance.
MSTIs can share the same regional root or have different roots. A
regional root is determined by the MSTI priority value and a bridge’s
MAC address.
The regional root of a MSTI must be in the same region as the MSTI.
Summary of Contents for AT-S63
Page 14: ...Figures 14 ...
Page 18: ...Tables 18 ...
Page 28: ...28 Section I Basic Operations ...
Page 58: ...Chapter 1 Overview 58 ...
Page 76: ...Chapter 2 AT 9400Ts Stacks 76 Section I Basic Operations ...
Page 96: ...Chapter 5 MAC Address Table 96 Section I Basic Operations ...
Page 114: ...Chapter 8 Port Mirror 114 Section I Basic Operations ...
Page 116: ...116 Section II Advanced Operations ...
Page 146: ...Chapter 12 Access Control Lists 146 Section II Advanced Operations ...
Page 176: ...Chapter 14 Quality of Service 176 Section II Advanced Operations ...
Page 196: ...196 Section III Snooping Protocols ...
Page 204: ...Chapter 18 Multicast Listener Discovery Snooping 204 Section III Snooping Protocols ...
Page 216: ...Chapter 20 Ethernet Protection Switching Ring Snooping 216 Section III Snooping Protocols ...
Page 218: ...218 Section IV SNMPv3 ...
Page 234: ...234 Section V Spanning Tree Protocols ...
Page 268: ...268 Section VI Virtual LANs ...
Page 306: ...Chapter 27 Protected Ports VLANs 306 Section VI Virtual LANs ...
Page 320: ...320 Section VII Internet Protocol Routing ...
Page 360: ...Chapter 30 BOOTP Relay Agent 360 Section VII Routing ...
Page 370: ...Chapter 31 Virtual Router Redundancy Protocol 370 Section VII Routing ...
Page 372: ...372 Section VIII Port Security ...
Page 402: ...Chapter 33 802 1x Port based Network Access Control 402 Section VIII Port Security ...
Page 404: ...404 Section IX Management Security ...
Page 436: ...Chapter 36 PKI Certificates and SSL 436 Section IX Management Security ...
Page 454: ...Chapter 38 TACACS and RADIUS Protocols 454 Section IX Management Security ...
Page 462: ...Chapter 39 Management Access Control List 462 Section IX Management Security ...
Page 532: ...Appendix D MIB Objects 532 ...