
BigIron RX Series Configuration Guide
1051
53-1002253-01
Chapter
40
Multiple Spanning Tree Protocol (MSTP) 802.1s
802.1s Multiple Spanning Tree Protocol
Multiple Spanning Tree Protocol (MSTP) as defined in IEEE 802.1s allows you to configure multiple
STP instances. This will allow several VLANs to be mapped to a reduced number of spanning-tree
instances. This ensures loop-free topology for 1 or more VLANs that have the same Layer 2
topology.
Multiple spanning-tree regions
Using MSTP, the entire network runs a common instance of RSTP. Within that common instance,
one or more VLANs can be individually configured into distinct regions. The entire network runs the
common spanning tree instance (CST) and the regions run a local instance. The local instance is
known as Internal Spanning Tree (IST). The CST treats each instance of IST as a single bridge.
Consequently, ports are blocked to prevent loops that might occur within an IST and also
throughout the CST. In addition, MSTP can coexist with individual devices running STP or RSTP in
the Common and Internal Spanning Trees instance (CIST). With the exception of the provisions for
multiple instances, MSTP operates exactly like RSTP.
For example, in
Figure 139
a network is configured with two regions, Region 1 and Region 2. The
entire network is running an instance of CST. Each of the regions is running an instance of IST. In
addition, this network contains Switch 1 running RSTP that is not configured in a region and
consequently is running in the CIST instance. In this configuration, the regions are each regarded
as a single bridge to the rest of the network, as is Switch 1. The CST prevents loops from occurring
across the network. Consequently, a port is blocked at port 1/2 of switch 4.
Additionally, loops must be prevented in each of the IST instances. Within the IST Region 1, a port is
blocked at port 1/2 of switch 4 to prevent a loop in that region. Within Region 2, a port is blocked at
port 3/2 of switch 3 to prevent a loop in that region.
Содержание BigIron RX Series
Страница 100: ...24 BigIron RX Series Configuration Guide 53 1002253 01 Logging on through the Web Management Interface 2 ...
Страница 192: ...116 BigIron RX Series Configuration Guide 53 1002253 01 Configuring authentication method lists 4 ...
Страница 228: ...152 BigIron RX Series Configuration Guide 53 1002253 01 Enabling WAN PHY mode support 6 ...
Страница 312: ...236 BigIron RX Series Configuration Guide 53 1002253 01 Displaying IP information 7 ...
Страница 356: ...280 BigIron RX Series Configuration Guide 53 1002253 01 Resetting LLDP statistics 9 ...
Страница 402: ...326 BigIron RX Series Configuration Guide 53 1002253 01 Transparent firewall mode 11 ...
Страница 432: ...356 BigIron RX Series Configuration Guide 53 1002253 01 SuperSpan 12 ...
Страница 500: ...424 BigIron RX Series Configuration Guide 53 1002253 01 MRP CLI example 14 ...
Страница 580: ...504 BigIron RX Series Configuration Guide 53 1002253 01 Configuring multicast traffic engineering 18 ...
Страница 591: ...BigIron RX Series Configuration Guide 515 53 1002253 01 Displaying traffic reduction 19 ...
Страница 592: ...516 BigIron RX Series Configuration Guide 53 1002253 01 Displaying traffic reduction 19 ...
Страница 598: ...522 BigIron RX Series Configuration Guide 53 1002253 01 Viewing Layer 2 ACLs 20 ...
Страница 656: ...580 BigIron RX Series Configuration Guide 53 1002253 01 Trunk formation 22 ...
Страница 754: ...678 BigIron RX Series Configuration Guide 53 1002253 01 Displaying RIP filters 24 ...
Страница 814: ...738 BigIron RX Series Configuration Guide 53 1002253 01 Displaying OSPF information 25 ...
Страница 932: ...856 BigIron RX Series Configuration Guide 53 1002253 01 Generalized TTL security mechanism support 26 ...
Страница 980: ...904 BigIron RX Series Configuration Guide 53 1002253 01 Clearing IS IS information 28 ...
Страница 1000: ...924 BigIron RX Series Configuration Guide 53 1002253 01 Using secure copy 30 ...
Страница 1088: ...1012 BigIron RX Series Configuration Guide 53 1002253 01 IP source guard 35 ...
Страница 1108: ...1032 BigIron RX Series Configuration Guide 53 1002253 01 Reading CDP packets 37 ...
Страница 1126: ...1050 BigIron RX Series Configuration Guide 53 1002253 01 Clearing sFlow statistics 39 ...
Страница 1140: ...1064 BigIron RX Series Configuration Guide 53 1002253 01 802 1s Multiple Spanning Tree Protocol 40 ...
Страница 1324: ...1248 BigIron RX Series Configuration Guide 53 1002253 01 Displaying OSPFv3 information 48 ...
Страница 1363: ...BigIron RX Series Configuration Guide 1287 53 1002253 01 Continuous System Monitor 51 ...
Страница 1364: ...1288 BigIron RX Series Configuration Guide 53 1002253 01 Continuous System Monitor 51 ...
Страница 1404: ...1328 BigIron RX Series Configuration Guide 53 1002253 01 Commands That Require a Reload D ...
Страница 1458: ...1382 BigIron RX Series Configuration Guide 53 1002253 01 VSRP E ...