Dell PowerConnect 7048P User Manual - Page 162
NSF in the Data Center, Data Center Stack Topology
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NSF in the Data Center Figure 8-12 illustrates a data center scenario, where the stack of two PowerConnect switches acts as an access switch. The access switch is connected to two aggregation switches, AS1 and AS2. The stack has a link from two different units to each aggregation switch, with each pair of links grouped together in a LAG. The two LAGs and link between AS1 and AS2 are members of the same VLAN. Spanning tree is enabled on the VLAN. Assume spanning tree selects AS1 as the root bridge. Assume the LAG to AS1 is the root port on the stack and the LAG to AS2 is discarding. Unit 1 is the Management Unit. If unit 1 fails, the stack removes the Unit 1 link to AS1 from its LAG. The stack forwards outgoing packets through the Unit 2 link to AS1 during the failover. During the failover, the stack continues to send BPDUs and LAG PDUs on its links on Unit 2. The LAGs stay up (with one remaining link in each), and spanning tree on the aggregation switches does not see a topology change. Figure 8-12. Data Center Stack Topology AS1 LAG1 AS2 Unit 1 LAG2 Unit 2 162 Managing a Switch Stack
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1,216
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1,217
-
1,218
-
1,219
-
1,220
-
1,221
-
1,222
-
1,223
-
1,224
-
1,225
-
1,226
-
1,227
-
1,228
-
1,229
-
1,230
-
1,231
-
1,232
-
1,233
-
1,234