DELL N3000 User Manual

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Managing a Switch Stack
181
Switch Stack MAC Addressing and Stack Design Considerations
The switch stack uses the MAC addresses assigned to the stack master. 
If the backup unit assumes control due to a stack master failure or warm 
restart, the backup unit continues to use the original stack master’s MAC 
addresses. This reduces the amount of disruption to the network because 
ARP and other L2 entries in neighbor tables remain valid after the failover to 
the backup unit.
Stack units should always be connected with a ring topology (or other 
biconnected topology), so that the loss of a single stack link does not divide 
the stack into multiple stacks. If a stack is partitioned such that some units 
lose all connectivity to other units, then both parts of the stack start using the 
same MAC addresses. This can cause severe problems in the network.
If you move the stack master to a different place in the network, make sure 
you power down the whole stack before you redeploy the stack master so that 
the stack members do not continue to use the MAC address of the redeployed 
switch. 
NSF Network Design Considerations
You can design your network to take maximum advantage of NSF. For 
example, by distributing a LAG's member ports across multiple units, the 
stack can quickly switch traffic from a port on a failed unit to a port on a 
OSPFv2
Neighbors and designated routers
OSPFv3
Neighbors and designated routers 
Route Table Manager
IPv4 and IPv6 dynamic routes
SIM
The system's MAC addresses. System up time. IP address, 
network mask, default gateway on each management 
interface, DHCPv6 acquired IPv6 address.
Voice VLAN
VoIP phones identified by CDP or DHCP (not LLDP)
NOTE: 
Each switch is assigned four consecutive MAC addresses. A stack of 
switches uses the MAC addresses assigned to the stack master.
Table 9-1. Applications that Checkpoint Data
Application
Checkpointed Data