Users Guide

Stacking 265
Switch Stack MAC Addressing and Stack Design Considerations
The switch stack uses the MAC addresses assigned to the management unit
in the stack.
If the backup unit assumes control due to a management unit in the stack
failure or warm restart, the backup unit continues to use the MAC addresses
of the original management unit in the stack. This reduces the amount of
disruption to the network because ARP and other Layer-2 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
redundant 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 removing the management unit in the stack from a stack for use in a
different place in the network, make sure to power down the whole stack
before redeploying the management unit in the stack so that the stack
members do not continue to use the MAC address of the redeployed primary
switch.
iSCSI Connections
LLDP List of interfaces with MED devices attached
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 management unit in the stack.
Table 8-1. Applications that Checkpoint Data
Application Checkpointed Data