Dell M6220 User Configuration Manual page 155

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The NSF checkpoint service allows the stack master to communicate certain

data to the backup unit in the stack. When the stack selects a backup unit,

the checkpoint service notifies applications to start a complete checkpoint.

After the initial checkpoint is done, applications checkpoint changes to their

The switch cannot guarantee that a backup unit has exactly the same data

that the stack master has when it fails. For example, the stack master might fail

before the checkpoint service gets data to the backup if an event occurs shortly

before a failover.

Table 8-1 lists the applications on the switch that checkpoint data and

describes the type of data that is checkpointed.

Table 8-1. Applications that Checkpoint Data

Captive Portal

DHCP snooping

IGMP/MLD Snooping

Route Table Manager

Checkpointed Data

Dynamic ARP entries

Calls in progress

Authenticated clients

Address bindings (persistent)

DHCP bindings database

Internal VLAN assignments

Spanning tree port roles, port states, root bridge, etc.

Authenticated clients

Multicast groups, list of router ports, last query data for

Neighbor cache entries

List of interfaces with MED devices attached

Neighbors and designated routers

IPv4 and IPv6 dynamic routes

Managing a Switch Stack

M8024 M6348 M8024-k