Dell PowerConnect 7048P Manual page 142

Powerconnect 7000 series stackable layer 2 and 3 switches

Hide thumbs Also See for PowerConnect 7048P:

Table of Contents

Checkpointing

Switch applications (features) that build up a list of data such as neighbors or

clients can significantly improve their restart behavior by remembering this

data across a warm restart. This data can either be stored persistently, as

DHCP server and DHCP snooping store their bindings database, or the

Management Unit can checkpoint this data directly to the standby unit.

Persistent storage allows an application on a standalone unit to retain its data

across a restart, but since the amount of storage is limited, persistent storage

is not always practical.

The NSF checkpoint service allows the Management Unit 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 data.

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

that the Management Unit has when it fails. For example, the Management Unit

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

Managing a Switch Stack

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