Using Persistent Backup Connections; Comparing Demand Routing And Persistent Backup; Connections - HP ProCurve Secure Router 7203 dl Advanced Management And Configuration Manual

Configuring Backup WAN Connections
Determining a Backup Method
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If you use the backup ISDN modules, you cannot use MLPPP to aggregate
channels. The ISDN backup modules support bonding, rather than channel
aggregation. You can bond channels on an ISDN backup module only if:
you configure a persistent backup connection
the router connects to another ProCurve Secure Router
If both of these conditions are met, you can use bonding to increase band-
width.
If you use demand routing with a backup ISDN module, you can neither bond
nor multilink channels.

Using Persistent Backup Connections

You can also configure the backup module so that it immediately establishes
a dial-up connection when the primary interface fails. This connection stays
up until the primary interface is available again. You may want to configure
this type of backup connection between offices that require a constant con-
nection.
The ProCurve Secure Router provides some settings to control when a persis-
tent backup connection is established. For example, you can prevent the
connection from becoming active on weekends or evenings.
As mentioned earlier, when you configure a persistent backup connection,
you can bond two B channels for a total of 128 Kbps. The only limitation is
that the router must connect to another ProCurve Secure Router. If you want
to use MLPPP to aggregate channels, you must purchase and use a two-port
ISDN module, as described in Chapter 8: Configuring Demand Routing for
Primary ISDN Modules in the Basic Management and Configuration Guide.

Comparing Demand Routing and Persistent Backup

Connections

Table 3-1 lists the main differences between demand routing and persistent
backup connections.