How The Backup Center Works - 3Com MSR 50 Series Configuration Manual

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HAPTER ACKUP
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How the Backup Center
Works
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ENTER ONFIGURATION
When a dialer interface acts as the PPPoE client and the PPPoE session works in
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permanent on-line mode, it can be configured as the main interface.
When a BRI interface is used for the ISDN leased line, it can be configured as
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the main interface.
Backup interface
Backup interfaces are those functioning as backups for main interfaces (For
example, interfaces Serial 2/1 and Serial 2/2 in
idle. A backup interface can be any physical interface.
One backup interface can only back up one main interface.
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One main interface can be configured up to three backup interfaces.
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Up to 10 main interfaces can be configured on a device at one time.
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The following is how the backup center works:
Interface backup
As shown in Figure
and interfaces Serial 2/1 and Serial 2/2 act as the backup interfaces.
Figure 579 Diagram for main/backup mode
S2/0
Router A
In interface backup mode, at any given time, only one interface takes on data
transmission.
When the main interface is operating normally, even if the traffic is overloaded,
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the backup interface is in a backup state. All traffics are transmitted through
the main interface.
Only when the main interface cannot transmit data because of interface
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failure, the backup interface with a higher priority will take the main interface
instead and take on all traffic transmission.
After the failed main interface restores, data transmission will be switched over
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to the main interface. At any given time, only one interface takes on data
transmission.
Load sharing
As shown in Figure
interface, and interfaces Serial 2/1 and Serial 2/2 act as the backup interfaces.
579, interface Serial 2/0 on Router A acts as the main interface
100%
580, interface Serial 2/0 on Router A acts as the main
Figure 578), which are generally
Router B
LAN