Iccp; Stateful Line Module Switchover Modes; Stateless Switchover Mode; High Availability Mode - Juniper JUNOSE SOFTWARE FOR E SERIES 11.3.X - SERVICE AVAILABILITY CONFIGURATION GUIDE 2010-10-08 Configuration Manual

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Stateful Line Module Switchover Modes

Stateless Switchover Mode

High Availability Mode

Copyright © 2010, Juniper Networks, Inc.
module is disabled. The disabled line module during unified ISSU is cold booted after
the unified ISSU operation is complete. Only the primary line module participates in the
unified ISSU operation.
Interchassis Communication Protocol (ICCP) is used to establish communication sessions
between line modules that are configured for stateful switchover (configured in the high
availability pair). Controller events are generated for existing sessions on the line modules
with a notification about the session establishment and session teardown. The
applications that are running on the SRP module with ICC sessions formed between the
SRP and line modules are notified with the controller events after a stateful line module
switchover occurs.
The line module high availability manager resides on the SRP module to enable the
stateful switchover from a failed primary module to the secondary module in a high
availability pair of devices. The high availability manager interacts with its peer agent on
the line modules using ICC session and control bus. After the modules in a high availability
pair become operational in primary and secondary modes, the high availability manager
notifies interchassis controller (ICC) to enable ICC communication between the line
modules.
Stateful Line Module Switchover Modes on page 83
Stateful Line Module Switchover States on page 84
Activating High Availability on page 88
Deactivating High Availability on page 89
The line modules can operate in one of two redundancy modes—stateless switchover
and high availability.
Stateless switchover is the default behavior mode for E120 and E320 routers that contain
redundant line modules. This mode is available on line modules that you configured to
function in a redundancy group and on which the high availability behavior is not enabled
using the mode high-availability slot command. During switchover, the line, circuit, and
IP interfaces on one or more IOAs appear to go down temporarily. The duration of the
downtime depends on the number of interfaces and the size of the routing table, because
the router must reload the interface configuration and the routing table from the SRP
module.
The high availability mode uses an initial bulk file transfer and subsequent,
transaction-based mirroring to ensure rapid line module recovery after a switchover. This
process is referred to as stateful line module switchover.
Chapter 4: Managing Stateful Line Module Switchover
83