High Availability Configured And Disabled On The Line Module; High Availability Configured And The Switchover State Is Active Or; Disabled; Rebooting Of The System When Line Module High Availability Is - Juniper JUNOSE SOFTWARE FOR E SERIES 11.3.X - SERVICE AVAILABILITY CONFIGURATION GUIDE 2010-10-08 Configuration Manual

JunosE 11.3.x Service Availability Configuration Guide

High Availability Configured and Disabled on the Line Module

High Availability Configured and the Switchover State Is Active or Disabled
Rebooting of the System When Line Module High Availability Is Configured

Stateful SRP Switchover

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When high availability is enabled on a router, the secondary module takes over the role
of the primary module, which causes normal system services and subscriber data traffic
to continue without interruption after a switchover. The system controller (SC) on E120
and E320 routers is referred to as the SRP module and the main processor in a line module
is called the interface controller (IC).
If line module high availability is configured and the state is not active, when a fault occurs
on the primary line module, the primary line module performs a cold switchover to a
secondary module. After the switchover, the secondary module starts operating as the
new primary module. The previously configured primary module, after it becomes
operational, takes over the role of the secondary module. Subscribers are disconnected
and need to log in again to establish their connections again. This behavior is similar to
the functionality experienced during the line module redundancy operation.
Any failure on the secondary line module or a restart of the module causes high availability
to move to the disabled state. The show redundancy line-card command displays the
HA status on all line modules in the system. When a line module transitions from one
state to another, log messages are seen on the SRP console and SNMP traps, if enabled,
are sent.
All CLI commands that cause the line module to cold restart behave in the same manner,
except for the method adopted to trigger the switchover action. For example, the reload
slot and slot disable commands that reload a primary line module, causing the secondary
module to take over as the primary. However, the slot erase command clears the
configurations on the line module that is fitted in that slot. If you erase the slot
configuration for a primary line module, both the primary and secondary line modules
that participate in HA are cold booted. If you erase the slot configuration for the secondary
line module, only that module is cold booted and the primary module is not cold booted.
If you enter the reload slot command, after booting up, line modules start operating in
HA mode. With the slot disable command, HA is disabled until you reenable the slot.
The line modules undergo a cold start, when the router is rebooted, and the secondary
line module is held in a state in which it is not online. The primary line module reaches
the online state. If the primary line module fails to come up online, within the specified
timeout value (of less than 8.5 minutes), the secondary line module takes over as the
primary module and HA remains in the disabled state.
During a stateful SRP switchover, a window of time occurs when the communication
between interface controllers (IC) is disrupted owing to the switchover to new SRP
module, which requires the Ethernet switch to relearn the MAC addresses and the
interchassis communication (ICC) sessions to be reestablished. The system infrastructure
ensures this task of relearning of details is transparent to the applications. Any notification
sent by the applications on the IC-IC communication is either buffered until the
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