Internet Router Hardware Guide

M160 Internet Router Hardware Guide
Table 7: States for SFM LEDs
Label Color State Description
On steadily SFM is functioning normally.OK
Green
Blinking
SFM is starting up.
FAIL Amber On steadily SFM has f ailed.
Host Module
The host module constructs routing tables, performs system management
functions, and generates the SONET/SDH clock signal for SONET/SDH interfaces. It
consists of a paire d Routing Engine and Miscellaneous Control Subsystem (MCS).
For a host module to function, both of its components—Routing Engine and
MCS—must be installed and operational. One or two host modules ca n be installed
into the midplane from the rear of the chassis, as shown in Figure 3: the Routing
Engine slot labeled
RE 0 is below the MCS slot labeled MCS 0 and the RE 1 slot is
above t he
MCS 1 slot.
If two host modules are installed, both are powered on, but only one is active (the
master); the second host module is in standby mode and performs no functions.
By default, the master host module is the one with components installed in the
RE 0 and MCS 0 slots. To change the default master Routing Engine, include the
appropriate
[edit chassis redundancy routing-engine] statement in the configuration, as
described in the section about Routing Engine redundancy in the JUNOS Internet
Software Configuration Guide: Getting Started.
The host module components are hot-pluggable, as d escribed in Field-Replaceable
Units (FRUs) on page 4. Removal or failure of one or both components in the
standby host module does not affect router function. If one or both components
in the master host module is removed from the chassis, the effect depends on
whether two host modules are installed:
If there is only one host module, p acket forwarding halts until both the Routing
Engine and MCS are reinstalled and functioning normally.
If there are two host modules, the effect depends on t he software configuration:
If the Routing Engines are running JUNOS Release 6.0 or later and
are configured for graceful switchover, the standby Routing Engine
automatically assumes mastership without interruption of forwarding
performance. For information about configuring graceful switchover, see
the section about Routing Engine redundancy in JUNOS Internet Software
Configuration Guide: Getting Started.
Otherwise, forwarding halts while standby host module becomes the
master and the new master Routing Engine resets the Packet Forwarding
Engine.
22 Host M odule