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 fail ed.
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 paired RoutingEngine 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 can 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 labeledMCS 0 and the RE 1 slot is
above the 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 standbymode and performs no functions.
By default, the master host module is the one with components installedin 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 t he JUNOSInternet
Software Configuration Guide: Getting Started.
The host module components are hot-pluggable,as described in Field-Replaceable
Units (FRUs) on page 4. Removal or failure of one or both components in the
standby host module doesnot affect router function. If one or bothcomponents
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,packet forwarding halts until both the Routing
Engine and MCS are reinstalledand functioning normally.
If thereare two host modules, the effect depends on the software configuration:
If the Routing Engines arerunning JUNOS Release 6.0 or later and
are configured for gracefulswitchover, the standby RoutingEngine
automaticallyassumes mastership without interruption of forwarding
performance. For informationabout configuring graceful switchover, see
the section about Routing Engineredundancy in JUNOS Internet Software
Configuration Guide: Getting Started.
Otherwise, forwarding halts while standby host module becomes the
master and the new master RoutingEngine resets the Packet Forwarding
Engine.
22 Host Module