JUNOS Internet Software Network Operations Guide: Hardware
546 ! Understanding Redundant SIBs
The following sections describe SIB redundancy on various routing platforms:
! M320 Router SIBs on page 546
! T320 Router SIBs on page 546
! T640 Routing Node SIBs on page 546
M320 Router SIBs
Four SIBs are installed in the M320 router. The SIBs are located at the center rear of
the chassis in the slots labeled
SIB0 through SIB3 (top to bottom). (See Figure 225
on page 545.) All four SIBs are active, and there is no backup.
T320 Router SIBs
Three SIBs are installed in the router. The SIBs are located at the center rear of the
chassis in the slots labeled
SIB0 through SIB2. (See Figure 225 on page 545.)
Each FPC has a dedicated ASIC with five high-speed links that connect to the SIBs.
Two high-speed links connect to
SIB1 and SIB2. One high-speed link connects to
SIB0. SIB0 acts as a backup to SIB1 and SIB2. In the event of a complete SIB failure,
SIB0 will become active. Because SIB0 has only one high-speed link to each FPC,
only three links will remain active. A slight degradation in forwarding capacity may
occur. When the failed SIB is replaced, it will become active and
SIB0 will revert to
backup. The router will regain full forwarding capacity.
T640 Routing Node SIBs
Five SIBs are installed in the routing node. The SIBs are located at the center rear of
the chassis in the slots labeled
SIB0 through SIB4 (top to bottom). (See Figure 225
on page 545.)
Each FPC1 and FPC2 has a dedicated ASIC with five high-speed links that connect
to the SIBs (one link per SIB). An FPC3 has two dedicated ASICs, and each ASIC has
five high-speed links that connect to the SIBs (a total of 10 links). One of the five
SIBs—usually
SIB4—acts as a backup to the remaining four SIBs. In the event of a
SIB failure, the backup SIB becomes active and traffic forwarding continues without
any degradation. When the failed SIB is replaced, it becomes the new backup.
The SIBs are hot-insertable and hot-removable.
See Also ! Monitoring the Host Subsystem on page 289
! Monitoring the SIBs on page 325
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