Technical Documentation
T640 Switch Interface Boards (SIBs) Description
The Switch Interface Boards (SIBs) provide the switching function to the destination FPC (see Figure 1).
The SIBs create the switch fabric for the router, providing up to a total of 640 million packets per second (Mpps) of forwarding. Five SIBs are installed in the router. The SIBs are located at the center rear of the chassis in the slots labeled SIB0 through SIB4 (top to bottom).
SIBs are hot-insertable and hot-removable.
One of the five SIBs—usually SIB4—acts as a backup to the remaining four SIBs. If a SIB fails, the backup SIB becomes active and traffic forwarding continues without any degradation. When the failed SIB is replaced, it becomes the new backup.
Each SIB consists of the following components:
- Switch Fabric ASICs.
- High-speed links (HSLs) to each FPC. See Table 1.
- Three LEDs—ACTIVE, OK, and FAIL—located on the SIB faceplate that display the status of the SIB. T640 Switch Interface Boards (SIBs) LEDs describes the functions of the SIB LEDs.
- SIB online/offline button, located on the SIB faceplate.
Each T640-SIB also has a fiber-optic adapter for connection
to a TX Matrix router. See the TX Matrix Router Hardware Guide 
.
Table 1: Links to the SIBs From the FPCs
FPC Type | Links to SIBs |
|---|---|
Type 1 FPC | Each FPC has one dedicated ASIC with five high-speed links that connect to the SIBs (one link per SIB) |
Type 2 FPC | Each FPC has one dedicated ASIC with five high-speed links that connect to the SIBs (one link per SIB) |
Type 3 FPC | Each FPC has two dedicated ASICs, and each ASIC has five high-speed links that connect to the SIBs (a total of 10 links). |
Type 4 FPC | Each FPC has one dedicated ASIC with ten high-speed links that connect to the SIBs (two links per SIB). |
The T640 router supports these types of SIBs:
- Standard SIB
- Standard SIB version B (supported in Junos OS Release
7.3 and later) is required to support the Enhanced Scaling FPCs in
a standalone T640 router. If you use one or more Enhanced Scaling
FPCs in a T640 router that is not part of a routing matrix, each SIB
in the router must be a SIB version B. All the SIBs in the T640
router can be either standard SIB or SIB version B. You cannot
use both on the same router at the same time.
Figure 1: Standard SIB and Standard SIB Version B
- The T640-SIB (supported in Junos OS Release 7.0 and later) is required to support T640 routers connected to a TX Matrix platform); see Figure 2. The T640 SIB supports the Enhanced Scaling FPC4 for T640 routers connected to a TX Matrix platform.
Figure 2: T640 SIB
