Unicast Traffic; Figure 2-4 Switch Fabric Interconnections - Cisco ASR 9000 series Reference Manual

Chapter 2 Functional Description
Figure 2-4 Switch Fabric Interconnections
Local fabric interface
chip connects route
processor to fabric
RP
FIC
RSP 0
RSP 1
FIC
RP

Unicast Traffic

Unicast traffic through the switch is managed by a VOQ scheduler chip. The VOQ scheduler ensures that
a buffer is available at the egress of the switch to receive a packet before the packet can be sent into the
switch. This mechanism ensures that all ingress line cards have fair access to an egress card, no matter
how congested that egress card may be.
The VOQ mechanism is an overlay, separate from the switch fabric itself. VOQ arbitration does not
directly control the switch fabric, but ensures that traffic presented to the switch will ultimately have a
place to go when it exits the switch, preventing congestion in the fabric.
The VOQ scheduler is also one-for-one redundant, with one VOQ scheduler chip on each of the two
redundant RSP cards.
OL-17501-01
D R A F T — C I S C O C O N F I D E N T I A L
Each path is
nominally 20 Gbps,
double line is 40 Gbps
Fabric
Chip
Fabric
Chip
Fabric
Chip
Fabric
Chip
Cisco ASR 9000 Aggregation Services Router Overview and Reference Guide
Line cards connect to two
primary and two redundant
paths, for 40 Gbps total bandwidth
Line Card
FIC
(LC 0)
Series Router
Line Card
FIC
(LC 3)
Line Card
FIC
(LC 4)
Line Card
FIC
(LC 7)
Route Switch Processor Card
ASR 9006
ASR 9010
Series Router
2-9