Juniper QFX3000-G QFabric, Deployment Manual, Page: 48 / 652

Figure 5: Clos Switching for QFX3008-I Interconnect Devices
IC0
F1
Incoming traffic
Outgoing traffic
Front Card Rear Card
F3
F2
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Traffic enters a QSFP+ port from a Node device, and an ingress chipset provides stage
F1 processing. For the F2 stage, the frame is sent to a rear card and processed by a
midplane chipset. Lastly, an egress chipset on the front card QSFP+ port handles
processing tasks for the F3 stage. At each of the three Clos stages, a switching table
chooses the best path and determines where to send the frame to reach the next stage.
The F1 and F3 stages can be handled by the same front card or different front cards,
depending on the best path selected by the fabric. After the frame traverses the
Interconnect device backplane, the Interconnect device sends the frame to the egress
Node device.
QFX3008-I Interconnect Devices
The QFX3008-I Interconnect device contains eight slots in the front of the chassis. In
each slot, you can install a front card containing 16 40-Gbps quad small form-factor
pluggable plus (QSFP+) ports. A fully configured system offers a total capacity of 128
QSFP+ connections. These front card ports attach to the high-speed backplane to reach
the eight slots in the rear of the chassis, which provide the heavy-duty interconnections
for the entire QFX3000-G QFabric system. In addition, four interfaces (two per Control
Board) provide Gigabit Ethernet access to the control plane management network.
Figure 6 on page 23 shows an example of the data plane and control plane connections
for QFX3008-I Interconnect devices.
Copyright © 2015, Juniper Networks, Inc. 22
QFX3000-G QFabric System Deployment Guide