Juniper QFX3000-G QFabric, Deployment Manual, Page: 95 / 652

•
You cannot map unicast forwarding classes to multidestination fabric fc-sets.
• You cannot configure CoS for fabric fc-sets. (However, default CoS scheduling
properties are applied to traffic on the fabric, and the fabric interfaces use link layer
flow control (LLFC) for flow control.)
Fabric Forwarding Class Set Scheduling (CoS)
Although fabric fc-set CoS is not user-configurable, CoS is applied to traffic on the fabric.
(In addition, fabric interfaces use LLFC to ensure lossless transport for lossless traffic
flows.) This section describes how the fabric applies CoS scheduling to traffic:
• Class Groups for Fabric Forwarding Class Sets on page 69
• Class Group Scheduling on page 69
•
QFabric System CoS on page 71
Class Groups for Fabric Forwarding Class Sets
To transport traffic across the fabric, the QFabric system organizes the fabric fc-sets into
three classes called
class groups . The three class groups are:
• Strict-high priority —All traffic in the fabric fc-set
fabric_fcset_strict_high
. This class
group includes the traffic in
strict-high
priority and
network-control
forwarding classes
and in any forwarding classes you create on a Node device that consist of strict-high
priority or network-control forwarding class traffic.
• Unicast —All traffic in the fabric fc-sets fabric_fcset_be , fabric_fcset_noloss1 , and
fabric_fcset_noloss2 . This class group includes the traffic in the best-effort , fcoe , and
no-loss forwarding classes and in any forwarding classes you create on a Node device
that consist of best-effort or lossless traffic. If you use any of the hidden no loss fabric
fc-sets (
fabric_fcset_noloss3 , fabric_fcset_noloss4 , fabric_fcset_noloss5 , or
fabric_fcset_noloss6 ), that traffic is part of this class group.
•
Multidestination —All traffic in the fabric fc-set
fabric_fcset_multicast1
. This class group
includes the traffic in the
mcast
forwarding class and in any forwarding classes you
create on a Node device that consist of multidestination traffic. If you use any of the
hidden multidestination fabric fc-sets (
fabric_fcset_multicast2
,
fabric_fcset_multicast3
,
or
fabric_fcset_multicast4
), that traffic is also classified as part of this class group.
Class Group Scheduling
You cannot configure CoS for class groups or for fabric fc-sets (that is, you cannot attach
a traffic control profile to a fabric fc-set—you attach traffic control profiles to Node device
fc-sets to apply scheduling to the traffic that belongs to the Node device fc-set). By
default, the fabric uses weighted round-robin (WRR) scheduling in which each class
group receives a portion of the total available fabric bandwidth based on its type of traffic,
as shown in
Table 10 on page 70 :
69 Copyright © 2015, Juniper Networks, Inc.
Chapter 4: Software Features