Understanding CoS Forwarding Classes
It is helpful to think of forwarding classes as output queues. In effect, the end result of
classification is the identification of an output queue for a particular packet. For a classifier
to assign an output queue to each packet, it must associate the packet with one of the
following forwarding classes:
•
expedited-forwarding (ef)—Provides a low loss, low latency, low jitter, assured
bandwidth, end-to-end service.
•
assured-forwarding (af)—Provides a group of values you can define and includes four
subclasses: AF1, AF2, AF3, and AF4, each with two drop probabilities: low and high.
•
best-effort (be)—Provides no service profile. Loss priority is typically not carried in a
class-of-service (CoS) value.
•
network-control (nc)—Supports protocol control and thus is typically high priority.
•
multicast best-effort (mcast-be)—Used for high-priority multicast packets.
•
multicast assured-forwarding (mcast-af)—Provides two drop profiles, high and low,
for multicast packets.
•
multicast best-effort (mcast-be)—Provides no service profile for multicast packets.
NOTE:
The forwarding classes multicast expedited-forwarding, multicast
assured-forwarding, and multicast best-effort are applicable only to Juniper
Networks EX8200 Ethernet Switches.
Juniper Networks EX Series Ethernet Switches support up to 16 forwarding classes, thus
allowing granular packet classification. For example, you can configure multiple classes
of EF traffic such as EF, EF1, and EF2.
EX Series switches support up to eight output queues. Therefore, if you configure more
than eight forwarding classes, you must map multiple forwarding classes to single output
queues.
•
Default Forwarding Classes on page 3156
Default Forwarding Classes
Table 405 on page 3157 shows the four default forwarding classes defined for unicast
traffic, and Table 406 on page 3157 shows the three default forwarding classes defined
for multicast traffic.
NOTE:
The default forwarding classes for multicast traffic are applicable
only to EX8200 switches.
Copyright © 2010, Juniper Networks, Inc.
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Complete Software Guide for Junos
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OS for EX Series Ethernet Switches, Release 10.3
Summary of Contents for JUNOS OS 10.3 - SOFTWARE
Page 325: ...CHAPTER 17 Operational Mode Commands for System Setup 229 Copyright 2010 Juniper Networks Inc ...
Page 1323: ...CHAPTER 56 Operational Mode Commands for Interfaces 1227 Copyright 2010 Juniper Networks Inc ...
Page 2841: ...CHAPTER 86 Operational Commands for 802 1X 2745 Copyright 2010 Juniper Networks Inc ...
Page 3367: ...CHAPTER 113 Operational Mode Commands for CoS 3271 Copyright 2010 Juniper Networks Inc ...
Page 3435: ...CHAPTER 120 Operational Mode Commands for PoE 3339 Copyright 2010 Juniper Networks Inc ...
Page 3529: ...CHAPTER 126 Operational Mode Commands for MPLS 3433 Copyright 2010 Juniper Networks Inc ...