Cpu Queues; Forwarding Classes; Table 16: Forwarding Classes; High-1 H1 - Alcatel-Lucent 7210 SAS E OS Quality Of Service Manual

QoS Overview

CPU Queues

The packets that are destined to the CPU are prioritized based on the application. Some of the
applications that are prioritized are Layer 2 data packets (a copy of which is sent to CPU for MAC
learning), EFM, CFM, STP, LACP, ICMP, etc. The CPU provides eight queues from BE (0) to NC
(7). The packets destined to the CPU are classified internally and are put into the correct queue.
These packets are rate-limited to prevent DoS attacks. The software programs the classification
entries to identify these packets and assigns appropriate bandwdith and priority to them. It is not
configurable by the user.

Forwarding Classes

7210 SAS devices support multiple forwarding classes and class-based queuing, so the concept of
forwarding classes is common to all of the QoS policies.
Each forwarding class (also called Class of Service (CoS)) is important only in relation to the other
forwarding classes. A forwarding class provides network elements a method to weigh the relative
importance of one packet over another in a different forwarding class.
Queues are created for a specific forwarding class to determine the manner in which the queue
output is scheduled. The forwarding class of the packet, along with the in-profile or out-of-profile
state, determines how the packet is queued and handled (the per hop behavior (PHB)) at each hop
along its path to a destination egress point. 7210 SAS devices support eight (8) forwarding classes
(Table

Table 16: Forwarding Classes

FC-ID
7
6
5
4
3
Page 52
16).
FC Name
Designa-
tion
Network NC
Control
High-1
Expedited
High-2
Low-1
FC DiffServ
Name
NC2
H1 NC1
EF EF
H2 AF4
L1 AF2
7210 SAS E OS Quality of Service Guide
Notes
Intended for network control traffic.
Intended for a second network control
class or delay/jitter sensitive traffic.
Intended for delay/jitter sensitive traffic.
Intended for delay/jitter sensitive traffic.
Intended for assured traffic. Also is the
default priority for network management
traffic.