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Understanding QoS Configuration on the Matrix N-Series
discarding traffic imposed by rate limiting, delays are induced into its transmission by retaining
the data for future transmission. However, the delays must also be bounded to the degree that the
traffic is sensitive to delays.
Understanding QoS Configuration on the Matrix N-Series
This section discusses the six components for configuring QoS and displaying QoS status on an
N‐Series switch router:
CoS Port‐Type: Determines the transmit queue (TxQ) and Inbound Rate Limiting (IRL) resource
capabilities of the ports in your system. Knowledge of these capabilities is important when
configuring queue behaviors. Port group membership and the port resources available are
determined by port type.
CoS Port Groups: Provide for the grouping of ports by the same class of service features and port
type.
CoS Port Resource Table: Enables the association of rate limiter and rate shaper values to a port.
CoS Reference Mapping Table: Maps your defined TxQ and IRL index references, used by the
CoS settings table, to the physical queue and rate limiter settings created in the port‐resource
table.
CoS Settings Table: Used for CoS parameter assignment and contains the current settings for each
class of service feature. Each class of service entry consists of an entry index, an 802.1p priority, an
optional ToS value, a transmit queue reference, and an optional IRL reference.
CoS State: A global setting that must be enabled for a configured CoS to affect port behavior.
When enabled, CoS state associated with a port supersedes current default or modified port‐level
controls for priority queue mapping, port rate limiting, and transmit queue. When disabled the
port settings apply.
Numerous QoS values are associated with each other through reference. With the exception of
802.1p priority and ToS, CoS values are first mapped to a port group, which associates a CoS
configuration with a port type. A port group has the following CoS parameters associated with it:
•
Physical port(s)
•
Strict or weighted fair queuing behavior
•
Rate‐limit setting(s)
•
Rate‐shaping setting(s)
•
A port queue
•
A port reference
Understanding how these parameters are first mapped to the port group and then to a TxQ or IRL
reference is the key to understanding QoS configuration. Where appropriate, the task column in
Procedure 1 on page
See "Determining CoS Port‐Type" on page 10 and "Configuring CoS Port Groups" on page
a port group discussion.
February 22, 2008
Note: It is recommended that you use Enterasys NetSight Policy Manager as an alternative to CLI
for configuring policy-based CoS on the Enterasys Matrix Series devices.
A policy discussion is outside the scope of this document and will be limited to the relevant
configuration example commands.
21 identifies these mapping relationships.
11 for
Page 9 of 29
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