Information About Policy Types
The device supports a number of policy types. You create class maps in the policy types.
There are three policy types:
-
Network-qos
-
Queuing
-
QoS
Before you enable FCoE on the Cisco Nexus device, you must enable class-fcoe in the three types of qos policies (network QoS, queuing, and QoS) by entering the type qos policy maps command and applying at least one FCoE QoS policy under system QoS.
The following QoS parameters can be specified for each type of class:
-
Type network-qos—A network-qos policy is used to instantiate system classes and associate parameters with those classes that are of system-wide scope.
-
Classification—The traffic that matches this class are as follows:
-
QoS Group—A class map of type network-qos identifies a system class and is matched by its associated qos-group.
-
-
Policy—The actions that are performed on the matching traffic are as follows:
Note
A network-qos policy can only be attached to the system QoS target.
-
MTU—The MTU that needs to be enforced for the traffic that is mapped to a system class. Each system class has a default MTU and the system class MTU is configurable.
-
Multicast optimization—This configuration specifies if the performance of multicast traffic mapped to this class will be optimized.
-
Pause no-drop—No drop specifies lossless service for the system class. Drop specifies that tail drop is used (arriving packets are dropped when the queue reaches its allocated size) when a queue for this system class is full.
An additional parameter pfc-cos can be configured. This parameter identifies the class of service (CoS) values to assert priority flow control (PFC) when traffic for a no-drop system class is not mapped based purely on CoS experiences congestion.
-
You can change the buffer for the no-drop class.
-
Queue Limit—This configuration specifies the number of buffers that need to be reserved to the queues of this system class. This option is not configurable for no-drop system classes.
-
-
-
Type queuing—A type queuing policy is used to define the scheduling characteristics of the queues associated with system classes.
Note
Some configuration parameters when applied to an EtherChannel are not reflected on the configuration of the member ports.
-
Classification—The traffic that matches this class are as follows:
-
QoS Group—A class map of type queuing identifies a system class and is matched by its associated QoS group.
-
-
Policy—The actions that are performed on the matching traffic are as follows:
Note
These policies can be attached to the system qos target or to any interface. The output queuing policy is used to configure output queues on the device associated with system classes. The input queuing policy is used to configure scheduling for queues in the CNA. The input queuing policy parameters are signaled to the CNA over the DCBX protocol.
-
Bandwidth—Sets the guaranteed scheduling deficit weighted round robin (DWRR) percentage for the system class.
-
Priority—Sets a system class for strict-priority scheduling. Only one system class can be configured for priority in a given queuing policy.
Note
-
The shaping feature is not supported in the Cisco Nexus 5000 and 6000 Series Switches.
-
It is recommended that you do not set the default class as priority class.
-
When a priority class is configured on the system, and the traffic from HIF towards the network interface (NIF) on FEX matches the priority class, there is a probability of packet drops even though the traffic is classified as priority. These packet drops can occur when there is congestion on the NIF interface. This limitation is applicable for Cisco Nexus 2232P and 2248PQ FEX devices.
-
-
-
Type qos—A type qos policy is used to classify traffic that is based on various Layer 2, Layer 3, and Layer 4 fields in the frame and to map it to system classes.
Note
Some configuration parameters when applied to an EtherChannel are not reflected on the configuration of the member ports.
-
Classification—The traffic that matches this class are as follows:
-
Access Control Lists—Classifies traffic based on the criteria in existing ACLs.
-
Class of Service—Matches traffic based on the CoS field in the frame header.
-
DSCP—Classifies traffic based on the Differentiated Services Code Point (DSCP) value in the DiffServ field of the IP header.
-
IP Real Time Protocol—Classifies traffic on the port numbers used by real-time applications.
-
Precedence—Classifies traffic based on the precedence value in the type of service (ToS) field of the IP header.
-
Protocol—Classifies traffic based on the IPv4 Protocol field or the IPv6 Next Header field of the IP header.
Note
The applied type qos policies must have the corresponding classes defined in the type network-qos policy.
-
-
Policy—The actions that are performed on the matching traffic are as follows:
Note
This policy can be attached to the system or to any interface. It applies to input traffic only.
Note
When you apply a type qos service policy on a FEX fabric port, it is not rejected. However, the type QoS service policy is never applied.
-
QoS Group—Sets the QoS group that corresponds to the system class this traffic flow is mapped to.
-
-