Service ingress QoS policies

Service ingress QoS policies define ingress service forwarding class queues and map flows to those queues. When a service ingress QoS policy is created by default, it always has two queues defined that cannot be deleted: one for the default unicast traffic and one for the default multipoint traffic. These queues exist within the definition of the policy. The queues only get instantiated in hardware when the policy is applied to a SAP. In the case where the service does not have multipoint traffic, the multipoint queues are not instantiated.

In the simplest service ingress QoS policy, all traffic is treated as a single flow and mapped to a single queue, and all flooded traffic is treated with a single multipoint queue. The required elements to define a service ingress QoS policy are:

a unique service ingress QoS policy ID
a QoS policy scope of template or exclusive
at least one default unicast forwarding class queue. The parameters that can be configured for a queue are discussed in Queue parameters.
at least one multipoint forwarding class queue

Optional service ingress QoS policy elements include:

additional unicast queues up to a total of 31
additional multipoint queues up to 31
QoS policy match criteria to map packets to a forwarding class

To facilitate more forwarding classes, subclasses are supported. Each forwarding class can have one or multiple subclass associations for SAP ingress classification purposes. Each subclass retains the chassis-wide behavior defined to the parent class while providing expanded ingress QoS classification actions.

There can be up to 64 classes and subclasses combined in a sap-ingress policy. With the extra 56 values, the size of the forwarding class space is more than sufficient to handle the various combinations of actions.

Forwarding class expansion is accomplished through the explicit definition of sub-forwarding classes within the SAP ingress QoS policy. The CLI mechanism that creates forwarding class associations within the SAP ingress policy is also used to create subclasses. A portion of the subclass definition directly ties the subclass to a parent, chassis-wide forwarding class. The subclass is only used as a SAP ingress QoS classification tool; the subclass association is lost when ingress QoS processing is finished.

When configured with this option, the forwarding class and drop priority of incoming traffic are determined by the mapping result of the EXP bits in the top label. Table: Forwarding class and enqueuing priority classification hierarchy based on rule type lists the classification hierarchy based on rule type.

Table: Forwarding class and enqueuing priority classification hierarchy based on rule type
#	Rule	Forwarding class	Enqueuing priority	Comments
1	default-fc	Set the policy’s default forwarding class.	Set to policy default	All packets match the default rule.
2	dot1p dot1p-value	Set when an fc-name exists in the policy. Otherwise, preserve from the previous match.	Set when the priority parameter is high or low. Otherwise, preserve from the previous match.	Each dot1p-value must be explicitly defined. Each packet can only match a single dot1p rule.
3	lsp-exp exp-value	Set when an fc-name exists in the policy. Otherwise, preserve from the previous match.	Set when the priority parameter is high or low. Otherwise, preserve from the previous match.	Each exp-value must be explicitly defined. Each packet can only match a single lsp-exp rule. This rule can only be applied on Ethernet L2 SAP.
4	prec ip-prec-value	Set when an fc-name exists in the policy. Otherwise, preserve from the previous match.	Set when the priority parameter is high or low. Otherwise, preserve from the previous match.	Each ip-prec-value must be explicitly defined. Each packet can only match a single prec rule.
5	dscp dscp-name	Set when an fc-name exists in the policy. Otherwise, preserve from the previous match.	Set when the priority parameter is high or low in the entry. Otherwise, preserve from the previous match.	Each dscp-name that defines the DSCP value must be explicitly defined. Each packet can only match a single DSCP rule.
6	IP criteria: multiple entries per policy Multiple criteria per entry	Set when an fc-name exists in the entry’s action. Otherwise, preserve from the previous match.	Set when the priority parameter is high or low in the entry action. Otherwise, preserve from the previous match.	When IP criteria is specified, entries are matched based on ascending order until first match, then processing stops. A packet can only match a single IP criteria entry.
7	MAC criteria: multiple entries per policy Multiple criteria per entry	Set when an fc-name exists in the entry’s action. Otherwise, preserve from the previous match.	Set when the priority parameter is specified as high or low in the entry action. Otherwise, preserve from the previous match.	When MAC criteria is specified, entries are matched based on ascending order until first match, then processing stops. A packet can only match a single MAC criteria entry.