This section describes the allocation of QoS resources for network QoS policies of the ip-interface and port type.
When an IP interface is created, a default network QoS policy of the ip-interface type is applied. For the default policy, two meters and two classification entries in hardware are allocated.
The resources are allocated to a network policy only when a port is configured for the IP interface. When a network port is configured, a default network QoS policy of the port type is applied.
For every FC in use, the system allocates two classification entries in hardware, provided the FC is configured to use both the unicast meter and multicast meter, or provided the default meter 9 is configured in the policy. If multiple match criteria entries map to the same FC, each of these are allocated two classification entries in hardware; for example, if there are two match-criteria entries that map to FC ‟af,” a total of four classification entries are allocated in hardware, and if there are four match-criteria entries that map to FC ‟af,” a total of eight classification entries are allocated in hardware.
For every meter or policer in use, the system allocates one meter in hardware. A meter or policer is considered in use when it is associated with an FC in use.
The number of IP interfaces and network ports allowed is limited by the number of classification resources available in hardware, subject to the system limit on the number of IP interfaces and network or hybrid ports supported by the system.
To calculate the number of QoS resources used by an IP interface, determine the following items:
number of match-criteria entries used to identify the FC
number of FCs to use
Only the FCs used by the match-criteria classification entries are considered in the ‟number of FCs” and are therefore are referred to as ‟FCs in use”. In network policies of the ip-interface type, a default multipoint meter 9 is created in a policy; for policies of the port type, a default multipoint meter needs to be explicitly configured by the user, if required.
Use the following rules to compute the number of classification entries per FC in use:
If an FC is in use and is created without explicit meters, use default meter 1 for unicast traffic and default meter 9 (if configured) for all other traffic types (that is, broadcast, multicast, and unknown-unicast). This requires two classification entries in hardware. If default multipoint meter 9 is not configured, the FC uses the unicast meter for all traffic types. In this case, the FC requires a single classification entry in hardware.
If an FC is in use and is created with an explicit unicast meter, use that meter for unicast traffic and use default meter 9 (if configured) for all other traffic types. This requires two classification entries in hardware. If default multipoint meter 9 is not configured, the FC uses the unicast meter for all traffic types. In this case, the FC requires a single classification entry in hardware.
If an FC is in use and is created with an explicit unicast meter and explicit multicast meter, use the unicast meter for unicast traffic and a multicast meter for all other kinds of traffic. This requires two classification entries in hardware.
Given the number of match criteria and the number of FCs in use, the following equation calculates the total number of classification entries (TC) per policy:
where:
E(i) is the number of match-criteria entries that classify packets to FCi. For the 7210 SAS platforms, the maximum number of classification entries per policy can be 64 (including default).
In the worst case, only 2 classification entries are used for each FC in a network policy, because only two types of traffic are supported.
Determine the number of policers or meters (TP) to use. A maximum of 16 meters per network policy are available.
The number of TPs used is the number of meters configured in the policy. Among that number, only those meters configured for use with an FC are considered during resource allocation. Meters that are created but not associated with an FC are not counted for resource allocation.