Cisco WS-X6416-GE-MT - Interface Module - Expansion Instrukcja Użytkownika Pobierz pdf (Strona 38)

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Software MQC syntax described above. In this example, the function of using an ACL for trusting

the CoS on all traffic coming into port gigabit 3/1 is compared.

Cisco Catalyst OS Cisco IOS Software

set qos acl ip CatOS trust-cos any

commit qos acl CatOS

set qos acl map CatOS 3/1

access-list 101 permit ip any any

policy-map IOS

class IOS access-group 101

trust cos

interface gigabitethernet 3/1

service-policy input IOS

When a Cisco Catalyst OS ACL is created, modified, or deleted, the changes exist temporarily in

an edit buffer in memory. The Cisco Catalyst OS requires that the ACL be committed for it to take

effect. Cisco IOS Software does not utilize the edit buffer concept. After a policy has been built in

Cisco IOS Software, it must then be mapped to either a port or a VLAN for that policy to take

effect. When a policy is mapped to an “up” interface, the ASIC hardware is programmed with the

necessary information and that policy is in effect.

Policers

The policing function is primarily used for rate limiting traffic to a configured speed. If traffic

exceeds the configured speed, then it can either be dropped or marked down to a lower priority.

This is useful to help ensure compliance to service level agreements or for security protection. The

policer can either be an aggregate or a microflow policer. An aggregate policer will rate limit all

traffic in a class or group of classes to one combined (or aggregate) rate. A microflow policer will

rate limit each flow (a unique SA/DA MAC address, SA/DA IP address, TCP/UDP port numbers,

and with UBRL, a unique SA or DA) in a traffic class to an individual rate. A total of 63 microflows

and 1023 aggregates can be configured per chassis (independent of the operating system).

In the Cisco Catalyst OS, the policing parameters, such as rate, burst, and related actions, are

defined first in a policer statement. A QoS ACL is configured which identifies both the traffic to-be-

policed and references the appropriate policer. Then, the QoS ACL needs to be committed and

applied to a port or VLAN, as with normal ACL configuration.

In Cisco IOS Software, the ACL is defined first. The policing parameters are defined in one of two

configuration modes. This depends on the type of policer being implemented; differences are

discussed in the following sections.

Aggregate Policers

There are two forms of aggregate policers that can be defined in the Cisco Catalyst OS: Shared

Aggregate Policers and Per-Interface Aggregate Policers.

Shared Aggregate Policers (sometimes referred to as Named Aggregate Policers) are applied to

a group of interfaces/VLANs and provide the function of policing traffic across all interfaces and/or

classes cumulatively. As an example, use the shared aggregate policer when a 100-Mbps rate

limit should be applied to four different interfaces combined.These policers are supported in both

the Cisco Catalyst OS and Cisco IOS Software. The following table shows a configuration

comparison of both implementations:

1 2 ... 33 34 35 36 37 38 39 40 41 42 43 ... 50 51

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