Cisco WS-X6708-10G-3CXL= - 10 Gigabit Ethernet Module Manual de usuario descargar pdf (Pagina 58)

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There are two forms of aggregate policers:

●

Per-interface aggregate policers: These policers are applied to an individual interface using the police

command within a policy-map class. You can apply these map classes to multiple interfaces, but the policer

polices each interface separately.

●

Named aggregate policers or shared aggregate: These policers are applied to a group of ports and police

traffic across all interfaces cumulatively. Name aggregates are applied using the mls qos aggregate police

command.

The policing function is typically handled by the ingress forwarding engine (either PFC or DFC). A critical res triction to

implementing aggregate policers in a Cisco Virtual Switching System environment is the current lack of distributed

aggregate policing capabilities across different forwarding engines. That is, if a policer is required to span across

multiple forwarding engines, each forwarding engine keeps track of its own token-bucket quota and hence generally

results in the under-policing of traffic. This situation usually manifests itself when applying policers on the following

types of interfaces (Figure 39):

●

VLAN interfaces that consist of member ports that belong to multiple forwarding engines

●

Port-channel interfaces that consist of member ports that belong to multiple forwarding engines

●

Shared aggregate policers that consist of member ports that belong to multiple forwarding engines

Figure 39. Aggregate Policing Within Cisco Virtual Switching System

Microflow Policing and User-Based Rate Limiting

Microflow policing allows you to police individual traffic flows at a given rate. Depending on the flow mask used

(whether it is a unique source or destination MAC address, source or destination IP address, or TCP/User Datagram

Protocol [UDP] port numbers), you can use microflow policing to limit the amount of data sent or received for that flow

on a port or VLAN basis. In the microflow definition, you can either drop packets that exceed the prescribed rate limit

or have their DSCP value marked down.

User Based Rate Limiting (UBRL) is a form of microflow policing that also supports the policing of individual flows.

The primary difference is that you can specify a source-only flow or destination-only flow rather than the full source or

destination address of the packet.

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Cisco WS-X6708-10G-3CXL= - 10 Gigabit Ethernet Module Manual de usuario Pagina 58