CPU Protection Extensions ETH-CFM
Page 40 7450 ESS System Mangement Guide
CPU Protection Extensions ETH-CFM
CPU protection has been extended to provide the ability to explicitly limit the amount of ETH-
CFM traffic that arrives at the CPU for processing. ETH-CFM packets that are redirected to
the CPU by either a Management Endpoint (MEP) or a Management Intermediate Point (MIP)
will be subject to the configured limit of the associated policy. Up to four CPU protection
policies may include up to ten individual eth-cfm specific entries. The eth-cfm entries allow
the operator to apply a packet per second rate limit to the matching combination of level and
opcode, for eth-cfm packet that are redirected to the CPU. Any eth-cfm traffic that is
redirected to the CPU by a Management Point (MP) that does not match any entries of the
applied policy is still subject to the overall rate limit of the policy itself. Any eth-cfm packets
that are not redirected to the CPU are not subject to this function and are treated as transit data,
subject to the applicable QoS policy.
The operator first creates a CPU Policy and includes the required eth-cfm entries. Overlap is
allowed for the entries within a policy, first match logic is applied. This means ordering the
entries in the proper sequence is important to ensure the proper behavior is achieved. Even
thought the number of eth-cfm entries is limited to ten, the entry numbers have a valid range
from 1-100 to allow for ample space to insert policies between one and other.
Ranges are allowed when configuring the Level and the OpCode. Ranges provide the operator
a simplified method for configuring multiple combinations. When more than one Level or
OpCode is configured in this manner the configured rate limit is applied separately to each
combination of level and OpCode match criteria. For example, if the Levels are configured
with using a range of 5-7 and the OpCode is configured for 3,5 with a rate of 1. That restricts
all possible combinations on that single entry to a rate of 1 packet per second. In this example
six different match conditions are programmed behind the scene.
Once the policy is created it must be applied to a SAP/Binding within a service for these rates
to take affect. This means the rate is on a per SAP/Binding basis. Only a single policy may be
applied to a SAP/Binding. The “eth-cfm-monitoring” option must be configured in order for
the eth-cfm entries to be applied when the policy is applied to the SAP/Binding. If this option
Table 4: Ranges versus Levels and OpCodes
Level OpCode Rate
531
551
631
651
731
751
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