Priority Mapping on SONET/SDH OC48/STM16 IQE PICs

The SONET/SDH OC48/STM16 IQE PIC supports three priorities for traffic below the guaranteed rate and two priorities for traffic above the guaranteed rate. The mapping between Junos OS priorities and the SONET/SDH OC48/STM16 IQE PIC hardware priorities below and above the guaranteed rate (CIR) is shown in Table 1. By default, a strict-high queue gets the excess high priority and all other queues get the excess low priority.

Table 1: Junos OS Priorities Mapped to SONET/SDH OC48/STM16 IQE PIC Hardware Priorities
Junos OS Priority	SONET/SDH OC48/STM16 IQE PIC Hardware Priority Below Guaranteed Rate For Logical Interfaces	SONET/SDH OC48/STM16 IQE PIC Hardware Priority Above Guaranteed Rate For Logical Interfaces (Excess Priority)
Strict-high	High	High
High	High	Low
Medium-high	Medium	Low
Medium-low	Medium	Low
Low	Low	Low

The SONET/SDH OC48/STM16 IQE PIC internally maps the excess priority and the excess rate to achieve configuration parity with the other IQE PICs.

The queue-level mapping for the excess priority and the excess rate is shown in Table 2.

Table 2: Queue-Level Mapping for Excess Priority and Excess Rate
Configured Values				Mapped Values
Transmit Priority	Transmit Rate %	Excess Rate %	Excess Priority	Transmit Priority	Transmit Rate %	Excess Rate %	Excess Priority
Strict-high	X	Any value	Any value	No mapping	No mapping	Ignored	Ignored
Strict-high	0	Any value	Any value	No mapping	No mapping	Ignored	Ignored
High or Medium or Low	X	Any value	Any value	No mapping	No mapping	Ignored	Ignored
	0	X	High	Medium	X	Ignored	Low
		X	Low	Low	X	Ignored	Low
		0	Any value	No mapping	No mapping	Ignored	Ignored

Note:

The value X is the configured rate.

The SONET/SDH OC48 IQE PIC maps the excess rate and the excess priority based on the following conditions:

If the transmit priority is not strict-high, the transmit rate is zero, the excess rate is nonzero, and the excess priority is high, then the value of the transmit priority is changed to medium and the value of the excess priority is changed to low.
If the transmit priority is not strict-high, the transmit rate is zero, the excess rate is nonzero, and the excess priority is low, then the value of the transmit priority is changed to low and the value of the excess priority is changed to low.
In all the cases other than those mentioned above, the SONET/SDH OC48 IQE PIC ignores the excess rate and the excess priority configurations and generates the system log messages.

Priority Mapping on SONET/SDH OC48/STM16 IQE PICs

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