Validate that device ignores PFC frame received with no bit set in the class enable vector

[neethajohn]

Description We need to cover 2 cases here

1. pfc frame accounting on the DUT
2. DUT reaction to the pfc frames

Device should ignore PFC frame received with no bit set in the class enable vector field. It should not account for those and not react to pfc frames

With the following topology,

ixia port 1 --> dut --> ixia port2

1. Send lossless and lossy traffic from ixia port 1 to ixia port 2
2. Send pfc frames with class enable vector field set to 0 and max pause quanta specified in all time class fields from ixia port2 at a duration needed to fully block the egress queue

Describe the results you expected:

1. "show pfc counters" on the dut should not account those packets in RX pfc
2. With traffic running and pause frames being sent, "show queue counters" should show a continuous increase in traffic