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Cisco Bug: CSCvt97619 - Mixed speed L1 port creation failures on front ports connected to PM-1 on NC57 card

Last Modified

Oct 09, 2020

Products (1)

  • Cisco ASR 9000 Series Aggregation Services Routers

Known Affected Releases

7.2.1.BASE 7.3.1.BASE

Description (partial)

L1 Port creation fails when 40g and 100g SFPs are plugged into certain combination of front ports.

After discussing with broadcom, it is confirmed that PM (Port Macro)#1 on NC57 has hardware limitation where  usage of 2 PLLs (in NIF PM #1) which requires two VCO/PLL is not allowed. 
This means that all the serdes lanes(8 lanes)  in PM#1 can operate at single speed and can't operate at different speeds. 
This limitation applies to NC57-SE, but not on NC55 as in NC55 all the lanes of PM#1 are connected to a single front port.

So front ports 0,1 and similarly front ports 14,15 can operate on below modes
   - both at 40g speed
   - both at 100g speed 
   - one in 40g and other at 4x10g
   - one in 100g and other at 4x25g
If we enable these 2 ports under different port speed we likely to hit interface down, flap or other errors.
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