how to deal with RTL and behavior model mismatch

Hi All,

the block i am verifying is a traffic policer using token-bucket algorithm in a network chip.
the algorithm is simple: dut add tokens with a configured period, and also receive incoming packets;
if a packet length is less than or equal to the remained tokens in bucket, then it's outputted with GREEN color;
otherwise, it's outputted with RED color.

the challenge is: since dut take some extra cycles to update tokens each time, while model doesn't need to. so their output colors may be not same. in the interval that model has updated tokens while dut hasn't, many packets may come in. since model and dut may do different decisions, remained tokens no. in them may become more and more different; and more turbulence is added by large delays of multif-flows and simulations become longer. so after a few update periods, the model has been almost useless and untrustable -- more output colors mismatch but TB can't judge if that's just because of RTL timing delays, or real Bug.

i have searched on internet exhaustly but unlucky, haven't found any papers detailing the approaches to deal with this kind of mismatch. so look forward to your great comments. please let me know if i describe clearly.

Great Thanks
Wade