問題文
A three-color marking policer is going in at the edge of a campus. The switches upstream of it have already set a loss priority on part of the traffic, and the team asks whether the meter of the new policer will take notice of that. Which statement describes what they have to settle?
選択肢
- One mode of the meter treats the stream as uncolored and does not read any loss priority already set, while the other one inspects the loss priority field that an upstream device or a classifier has written.
- Whether the meter reads the earlier value follows from the burst sizes, because a policer written with an excess burst size reads it and one written with a peak rate does not.
- The meter never reads a loss priority that arrives on the packet, so the team has no choice to make here and has to place a classifier ahead of the policer if the earlier value matters.
- The meter always reads the loss priority the packet arrives with, so the only decision left in front of the team is whether the marker of the new policer is to be allowed to lower that value as well as to raise it, independently of what the meter found.