Alcatel-Lucent 1643 AMS Applications And Planning Manual page 232

Ethernet Overview
Rate control is supported for every ingress flow on every customer-role port. There is
one rate controller per flow. A "color unaware one-rate two-color marker" is supported,
which can be seen as a degenerate case of the two-rate three-color marker. "Color
unaware" means that the rate controller ignores and overwrites any dropping
precedence given by an upstream network element (network-role ports with
DiffServEdge function (E-NNI) only).
The rate controller is accurate within 5% of the rates specified for the CIR and PIR.
The rate metering comprises the whole Ethernet MAC frame. Products may deviate
from this and count only the IP package size. The rate controller measurement
accuracy is optimized for long frame traffic. Shorter frames are underestimated. Thus,
it is recommended to dimension the transporting network to have always a headroom
of at least 10% bandwidth compared to the committed information rate (CIR)
provisioned.
A two-rate three-color marker is defined by three colors, specifying the dropping
precedence, and two rates as delimiter between the colors. The marker will mark each
packet with a certain color, depending on the rate of arriving packets, and the amount
of credits in the token bucket. The size of the token bucket will determine how long
and far a data burst may be surpassed before the packets are marked with a higher
dropping precedence.
The three colors indicate:
• Green: Low dropping precedence.
• Yellow: Higher dropping precedence.
• Red: The packet will be dropped.
The two rates mean:
Committed Information Rate
(CIR)
....................................................................................................................................................................................................................................
11-56
The committed information rate is the delimiter between green and
yellow packets.
If the information rate is less than the committed information rate,
all frames will be admitted to the egress queues. These frames will
be marked "green", and have a low probability to be dropped at the
egress queues.
Alcatel-Lucent - Proprietary
See notice on first page
Classification, queueing and scheduling
365-312-801R7.2
Issue 3, May 2007