Huawei Quidway S3900 Series Operation Manual page 668

Operation Manual - QoS&QoS Profile
Quidway S3900 Series Ethernet Switches-Release 1510
I. Traffic evaluation and the token bucket
The token bucket can be considered as a container with a certain capacity to hold
tokens. The system puts tokens into the bucket at the set rate. When the token bucket
is full, the extra tokens will overflow and the number of tokens in the bucket stops
increasing.
Packet to be sent on this interface Packet to be sent on this interface Packet sent via this interface Packet to be sent on this interface Packet to be sent on this interface Packet to be sent on this interface Packet sent via this interface
需由此接口发送的包 需由此接口发送的包 需由此接口发送的包 需由此接口发送的包 需由此接口发送的包 需由此接口发送的包 需由此接口发送的包
Figure 1-4 Evaluate the traffic with the token bucket
1) Evaluate the traffic with the token bucket
The evaluation for the traffic specification is based on whether the number of tokens in
the bucket can meet the need of packet forwarding. If the number of tokens in the
bucket is enough to forward the packets (generally, one token is associated with a 1-bit
forwarding authority), the traffic is conforming to the specification, and otherwise the
traffic is nonconforming or excess.
When the token bucket evaluates the traffic, its parameter configurations include:
Average rate: The rate at which tokens are put into the bucket, namely, the
permitted average rate of the traffic. It is generally set to committed information
rate (CIR).
Burst size: The capacity of the token bucket, namely, the maximum traffic size that
is permitted in every burst. It is generally set to committed burst size (CBS). The
set burst size must be bigger than the maximum packet length.
One evaluation is performed on each arriving packet. In each evaluation, if the number
of tokens in the bucket is enough, the traffic is conforming to the specification and you
must take away some tokens whose number is corresponding to the packet forwarding
authority; if the number of tokens in the bucket is not enough, it means that too many
tokens have been used and the traffic is excess.
2) Complicated evaluation
You can set two token buckets in order to evaluate more complicated conditions and
implement more flexible regulation policies. For example, TP includes 4 parameters:
Put tokens into the bucket at the set rate Put tokens into the bucket at the set rate Put tokens into the bucket at the set rate Put tokens into the bucket at the set rate
按规定的速率向桶内放置令牌 按规定的速率向桶内放置令牌 按规定的速率向桶内放置令牌 按规定的速率向桶内放置令牌 按规定的速率向桶内放置令牌 按规定的速率向桶内放置令牌 按规定的速率向桶内放置令牌
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Huawei Technologies Proprietary
1-6
Chapter 1 QoS Configuration
Continue to send Continue to send Continue to send Continue to send Continue to send Continue to send Continue to send
继续发送 继续发送 继续发送 继续发送 继续发送 继续发送 继续发送
Token bucket Token bucket Token bucket Token bucket
令牌桶 令牌桶 令牌桶 令牌桶 令牌桶 令牌桶 令牌桶
Drop Drop Drop Drop
丢弃 丢弃 丢弃 丢弃 丢弃 丢弃 丢弃