shaping and policing 针对网络拥塞所做的策略做到限速，工作的Q之前
shaping 是对超出的速率的包进行缓存，等速率降下来在发出去
只能应用在出方向，能减少TCP的重传不能making
policing是对超出的速率的包drop或者making，在出入方向都可以。
理解令牌桶的原理（token bucket）：
BC=8000bite 速率限制在64kbs 我们求下TC=8/128=0.0625S
一半的时间就把令牌桶沾满了，下个0.625s就没有令牌了，如果是shaping缓存，policing直接drop，从1s时间来看就有半秒时间空闲，达到限速目的。
两个令牌桶BC=BE的情况下
在125毫秒的时间把BC BE都占满了，到下一个65.5毫秒又把BC占满了BE还没有空闲就drop掉剩下的流量
CIR （committed information rate）承诺信息速率 bps
Tc （ time committed）承诺时间 125毫秒 1/8秒
Bc （brust committed）承诺的突发量 bite
Be （burst excess ） 超出的突发量
CIR=BC/Tc 在配置的时候我们只关心CIR就行了
shaping：GTS（generic traffic shaping）
frame relay traffic shaping
class-based shaping
policing ：committed access rate （CAR）
class-dased policing
GTS:可以用在任何接口
Router(config)#int s1/0
Router(config-if)#tra
Router(config-if)#traffi
Router(config-if)#traffic-shape ?
group configure token bucket: group <access-list> CIR (bps) [Bc (bits) [Be
(bits)]]
rate configure token bucket: CIR (bps) [Bc (bits) [Be (bits)]]
Router(config-if)#traffic-shape ra
Router(config-if)#traffic-shape rate ?
<8000-100000000> Target Bit Rate (bits per second)
Router(config-if)#traffic-shape rate 64000 ?
<0-100000000> bits per interval, sustained
<cr>
Router(config-if)#traffic-shape rate 64000 8000 ?
<0-100000000> bits per interval, excess in first interval
<cr>
Router(config-if)#traffic-shape rate 64000 8000 8000 1000
Router#show traffic-shape
Interface Se1/0
Access Target Byte Sustain Excess Interval Increment Adapt
VC List Rate Limit bits/int bits/int (ms) (bytes) Active
- 64000 2000 8000 8000 125 1000 -
CIR (BC+BE)/8 BC BE TC BC(8000bite/8划算成bytes)
还可以针对特定ACL来限速，但traffic-rate和traffic rate group不能同时运用在一个接口上
Router(config)#access-list 110 permit ip host 202.1.100.100 host 191.1.1.1
Router(config-if)#traffic-shape group 110 128000 8000 8000 1000
CBSHAPING就是结合MQC来做加上条命令而已
R1(config)#policy-map cbshap
R1(config-pmap)#cl
R1(config-pmap)#class TEL
R1(config-pmap-c)#sha
R1(config-pmap-c)#shape ?
adaptive Enable Traffic Shaping adaptation to BECN
average configure token bucket: CIR (bps) [Bc (bits) [Be (bits)]],
send out Bc only per interval
fecn-adapt Enable Traffic Shaping reflection of FECN as BECN
fr-voice-adapt Enable rate adjustment depending on voice presence
max-buffers Set Maximum Buffer Limit
peak configure token bucket: CIR (bps) [Bc (bits) [Be (bits)]],
send out Bc+Be per interval
R1(config-pmap-c)#shape av
R1(config-pmap-c)#shape average ?
<8000-154400000> Target Bit Rate (bits per second), the value needs to be
multiple of 8000
percent % of interface bandwidth for Committed information rate
R1(config-pmap-c)#shape average 64000
R1(config-pmap-c)#shape max-buffers 200
CAR:
R1(config-if)#rate-limit output ?
<8000-2000000000> Bits per second
access-group Match access list
dscp Match dscp value
qos-group Match qos-group ID
R1(config-if)#rate-limit output 256000 ?
<1000-512000000> Normal burst bytes
R1(config-if)#rate-limit output 256000 2000 2000 ?
conform-action action when rate not exceeded
R1(config-if)#rate-limit output 256000 2000 2000 con
R1(config-if)#rate-limit output 256000 2000 2000 conform-action ?
continue scan other rate limits
drop drop packet
set-dscp-continue set dscp, scan other rate limits
set-dscp-transmit set dscp and send it
set-mpls-exp-imposition-continue set exp during imposition, scan other rate
limits
set-mpls-exp-imposition-transmit set exp during imposition and send it
set-prec-continue rewrite packet precedence, scan other rate
limits
set-prec-transmit rewrite packet precedence and send it
set-qos-continue set qos-group, scan other rate limits
set-qos-transmit set qos-group and send it
transmit transmit packet
shaping以bite为单位 policing以bity为单位
R1#show run int s1/0
Building configuration...
Current configuration : 207 bytes
!
interface Serial1/0
no ip address
rate-limit output 256000 2000 2000 conform-action transmit exceed-action drop
CIR BC BE
扩展：
access-list 101 permit tcp any any eq www
rate-limit output access-group 120 64000 5000 5000 conform-action transmit exceed-action drop
rate-limit output 128000 2000 2000 conform-action continue exceed-action drop大范围
continue命令是如果第一条匹配还可以往下查
class-dased policing
拿到第一个桶令牌的是conforms
拿到第二个桶令牌的是exceed
拿不到的violate
policy-map liang
class TEL
police cir 64000
conform-action transmit
exceed-action transmit
violate-action drop
本文转自q狼的诱惑 51CTO博客，原文链接：http://blog.51cto.com/liangrui/552058，如需转载请自行联系原作者
