Edge-Core ECS4660-28F, Руководство по управлению, Страница: 1419 / 2020

C
HAPTER
42
| Quality of Service Commands
– 1419 –
When a packet of size B bytes arrives at time t, the following happens if
trTCM is configured to operate in color-blind mode:
■
If Tp(t)-B < 0, the packet is red, else
■
if Tc(t)-B < 0, the packet is yellow and Tp is decremented by B, else
■
the packet is green and both Tp and Tc are decremented by B.
When a packet of size B bytes arrives at time t, the following happens if
trTCM is configured to operate in color-aware mode:
■
If the packet has been precolored as red or if Tp(t)-B < 0, the
packet is red, else
■
if the packet has been precolored as yellow or if Tc(t)-B < 0, the
packet is yellow and Tp is decremented by B, else
■
the packet is green and both Tp and Tc are decremented by B.
◆ The trTCM can be used to mark a IP packet stream in a service, where
different, decreasing levels of assurances (either absolute or relative)
are given to packets which are green, yellow, or red. Refer to RFC 2698
for more information on other aspects of trTCM.
E
XAMPLE
This example creates a policy called “rd-policy,” uses the class command to
specify the previously defined “rd-class,” uses the set phb command to
classify the service that incoming packets will receive, and then uses the
police trtcm-color-blind command to limit the average bandwidth to
100,000 Kbps, the committed burst rate to 4000 bytes, the peak
information rate to 1,000,000 kbps, the peak burst size to 6000, to remark
any packets exceeding the committed burst size, and to drop any packets
exceeding the peak information rate.
Console(config)#policy-map rd-policy
Console(config-pmap)#class rd-class
Console(config-pmap-c)#set phb 3
Console(config-pmap-c)#police trtcm-color-blind 100000 4000 100000 6000
conform-action transmit exceed-action 0 violate-action drop
Console(config-pmap-c)#
set cos
This command modifies the class of service (CoS) value for a matching
packet (as specified by the match command) in the packet’s VLAN tag. Use
the no form to remove this setting.
S
YNTAX
[ no ] set cos cos-value
cos-value - Class of Service value. (Range: 0-7)
D
EFAULT
S
ETTING
None
C
OMMAND
M
ODE
Policy Map Class Configuration