You can set values for pause threshold (x-off), resume threshold (x-on) and headroom for a traffic class on all PFC enabled
ports on a given line card location using the hw-module profile priority-flow-control command.
The existing queue-limit for that traffic class on an egress queuing policy on that line card will have no impact and the
effective queue limit is pause threshold + headroom.
Note
|
For optimal functionality in hardware, for a given traffic class, the resume threshold should not be more than 10% of the
pause threshold and the headroom should be at least 100KB.
|
Note
|
Due to ASIC errors, some packets may get dropped from the burst traffic. In order to resolve this scenario, flow control is
enabled by default on RP to SC link on NCS5500 modular chassis. This will limit the number of packets to be sent on the EPC
link from RP card to SC card. This is a default behavior.
|
For details on how to configure PFC on an interface, see the
Interface and Hardware Component Configuration Guide for Cisco NCS 5500 Series Routers.
Configuration Example
Apart from the line card level PFC parameters configured through the hw-module profile, PFC Receive functionality requires
an egress policy to be applied and egress traffic to be mapped to unique queues per CoS value on all PFC enabled interfaces.
You can accomplish this with the following sequence of configuration.
-
Configure ingress classification policy to map incoming traffic to the right CoS / priority queue.
-
Configure egress queuing policy with the relevant shaping, priority and weighted fair queue scheduling actions
-
Attach the ingress policy on all interfaces where traffic can come in.
-
Attach the egress policy on all PFC enabled interfaces in the system.
-
Configure hw-module priority-flow-control profile and configure pause, resume and headroom for all PFC traffic-classes on
all line card locations requiring PFC feature.
Reload the line card for all traffic-class addition and deletions. Parameters within an already configured traffic-class can
be edited 'in place' without requiring a line card reload.
Hw-module configuration:
===================
RP/0/RP1/CPU0:NCS5504(config)#hw-module profile priority-flow-control location 0/0/CPU0
tRP/0/RP1/CPU0:NCS5504(config-pfc-loc)# traffic-class 3 pause-threshold 403200 bytes resume-threshold 40320 bytes headroom 441600 bytes
RP/0/RP1/CPU0:NCS5504(config-pfc-loc)# traffic-class 4 pause-threshold 403200 bytes resume-threshold 40320 bytes headroom 441600 bytes
RP/0/RP1/CPU0:NCS5504(config-pfc-loc)#
Class-map configuration:
===================
RP/0/RP1/CPU0:NCS5504(config)#class-map match-any MAIN_IN_CMAP_1
match prRP/0/RP1/CPU0:NCS5504(config-cmap)# match precedence 1
RP/0/RP1/CPU0:NCS5504(config-cmap)# end-class-map
RP/0/RP1/CPU0:NCS5504(config)#!
RP/0/RP1/CPU0:NCS5504(config)#class-map match-any MAIN_IN_CMAP_2
RP/0/RP1/CPU0:NCS5504(config-cmap)# match precedence 2
RP/0/RP1/CPU0:NCS5504(config-cmap)# end-class-map
RP/0/RP1/CPU0:NCS5504(config)#!
RP/0/RP1/CPU0:NCS5504(config)#class-map match-any MAIN_IN_CMAP_3
RP/0/RP1/CPU0:NCS5504(config-cmap)# match precedence 3
RP/0/RP1/CPU0:NCS5504(config-cmap)# end-class-map
RP/0/RP1/CPU0:NCS5504(config)#!
RP/0/RP1/CPU0:NCS5504(config)#class-map match-any MAIN_IN_CMAP_4
RP/0/RP1/CPU0:NCS5504(config-cmap)# match precedence 4
RP/0/RP1/CPU0:NCS5504(config-cmap)# end-class-map
RP/0/RP1/CPU0:NCS5504(config)#!
RP/0/RP1/CPU0:NCS5504(config)#class-map match-any MAIN_IN_CMAP_5
RP/0/RP1/CPU0:NCS5504(config-cmap)# match precedence 5
RP/0/RP1/CPU0:NCS5504(config-cmap)# end-class-map
RP/0/RP1/CPU0:NCS5504(config)#!
RP/0/RP1/CPU0:NCS5504(config)#class-map match-any MAIN_IN_CMAP_6
RP/0/RP1/CPU0:NCS5504(config-cmap)# match precedence 6
RP/0/RP1/CPU0:NCS5504(config-cmap)# end-class-map
RP/0/RP1/CPU0:NCS5504(config)#!
RP/0/RP1/CPU0:NCS5504(config)#class-map match-any MAIN_IN_CMAP_7
RP/0/RP1/CPU0:NCS5504(config-cmap)# match precedence 7
RP/0/RP1/CPU0:NCS5504(config-cmap)# end-class-map
RP/0/RP1/CPU0:NCS5504(config)#!
RP/0/RP1/CPU0:NCS5504(config)#class-map match-any PFC_OUT_CMAP_1
RP/0/RP1/CPU0:NCS5504(config-cmap)# match traffic-class 1
RP/0/RP1/CPU0:NCS5504(config-cmap)# end-class-map
RP/0/RP1/CPU0:NCS5504(config)#!
RP/0/RP1/CPU0:NCS5504(config)#class-map match-any PFC_OUT_CMAP_2
RP/0/RP1/CPU0:NCS5504(config-cmap)# match traffic-class 2
RP/0/RP1/CPU0:NCS5504(config-cmap)# end-class-map
RP/0/RP1/CPU0:NCS5504(config)#!
RP/0/RP1/CPU0:NCS5504(config)#class-map match-any PFC_OUT_CMAP_3
RP/0/RP1/CPU0:NCS5504(config-cmap)# match traffic-class 3
RP/0/RP1/CPU0:NCS5504(config-cmap)# end-class-map
RP/0/RP1/CPU0:NCS5504(config)#!
RP/0/RP1/CPU0:NCS5504(config)#class-map match-any PFC_OUT_CMAP_4
RP/0/RP1/CPU0:NCS5504(config-cmap)# match traffic-class 4
RP/0/RP1/CPU0:NCS5504(config-cmap)# end-class-map
RP/0/RP1/CPU0:NCS5504(config)#!
RP/0/RP1/CPU0:NCS5504(config)#class-map match-any PFC_OUT_CMAP_5
RP/0/RP1/CPU0:NCS5504(config-cmap)# match traffic-class 5
RP/0/RP1/CPU0:NCS5504(config-cmap)# end-class-map
RP/0/RP1/CPU0:NCS5504(config)#!
RP/0/RP1/CPU0:NCS5504(config)#class-map match-any PFC_OUT_CMAP_6
RP/0/RP1/CPU0:NCS5504(config-cmap)# match traffic-class 6
RP/0/RP1/CPU0:NCS5504(config-cmap)# end-class-map
RP/0/RP1/CPU0:NCS5504(config)#!
RP/0/RP1/CPU0:NCS5504(config)#class-map match-any PFC_OUT_CMAP_7
RP/0/RP1/CPU0:NCS5504(config-cmap)# match traffic-class 7
RP/0/RP1/CPU0:NCS5504(config-cmap)# end-class-map
RP/0/RP1/CPU0:NCS5504(config)#!
RP/0/RP1/CPU0:NCS5504(config)#
Ingress Policy-map configuration:
=========================
RP/0/RP1/CPU0:NCS5504(config)#policy-map MAIN_OUT_TC_SUPPORTING_UUT
RP/0/RP1/CPU0:NCS5504(config-pmap)# class MAIN_IN_CMAP_1
RP/0/RP1/CPU0:NCS5504(config-pmap-c)# set traffic-class 1
RP/0/RP1/CPU0:NCS5504(config-pmap-c)# !
RP/0/RP1/CPU0:NCS5504(config-pmap-c)# class MAIN_IN_CMAP_2
RP/0/RP1/CPU0:NCS5504(config-pmap-c)# set traffic-class 2
RP/0/RP1/CPU0:NCS5504(config-pmap-c)# !
RP/0/RP1/CPU0:NCS5504(config-pmap-c)# class MAIN_IN_CMAP_3
RP/0/RP1/CPU0:NCS5504(config-pmap-c)# set traffic-class 3
RP/0/RP1/CPU0:NCS5504(config-pmap-c)# !
RP/0/RP1/CPU0:NCS5504(config-pmap-c)# class MAIN_IN_CMAP_4
RP/0/RP1/CPU0:NCS5504(config-pmap-c)# set traffic-class 4
RP/0/RP1/CPU0:NCS5504(config-pmap-c)# !
RP/0/RP1/CPU0:NCS5504(config-pmap-c)# class MAIN_IN_CMAP_5
RP/0/RP1/CPU0:NCS5504(config-pmap-c)# set traffic-class 5
RP/0/RP1/CPU0:NCS5504(config-pmap-c)# !
RP/0/RP1/CPU0:NCS5504(config-pmap-c)# class MAIN_IN_CMAP_6
RP/0/RP1/CPU0:NCS5504(config-pmap-c)# set traffic-class 6
RP/0/RP1/CPU0:NCS5504(config-pmap-c)# !
RP/0/RP1/CPU0:NCS5504(config-pmap-c)# class MAIN_IN_CMAP_7
RP/0/RP1/CPU0:NCS5504(config-pmap-c)# set traffic-class 7
RP/0/RP1/CPU0:NCS5504(config-pmap-c)# !
RP/0/RP1/CPU0:NCS5504(config-pmap-c)#
RP/0/RP1/CPU0:NCS5504(config-pmap-c)#
Egress policy-map configuration:
============================
RP/0/RP1/CPU0:NCS5504(config)#policy-map PFC_UUT_bwrr_microsoft
asRP/0/RP1/CPU0:NCS5504(config-pmap)# class PFC_OUT_CMAP_1
RP/0/RP1/CPU0:NCS5504(config-pmap-c)# bandwidth remaining ratio 5
RP/0/RP1/CPU0:NCS5504(config-pmap-c)# queue-limit 192 us
RP/0/RP1/CPU0:NCS5504(config-pmap-c)# !
RP/0/RP1/CPU0:NCS5504(config-pmap-c)# class PFC_OUT_CMAP_2
RP/0/RP1/CPU0:NCS5504(config-pmap-c)# bandwidth remaining ratio 5
RP/0/RP1/CPU0:NCS5504(config-pmap-c)# queue-limit 192 us
RP/0/RP1/CPU0:NCS5504(config-pmap-c)# !
RP/0/RP1/CPU0:NCS5504(config-pmap-c)# class PFC_OUT_CMAP_3
RP/0/RP1/CPU0:NCS5504(config-pmap-c)# bandwidth remaining ratio 20
RP/0/RP1/CPU0:NCS5504(config-pmap-c)# random-detect ecn
RP/0/RP1/CPU0:NCS5504(config-pmap-c)# random-detect 224 kbytes 275 kbytes
RP/0/RP1/CPU0:NCS5504(config-pmap-c)# !
RP/0/RP1/CPU0:NCS5504(config-pmap-c)# class PFC_OUT_CMAP_4
RP/0/RP1/CPU0:NCS5504(config-pmap-c)# bandwidth remaining ratio 20
RP/0/RP1/CPU0:NCS5504(config-pmap-c)# random-detect ecn
RP/0/RP1/CPU0:NCS5504(config-pmap-c)# random-detect 224 kbytes 275 kbytes
RP/0/RP1/CPU0:NCS5504(config-pmap-c)# !
RP/0/RP1/CPU0:NCS5504(config-pmap-c)# class PFC_OUT_CMAP_5
RP/0/RP1/CPU0:NCS5504(config-pmap-c)# bandwidth remaining ratio 20
RP/0/RP1/CPU0:NCS5504(config-pmap-c)# queue-limit 192 us
RP/0/RP1/CPU0:NCS5504(config-pmap-c)# !
RP/0/RP1/CPU0:NCS5504(config-pmap-c)# class PFC_OUT_CMAP_6
RP/0/RP1/CPU0:NCS5504(config-pmap-c)# bandwidth remaining ratio 1
RP/0/RP1/CPU0:NCS5504(config-pmap-c)# queue-limit 192 us
RP/0/RP1/CPU0:NCS5504(config-pmap-c)# !
RP/0/RP1/CPU0:NCS5504(config-pmap-c)# class PFC_OUT_CMAP_7
RP/0/RP1/CPU0:NCS5504(config-pmap-c)# shape average percent 10
RP/0/RP1/CPU0:NCS5504(config-pmap-c)# priority level 1
RP/0/RP1/CPU0:NCS5504(config-pmap-c)# queue-limit 192 us
RP/0/RP1/CPU0:NCS5504(config-pmap-c)# !
RP/0/RP1/CPU0:NCS5504(config-pmap-c)# class class-default
RP/0/RP1/CPU0:NCS5504(config-pmap-c)# bandwidth remaining ratio 20
RP/0/RP1/CPU0:NCS5504(config-pmap-c)# queue-limit 192 us
RP/0/RP1/CPU0:NCS5504(config-pmap-c)# !
Applying policy to ingress and egress interface:
========================================
RP/0/RP1/CPU0:NCS5504#show running-config interface hundredGigE 0/0/0/0
interface HundredGigE0/0/0/0
service-policy input MAIN_OUT_TC_SUPPORTING_UUT
ipv4 address 100.1.9.1 255.255.255.0
ipv6 address 100:1:9::1/96
priority-flow-control mode on
interface HundredGigE0/1/0/19
service-policy output PFC_ECN_UUT_bwrr_microsoft
ipv4 address 10.1.9.1 255.255.255.0
ipv6 address 10:1:9::1/96
priority-flow-control mode on
!
Running Configuration
RP/0/RP1/CPU0:NCS5504# show running-config hw-module profile priority-flow-control location 0/0/CPU0
Tue Oct 13 10:31:58.035 UTC
hw-module profile priority-flow-control location 0/0/CPU0
traffic-class 3 pause-threshold 403200 bytes resume-threshold 40320 bytes headroom 441600 bytes
traffic-class 4 pause-threshold 403200 bytes resume-threshold 40320 bytes headroom 441600 bytes
!
RP/0/RP1/CPU0:NCS5504#show running-config class-map
Tue Oct 13 10:32:02.400 UTC
class-map match-any MAIN_IN_CMAP_1
match precedence 1
end-class-map
!
class-map match-any MAIN_IN_CMAP_2
match precedence 2
end-class-map
!
class-map match-any MAIN_IN_CMAP_3
match precedence 3
end-class-map
!
class-map match-any MAIN_IN_CMAP_4
match precedence 4
end-class-map
!
class-map match-any MAIN_IN_CMAP_5
match precedence 5
end-class-map
!
class-map match-any MAIN_IN_CMAP_6
match precedence 6
end-class-map
!
class-map match-any MAIN_IN_CMAP_7
match precedence 7
end-class-map
!
class-map match-any PFC_OUT_CMAP_1
match traffic-class 1
end-class-map
!
class-map match-any PFC_OUT_CMAP_2
match traffic-class 2
end-class-map
!
class-map match-any PFC_OUT_CMAP_3
match traffic-class 3
end-class-map
!
class-map match-any PFC_OUT_CMAP_4
match traffic-class 4
end-class-map
!
class-map match-any PFC_OUT_CMAP_5
match traffic-class 5
end-class-map
!
class-map match-any PFC_OUT_CMAP_6
match traffic-class 6
end-class-map
!
class-map match-any PFC_OUT_CMAP_7
match traffic-class 7
end-class-map
!
RP/0/RP1/CPU0:NCS5504#show running-config policy-map PFC_UUT_bwrr_microsoft
Tue Oct 13 10:32:18.009 UTC
policy-map PFC_UUT_bwrr_microsoft
class PFC_OUT_CMAP_1
bandwidth remaining ratio 5
queue-limit 192 us
!
class PFC_OUT_CMAP_2
bandwidth remaining ratio 5
queue-limit 192 us
!
class PFC_OUT_CMAP_3
bandwidth remaining ratio 20
random-detect ecn
random-detect 224 kbytes 275 kbytes
!
class PFC_OUT_CMAP_4
bandwidth remaining ratio 20
random-detect ecn
random-detect 224 kbytes 275 kbytes
!
class PFC_OUT_CMAP_5
bandwidth remaining ratio 20
queue-limit 192 us
!
class PFC_OUT_CMAP_6
bandwidth remaining ratio 1
queue-limit 192 us
!
class PFC_OUT_CMAP_7
shape average percent 10
priority level 1
queue-limit 192 us
!
class class-default
bandwidth remaining ratio 20
queue-limit 192 us
!
end-policy-map
!
RP/0/RP1/CPU0:NCS5504#show running-config policy-map MAIN_OUT_TC_SUPPORTING_UUT
Tue Oct 13 10:32:31.430 UTC
policy-map MAIN_OUT_TC_SUPPORTING_UUT
class MAIN_IN_CMAP_1
set traffic-class 1
!
class MAIN_IN_CMAP_2
set traffic-class 2
!
class MAIN_IN_CMAP_3
set traffic-class 3
!
class MAIN_IN_CMAP_4
set traffic-class 4
!
class MAIN_IN_CMAP_5
set traffic-class 5
!
class MAIN_IN_CMAP_6
set traffic-class 6
!
class MAIN_IN_CMAP_7
set traffic-class 7
!
class class-default
!
end-policy-map
!
Verification
Incoming PFC frames are displayed on the PFC Rx statistics that are shown in the command below. If the interface is enabled
for PFC and has an egress queuing policy applied to it, then the queue corresponding to the incoming CoS value on the PFC
frames is paused
When PFC pause thresholds are crossed, PFC Tx frames are sent out of the PFC enabled interfaces sourcing such traffic on that
network processing core. This can be verified against the PFC Tx statistics that are shown on this command. After the congestion
condition ceases and the buffer resource usage goes below the PFC resume thresholds, a PFC resume frame is sent and the PFC
Tx frames are stopped.
RP/0/RP1/CPU0:NCS5504#show controllers hundredGigE 0/0/0/0 priority-flow-control statistics
Mon Oct 12 12:22:39.362 UTC
Priority flow control information for interface HundredGigE0/0/0/0:
Priority Flow Control:
Total Rx PFC Frames: 0
Total Tx PFC Frames: 1764273
Rx Data Frames Dropped: 0
CoS Status Rx Frames Tx Frames
--- ------ ---------- ----------
0 off 0 0
1 off 0 0
2 off 0 0
3 on 0 882032
4 on 0 882241
5 off 0 0
6 off 0 0
7 off 0 0
The status of the traffic-class and the configured parameters under it on the hw-module priority-flow-control profile can
be checked using the following command.RP/0/RP1/CPU0:NCS5504#show controllers npu priority-flow-control loc 0/0/CPU0
Mon Oct 12 14:35:17.531 UTC
Location: 0/0/CPU0
PFC: Enabled
TC Pause-threshold Resume-Threshold Headroom
-------------------------------------------------------
3 403200 bytes 40320 bytes 441600 bytes
4 403200 bytes 40320 bytes 441600 bytes