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The Per-Flow Admission feature provides explicit controls to limit packet flow into a WAN edge in order to protect already admitted flows on the routing/WAN edge.
Your software release may not support all the features documented in this module. For the latest caveats and feature information, see Bug Search Tool and the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the feature information table.
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A class must have bandwidth or priority defined before configuring the Per-Flow Admission feature.
Per-flow admission is currently supported only on Ethernet and serial interfaces, and Dynamic Multipoint Virtual Private Network (DMVPN) tunnels.
Information About Per-Flow Admission
Application (mainly voice and video) quality drops when they are connected from a branch to head quarters and data centers over a WAN because the WAN interface bandwidth is limited and always comes at a premium cost. There are no well-defined controls to restrict flows through a WAN link and no explicit controls to limit the flows to protect already admitted flows. This limitation leads to quality degradation of already admitted flows.
The Per-Flow Admission feature allows operators to understand the number of flows that can be accommodated into an interface without quality degradation. In most deployments, the N+1st flow affects the quality of all existing valid first N flows. The Per-Flow Admission feature enables nodes to automatically learn about flows and their bandwidth as they get accommodated into the interface where bandwidth is at a premium. The network node accommodates only flows that the interface can handle, and it drops flows thereafter.
The following are benefits of integrating the Per-Flow Admission feature to Quality of Service (QoS):
How to Configure Per-Flow Admission
1.
enable
2.
configure
terminal
3.
metadata
flow
4.
class-map [match-all
|
match-any]
class-map-name
5.
match
metadata cac status {admitted |
un-admitted}
6.
exit
7.
class-map [match-all
|
match-any]
class-map-name
8.
match
dscp
dscp-value
9.
end
1.
enable
2.
configure
terminal
3.
policy-map
policy-map-name
4.
class {class-name
|
class-default}
5.
set
dscp
dscp-value
6.
class {class-name
|
class-default}
7.
set
dscp
dscp-value
8.
end
A class must have bandwidth or priority defined before configuring per-flow admission.
1.
enable
2.
configure
terminal
3.
policy-map
policy-map-name
4.
class {class-name
|
class-default}
5.
bandwidth {kilobits
|
percent
percentage}
6.
admit
cac
local
7. rate {kbps | percent percentage}
8.
flow rate fixed
kbps
flow-bit-rate
9.
flow idle-timeout
timeout-value
10.
end
1.
enable
2.
configure
terminal
3.
policy-map
policy-map-name
4.
class {class-name
|
class-default}
5.
service-policy
policy-map
6.
end
7.
configure
terminal
8.
interface
type
number
9.
bandwidth
kilobits
10.
ip
address
ip-address
mask
11.
load-interval
seconds
12.
service-policy
output
policy-map-name
13.
no
shutdown
14.
end
Command or Action | Purpose | |
---|---|---|
Step 1 | enable
Example: Device> enable |
Enables privileged EXEC mode. |
Step 2 |
configure
terminal
Example: Device# configure terminal |
Enters global configuration mode. |
Step 3 |
policy-map
policy-map-name
Example: Device(config)# policy-map test |
Creates a policy map using the specified name and enters policy-map configuration mode. |
Step 4 |
class {class-name
|
class-default}
Example: Device(config-pmap)# class af4 |
Specifies the name of the class whose policy you want to create and enters policy-map class configuration mode. |
Step 5 | service-policy
policy-map
Example: Device(config-pmap-c)# service-policy child | Attaches the policy map to a class. |
Step 6 |
end
Example: Device(config-pmap-c)# end |
Exits policy-map class configuration mode and returns to privileged EXEC mode. |
Step 7 |
configure
terminal
Example: Device# configure terminal |
Enters global configuration mode. |
Step 8 |
interface
type
number
Example: Device(config)# interface Serial2/0 |
Configures the specified interface and enters interface configuration mode. |
Step 9 |
bandwidth
kilobits
Example: Device(config-if)# bandwidth 384 |
Sets a bandwidth value for the interface. |
Step 10 |
ip
address
ip-address
mask
Example: Device(config-if)# ip address 10.10.100.1 255.255.255.0 |
Sets an IP address for an interface. |
Step 11 |
load-interval
seconds
Example: Device(config-if)# load-interval 30 |
Specifies the interval for load calculation of an interface. |
Step 12 |
service-policy
output
policy-map-name
Example: Device(config-if)# service-policy output test |
Attaches a policy map to an interface. |
Step 13 |
no
shutdown
Example: Device(config-if)# no shutdown |
Enables the interface. |
Step 14 | end
Example: Device(config-if)# end |
Exits interface configuration mode and returns to privileged EXEC mode. |
1.
enable
2.
show
policy-map
interface
interface-name
Command or Action | Purpose |
---|
Configuration Examples for Per-Flow Admission
Device> enable Device# configure terminal Device(config)# metadata flow Device(config)# class-map match-all admitted Device(config-cmap)# match metadata cac status admitted Device(config-cmap)# class-map match-all af4 Device(config-cmap)# match dscp af41 af42 af43 Device(config-cmap)# end
Device> enable Device# configure terminal Device(config)# policy-map child Device(config-pmap)# class admitted Device(config-pmap-c)# set dscp af41 Device(config-pmap-c)# class class-default Device(config-pmap-c)# set dscp af42 Device(config-pmap-c)# end
Device> enable Device# configure terminal Device(config)# policy-map test Device(config-pmap)# class af4 Device(config-pmap-c)# bandwidth 200 Device(config-pmap-c)# admit cac local Device(config-pmap-admit-cac)# rate percent 80 Device(config-pmap-admit-cac)# flow rate fixed 100 Device(config-pmap-admit-cac)# flow idle-timeout 50Device(config-pmap-c)# exit
Device> enable Device# configure terminal Device(config-pmap-c)# service-policy child Device(config-pmap-c)# end Device# configure terminal Device(config)# interface Serial2/0 Device(config-if)# bandwidth 384 Device(config-if)# ip address 10.10.100.1 255.255.255.0 Device(config-if)# load-interval 30 Device(config-if)# service-policy output test Device(config-if)# no shutdown Device(config-if)# end
Device# show policy-map interface Serial2/0 Service-policy output: test Class-map: af4 (match-all) 269 packets, 336250 bytes 30 second offered rate 90000 bps, drop rate 13000 bps Match: dscp af41 (34) af42 (36) af43 (38) Queueing queue limit 100 ms/ 2500 bytes queue-limit dscp 34 150 ms/ 3750 bytes (pkts output/bytes output) 179/223750 (pkt drops/byte drops) 0/0 (queue depth/total drops/no-buffer drops) 2500/39/0 (pkts output/bytes output) 230/287500 bandwidth 200 kbps cac local rate 200 kbps, reserved 200 kbps flow rate fixed 100 kbps flow idle-timeout 5 sec All flows: Number of admitted flows: [2] Number of non-admitted flows: [1] Service-policy : child Class-map: admitted (match-all) 178 packets, 222500 bytes 30 second offered rate 60000 bps, drop rate 0000 bps Match: metadata cac status admitted QoS Set dscp af41 Packets marked 194 Class-map: unadmitted (match-all) 88 packets, 110000 bytes 30 second offered rate 30000 bps, drop rate 0000 bps Match: metadata cac status un-admitted QoS Set dscp af42 Packets marked 96 Class-map: class-default (match-any) 3 packets, 3750 bytes 30 second offered rate 1000 bps, drop rate 0000 bps Match: any Class-map: class-default (match-any) 181 packets, 115396 bytes 30 second offered rate 31000 bps, drop rate 0000 bps Match: any queue limit 64 packets (queue depth/total drops/no-buffer drops) 0/0/0 (pkts output/bytes output) 181/115396
Related Topic |
Document Title |
---|---|
Cisco IOS commands |
|
QoS commands: complete command syntax, command modes, command history, defaults, usage guidelines, and examples. |
Cisco IOS Quality of Service Solutions Command Reference |
Description |
Link |
---|---|
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The following table provides release information about the feature or features described in this module. This table lists only the software release that introduced support for a given feature in a given software release train. Unless noted otherwise, subsequent releases of that software release train also support that feature.
Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required.
Feature Name |
Releases |
Feature Information |
---|---|---|
Per-Flow Admission |
15.4(2)T |
The Per-Flow Admission feature provides explicit controls to limit flows in order to protect already admitted flows on the routing/WAN edge. The following commands were introduced by this feature: admit cac local, flow idle-timeout, flow rate fixed, rate. |