Published On: August 6ᵗʰ, 2019 02:09

IP Routing: Protocol-Independent Configuration Guide, Cisco IOS XE Release 3S

The QoS Policy Propagation via BGP feature allows you to classify packets by IP precedence based on the Border Gateway Protocol (BGP) community lists, BGP autonomous system paths, and access lists. After packets have been classified, you can use other quality of service (QoS) features such as committed access rate (CAR) and Weighted Random Early Detection (WRED) to specify and enforce policies to fit your business model.

Finding Feature Information

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.

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.

Prerequisites for QoS Policy Propagation via BGP

  • Enable the Border Gateway Protocol (BGP) and Cisco Express Forwarding (CEF) or distributed CEF (dCEF) on the device. Subinterfaces on an ATM interface that have the bgp-policy command enabled must use CEF mode because dCEF is not supported. dCEF uses the Versatile Interface Processor (VIP) rather than the Route Switch Processor (RSP) to perform forwarding functions.

  • Define the policy.

  • Apply the policy through BGP.

  • Configure the BGP community list, BGP autonomous system path, or access list and enable the policy on an interface.

  • Enable committed access rate (CAR) or Weighted Random Early Detection (WRED) to use the policy.

Information About QoS Policy Propagation via BGP

Benefits of QoS Policy Propagation via BGP

The QoS Policy Propagation via BGP feature allows you to classify packets by IP precedence based on Border Gateway Protocol (BGP) community lists, BGP autonomous system paths, and access lists. After a packet has been classified, you can use other quality of service (QoS) features such as committed access rate (CAR) and Weighted Random Early Detection (WRED) to specify and enforce policies to fit your business model.

How to Configure QoS Policy Propagation via BGP

Configuring QoS Policy Propagation via BGP Based on Community Lists

SUMMARY STEPS

  1. enable
  2. configure terminal
  3. route-map map-tag [permit | deny ] [sequence-number ] [
  4. match community {standard-list-number | expanded-list-number | community-list-name [exact ]}
  5. set ip precedence [number | name]
  6. exit
  7. router bgp autonomous-system
  8. table-map route-map-name
  9. exit
  10. ip community-list standard-list-number {permit | deny } [community-number]
  11. interface type number
  12. bgp-policy {source | destination } ip-prec-map
  13. exit
  14. ip bgp-community new-format
  15. end

DETAILED STEPS

  Command or Action Purpose
Step 1

enable

Example:


Device> enable

Enables privileged EXEC mode.

  • Enter your password if prompted.

Step 2

configure terminal

Example:


Device# configure terminal

Enters global configuration mode.

Step 3

route-map map-tag [permit | deny ] [sequence-number ] [

Example:


Device(config)# route-map alpha permit ordering-seq 

Configures a route map and specifies how the packets are to be distributed. .

Step 4

match community {standard-list-number | expanded-list-number | community-list-name [exact ]}

Example:


Device(config-route-map)# match community 1

Matches a Border Gateway Protocol (BGP) community list.

Step 5

set ip precedence [number | name]

Example:


Device(config-route-map)# set ip precedence 5

Sets the IP Precedence field when the community list matches.

Note 

You can specify either a precedence number or a precedence name.

Step 6

exit

Example:


Device(config-route-map)# exit

Exits route-map configuration mode and returns to global configuration mode.

Step 7

router bgp autonomous-system

Example:


Device(config)# router bgp 45000

Enables a BGP process and enters router configuration mode.

Step 8

table-map route-map-name

Example:


Device(config-router)# table-map rm1

Modifies the metric and tag values when the IP routing table is updated with BGP learned routes.

Step 9

exit

Example:


Device(config-router)# exit

Exits router configuration mode and returns to global configuration mode.

Step 10

ip community-list standard-list-number {permit | deny } [community-number]

Example:


Device(config)# ip community-list 1 permit 2

Creates a community list for BGP and controls access to it.

Step 11

interface type number

Example:


Device(config)# interface gigabitethernet 0/0/0

Specifies the interface (or subinterface) and enters interface configuration mode.

Step 12

bgp-policy {source | destination } ip-prec-map

Example:


Device(config-if)# bgp-policy source ip-prec-map

Classifies packets using IP precedence.

Step 13

exit

Example:


Device(config-if)# exit

Exits interface configuration mode and returns to global configuration mode.

Step 14

ip bgp-community new-format

Example:


Device(config)# ip bgp-community new-format

(Optional) Displays the BGP community number in AA:NN (autonomous system:community number/4-byte number) format.

Step 15

end

Example:


Device(config)# end

Exits global configuration mode and returns to privileged EXEC mode.

Configuring QoS Policy Propagation via BGP Based on the Autonomous System Path Attribute

SUMMARY STEPS

  1. enable
  2. configure terminal
  3. named-ordering-route-map enable ]
  4. route-map map-tag [permit | deny ] [sequence-number ] [ ordering-seq sequence-name
  5. match as-path path-list-number
  6. set ip precedence [number | name]
  7. exit
  8. router bgp autonomous-system
  9. table-map route-map-name
  10. exit
  11. ip as-path access-list access-list-number {permit | deny } as-regular-expression
  12. interface type number
  13. bgp-policy {source | destination } ip-prec-map
  14. end

DETAILED STEPS

  Command or Action Purpose
Step 1

enable

Example:


Device> enable

Enables privileged EXEC mode.

  • Enter your password if prompted.

Step 2

configure terminal

Example:


Device# configure terminal

Enters global configuration mode.

Step 3

named-ordering-route-map enable ]

Example:


Device(config)# named-ordering-route-map enable

Enables ordering of route-maps based on a string provided by the user.

Step 4

route-map map-tag [permit | deny ] [sequence-number ] [ ordering-seq sequence-name

Example:


Device(config)# route-map alpha permit ordering-seq sequence1

Configures a route map and specifies how the packets are to be distributed. ordering-seq indicates the sequence that is to be used for ordering of route-maps.

Step 5

match as-path path-list-number

Example:

Device(config-route-map)# match as-path 2

Matches a Border Gateway Protocol (BGP) autonomous system path access list.

Step 6

set ip precedence [number | name]

Example:

Device(config-route-map)# set ip precedence 5

Sets the IP Precedence field when the autonomous-system path matches.

Note 

You can specify either a precedence number or a precedence name.

Step 7

exit

Example:

Device(config-route-map)# exit

Exits route-map configuration mode and returns to global configuration mode.

Step 8

router bgp autonomous-system

Example:

Device(config)# router bgp 45000

Enables a BGP process and enters router configuration mode.

Step 9

table-map route-map-name

Example:

Device(config-router)# table-map rm1

Modifies the metric and tag values when the IP routing table is updated with BGP learned routes.

Step 10

exit

Example:

Device(config-router)# exit

Exits router configuration mode and returns to global configuration mode.

Step 11

ip as-path access-list access-list-number {permit | deny } as-regular-expression

Example:

Device(config)# ip as-path access-list 500 permit 45000

Defines an autonomous system path access list.

Step 12

interface type number

Example:

Device(config)# interface gigabitethernet 0/0/0

Specifies the interface (or subinterface) and enters interface configuration mode.

Step 13

bgp-policy {source | destination } ip-prec-map

Example:

Device(config-if)# bgp-policy source ip-prec-map

Classifies packets using IP precedence.

Step 14

end

Example:

Device(config-if)# end

Exits interface configuration mode and returns to privileged EXEC mode.

Configuring QoS Policy Propagation via BGP Based on an Access List

SUMMARY STEPS

  1. enable
  2. configure terminal
  3. named-ordering-route-map enable ]
  4. route-map map-tag [permit | deny ] [sequence-number ] [ ordering-seq sequence-name
  5. match ip address access-list-number
  6. set ip precedence [number | name]
  7. exit
  8. router bgp autonomous-system
  9. table-map route-map-name
  10. exit
  11. access-list access-list-number {permit | deny } source
  12. interface type number
  13. bgp-policy {source | destination } ip-prec-map
  14. end

DETAILED STEPS

  Command or Action Purpose
Step 1

enable

Example:


Device> enable

Enables privileged EXEC mode.

  • Enter your password if prompted.

Step 2

configure terminal

Example:


Device# configure terminal

Enters global configuration mode.

Step 3

named-ordering-route-map enable ]

Example:


Device(config)# named-ordering-route-map enable

Enables ordering of route-maps based on a string provided by the user.

Step 4

route-map map-tag [permit | deny ] [sequence-number ] [ ordering-seq sequence-name

Example:


Device(config)# route-map alpha permit ordering-seq sequence1

Configures a route map and specifies how the packets are to be distributed. ordering-seq indicates the sequence that is to be used for ordering of route-maps.

Step 5

match ip address access-list-number

Example:

Device(config-route-map)# match ip address 69

Matches an access list.

Step 6

set ip precedence [number | name]

Example:

Device(config-route-map)# set ip precedence routine

Sets the IP precedence field when the autonomous system path matches.

Step 7

exit

Example:

Device(config-route-map)# exit

Exits route-map configuration mode and returns to global configuration mode.

Step 8

router bgp autonomous-system

Example:

Device(config)# router bgp 45000

Enables a Border Gateway Protocol (BGP) process and enters router configuration mode.

Step 9

table-map route-map-name

Example:

Device(config-router)# table-map rm1

Modifies the metric and tag values when the IP routing table is updated with BGP learned routes.

Step 10

exit

Example:

Device(config-router)# exit

Exits router configuration mode and returns to global configuration mode.

Step 11

access-list access-list-number {permit | deny } source

Example:

Device(config)# access-list 69 permit 10.69.0.0

Defines an access list.

Step 12

interface type number

Example:

Device(config)# interface gigabitethernet 0/0/0

Specifies the interfaces (or subinterface) and enters interface configuration mode.

Step 13

bgp-policy {source | destination } ip-prec-map

Example:

Device(config-if)# bgp-policy source ip-prec-map

Classifies packets using IP Precedence.

Step 14

end

Example:

Device(config-if)# end

Exits interface configuration mode and returns to privileged EXEC mode.

Monitoring QoS Policy Propagation via BGP

To monitor the QoS Policy Propagation via the BGP feature configuration, use the following optional commands.

Command or Action

Purpose

show ip bgp  

Displays entries in the Border Gateway Protocol (BGP) routing table to verify whether the correct community is set on the prefixes.

show ip bgp community-list  community-list-number 

Displays routes permitted by the BGP community to verify whether correct prefixes are selected.

show ip cef  network 

Displays entries in the forwarding information base (FIB) table based on the specified IP address to verify whether Cisco Express Forwarding has the correct precedence value for the prefix.

show ip interface  

Displays information about the interface.

show ip route  prefix 

Displays the current status of the routing table to verify whether correct precedence values are set on the prefixes.

Configuration Examples for QoS Policy Propagation via BGP

Example: Configuring QoS Policy Propagation via BGP

The following example shows how to create route maps to match access lists, Border Gateway Protocol (BGP) community lists, and BGP autonomous system paths, and apply IP precedence to routes learned from neighbors.

In the figure below, Device A learns routes from autonomous system 10 and autonomous system 60. The quality of service (QoS) policy is applied to all packets that match defined route maps. Any packets from Device A to autonomous system 10 or autonomous system 60 are sent the appropriate QoS policy, as the numbered steps in the figure indicate.

Figure 1. Device Learning Routes and Applying QoS Policy

Device A Configuration


interface serial 5/0/0/1:0
ip address 10.28.38.2 255.255.255.0
bgp-policy destination ip-prec-map
no ip mroute-cache
no cdp enable
frame-relay interface-dlci 20 IETF
router bgp 30
 table-map precedence-map
 neighbor 10.20.20.1 remote-as 10
 neighbor 10.20.20.1 send-community
!
ip bgp-community new-format
!
! Match community 1 and set the IP precedence to priority
route-map precedence-map permit 10
 match community 1
 set ip precedence priority
!
! Match community 2 and set the IP precedence to immediate
route-map precedence-map permit 20
 match community 2
 set ip precedence immediate
!
! Match community 3 and set the IP precedence to flash
route-map precedence-map permit 30
 match community 3
 set ip precedence flash
!
! Match community 4 and set the IP precedence to flash-override
route-map precedence-map permit 40
 match community 4
 set ip precedence flash-override
!
! Match community 5 and set the IP precedence to critical
route-map precedence-map permit 50
 match community 5
 set ip precedence critical
!
! Match community 6 and set the IP precedence to internet
route-map precedence-map permit 60
 match community 6
 set ip precedence internet
!
! Match community 7 and set the IP precedence to network
route-map precedence-map permit 70
 match community 7
 set ip precedence network
!
! Match ip address access list 69 or match autonomous system path 1
! and set the IP precedence to critical
route-map precedence-map permit 75
 match ip address 69
 match as-path 1
 set ip precedence critical
!
! For everything else, set the IP precedence to routine
route-map precedence-map permit 80
 set ip precedence routine
!
! Define community lists 
ip community-list 1 permit 60:1
ip community-list 2 permit 60:2
ip community-list 3 permit 60:3
ip community-list 4 permit 60:4
ip community-list 5 permit 60:5
ip community-list 6 permit 60:6
ip community-list 7 permit 60:7
!
! Define the AS path
ip as-path access-list 1 permit ^10_60
!
! Define the access list
access-list 69 permit 10.69.0.0

Device B Configuration


router bgp 10
 neighbor 10.30.30.1 remote-as 30
 neighbor 10.30.30.1 send-community
 neighbor 10.30.30.1 route-map send_community out
!
ip bgp-community new-format
!
! Match prefix 10 and set community to 60:1
route-map send_community permit 10
 match ip address 10
 set community 60:1
!
! Match prefix 20 and set community to 60:2
route-map send_community permit 20
 match ip address 20
 set community 60:2
!
! Match prefix 30 and set community to 60:3
route-map send_community permit 30
 match ip address 30
 set community 60:3
!
! Match prefix 40 and set community to 60:4
route-map send_community permit 40
 match ip address 40
 set community 60:4
!
! Match prefix 50 and set community to 60:5
route-map send_community permit 50
 match ip address 50
 set community 60:5
!
! Match prefix 60 and set community to 60:6
route-map send_community permit 60
 match ip address 60
 set community 60:6
!
! Match prefix 70 and set community to 60:7
route-map send_community permit 70
 match ip address 70
 set community 60:7
!
! For all others, set community to 60:8
route-map send_community permit 80
 set community 60:8
!
! Define access lists
access-list 10 permit 10.61.0.0
access-list 20 permit 10.62.0.0
access-list 30 permit 10.63.0.0
access-list 40 permit 10.64.0.0
access-list 50 permit 10.65.0.0
access-list 60 permit 10.66.0.0
access-list 70 permit 10.67.0.0

Additional References

Related Documents

Related Topic

Document Title

Cisco IOS commands

Cisco IOS Master Command List, All Releases

IP routing protocol-independent commands

Cisco IOS IP Routing: Protocol-Independent Command Reference

BGP configuration

BGP Configuration Guide

Cisco Express Forwarding configuration

Cisco Express Forwarding Configuration Guide

Committed access rate configuration

“Configuring Committed Access Rate” module in the QoS: Classification Configuration Guide (part of the Quality of Service Solutions Configuration Guide Library)

Weighted Random Early Detection configuration

“Configuring Weighted Random Early Detection” module in the QoS: Congestion Avoidance Configuration Guide (part of the Quality of Service Solutions Configuration Guide Library)

Technical Assistance

Description

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http://www.cisco.com/cisco/web/support/index.html

Feature Information for QoS Policy Propagation via BGP

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.
Table 1. Feature Information for QoS Policy Propagation via BGP

Feature Name

Releases

Feature Information

QoS Policy Propagation via BGP

The QoS Policy Propagation via BGP feature allows you to classify packets by IP precedence based on Border Gateway Protocol (BGP) community lists, BGP autonomous system paths, and access lists. After a packet has been classified, you can use other quality of service (QoS) features such as committed access rate (CAR) and Weighted Random Early Detection (WRED) to specify and enforce policies to fit your business model.

Policy Routing Infrastructure

The Policy Routing Infrastructure feature provides full support of IP policy-based routing with Cisco Express Forwarding (CEF). As CEF gradually obsoletes fast switching, policy routing is integrated with CEF to increase customer performance requirements. When policy routing is enabled, redundant processing is avoided.