Configuring QoS Policy Propagation via Border Gateway Protocol

To configure Policy Propagation via BGP, perform the following basic tasks:

• Configure BGP and Cisco Express Forwarding (CEF) or distributed CEF (dCEF). To configure BGP, refer to the Cisco IOS IP and IP Routing Configuration Guide. To configure CEF and dCEF, refer to the Cisco IOS Switching Services Configuration Guide.

• 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. For information about this task, see the next section in this chapter.

• Enable CAR or WRED to use the policy. To enable CAR, see the chapter "Configuring Committed Access Rate" in this book. To configure WRED, see the chapter "Configuring Weighted Random Early Detection" in this book.

This chapter describes how to configure Policy Propagation based on BGP community list, BGP autonomous system path, or access list. It assumes you have already configured BGP and CEF or dCEF.

To configure the router to propagate the IP Precedence based on the community lists, use the following commands beginning in global configuration mode:

	Command	Purpose
Step 1	route-map route-map-name [permit | deny [sequence-number]]	Defines a route map to control redistribution and enter route-map configuration mode.
Step 2	match community-list community-list-number [exact]	Matches a BGP community list.
Step 3	set ip precedence [number | name]	Sets the IP Precedence field when the community list matches. You can specify either a precedence number or name.
Step 4	router bgp autonomous-system	Enters router configuration mode.
Step 5	table-map route-map-name	Modifies the metric and tag values when the IP routing table is updated with BGP learned routes.
Step 6	ip community-list community-list-number {permit | deny} community-number	Creates a community list for BGP and controls access to it.
Step 7	interface interface-type interface-number	Specifies the interfaces (or subinterface) and enters interface configuration mode.
Step 8	bgp-policy ip-prec-map	Classifies packets using IP Precedence.
Step 9	ip bgp-community new-format	(Optional) Configures a new community format so that the community number is displayed in the short form.
Step 10	end	Exits configuration mode.

To configure the router to propagate the IP Precedence based on the autonomous system path attribute, use the following commands beginning in global configuration mode:

	Command	Purpose
Step 1	route-map route-map-name [permit | deny [sequence-number]]	Defines a route map to control redistribution and enter route-map configuration mode.
Step 2	match as-path path-list-number	Matches a BGP autonomous system path access list.
Step 3	set ip precedence [number | name]	Sets the IP Precedence field when the autonomous system path matches. Specifies either a precedence number or name.
Step 4	router bgp autonomous-system	Enters router configuration mode.
Step 5	table-map route-map-name	Modifies the metric and tag values when the IP routing table is updated with BGP learned routes.
Step 6	ip as-path access-list access-list-number {permit | deny} as-regular-expression	Defines an autonomous system path access list.
Step 7	interface interface-type interface-number	Specifies the interfaces (or subinterface) and enters interface configuration mode.
Step 8	bgp-policy ip-prec-map	Classifies packets using IP Precedence.
Step 9	end	Exits configuration mode.

To configure the router to propagate the IP Precedence based on an access list, use the following commands beginning in global configuration mode:

	Command	Purpose
Step 1	route-map route-map-name [permit | deny [sequence-number]]	Defines a route map to control redistribution and enter route-map configuration mode.
Step 2	match ip address access-list-number	Matches an access list.
Step 3	set ip precedence [number | name]	Sets the IP Precedence field when the autonomous system path matches.
Step 4	router bgp autonomous-system	Enters router configuration mode.
Step 5	table-map route-map-name	Modifies the metric and tag values when the IP routing table is updated with BGP learned routes.
Step 6	access-list access-list-number {permit | deny} source	Defines an access list.
Step 7	interface interface-type interface-number	Specifies the interfaces (or subinterface) and enters interface configuration mode.
Step 8	bgp-policy ip-prec-map	Classifies packets using IP Precedence.
Step 9	end	Exits configuration mode.

Router A Configuration

router bgp 30
 table-map precedence-map
 neighbor 20.20.20.1 remote-as 10
 neighbor 20.20.20.1 send-community
 neighbor 20.20.20.1 route-map precedence-map out
!
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 AS 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 the 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 69.0.0.0

Router B Configuration

router bgp 10
 neighbor 30.30.30.1 remote-as 30
 neighbor 30.30.30.1 send-community
 neighbor 30.30.30.1 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 the access lists
access-list 10 permit 61.0.0.0
access-list 20 permit 62.0.0.0
access-list 30 permit 63.0.0.0
access-list 40 permit 64.0.0.0
access-list 50 permit 65.0.0.0
access-list 60 permit 66.0.0.0
access-list 70 permit 67.0.0.0