Accumulated Interior Gateway Protocol

OcNOS-SP : Layer 3 Guide : Layer 3 Unicast Configuration Guide : BGP : Accumulated Interior Gateway Protocol

Overview

This section includes step-by-step configuration of AIGP Metric Attribute for BGP It also contains an overview of the concepts of AIGP. AIGP is a non-transitive attribute that includes the accumulated IGP metric. BGP routers advertise this AIGP metric to neighbors in other ASes. This allows BGP routers to select the best path based on the end-to-end IGP metric.

Topology

The diagram depicts the topology for the configuration examples that follow.

Figure 1-41: Accumulated Interior Gateway Protocol

Base Configurations

Loopback Interface:

#configure terminal	Enter configuration mode.
(config)#interface lo	Enter the Interface mode for the loopback interface.
(config-if)#ip address 1.1.1.1/32 secondary	Configure IP address on loopback interface.
(config-if)#commit	Commit the transaction

Interface Configuration:

(config)#interface xe15	Enter the Interface mode for xe15.
(config-if)# ip address 10.10.10.1/24	Configure IP address on the interface.
(config-if)#exit	Exit interface mode
(config)#interface xe13	Enter the Interface mode for xe13.
(config-if)# ip address 11.11.11.1/24	Configure IP address on the interface.
(config)#interface xe12	Enter the Interface mode for xe12.
(config-if)# ip address 50.50.50.2/24	Configure IP address on the interface.
(config-if)#commit	Commit the transaction.

OSPF Configuration:

(config)#router ospf 100	Enter the Router OSPF mode.
(config-router)#ospf router-id 1.1.1.1	Router-id configurations
(config-router)# network 1.1.1.1/32 area 0	Advertise loopback address in OSPF.
(config-router)#network 10.10.10.0/24 area 0	Advertise network address in OSPF.
(config-router)#network 11.11.11.0/24 area 0	Advertise network address in OSPF.
(config-router)#commit	Commit the transaction

Loopback Interface:

#configure terminal	Enter configuration mode.
(config)#interface lo	Enter the Interface mode for the loopback interface.
(config-if)#ip address 2.2.2.2/32 secondary	Configure IP address on loopback interface.
(config-if)#commit	Commit the transaction

Interface Configuration:

(config)#interface ce4/4	Enter the Interface mode for ce4/4.
(config-if)# ip address 10.10.10.2/24	Configure IP address on the interface.
(config-if)#interface ce4/1	Enter the Interface mode for ce4/1.
(config-if)# ip address 12.12.12.1/24	Configure IP address on the interface.
(config-if)#interface ce3/2	Enter the Interface mode for ce3/2.
(config-if)# ip address 13.13.13.1/24	Configure IP address on the interface.
(config-if)#commit	Commit the transaction.

OSPF Configuration:

(config)#router ospf 100	Enter the Router OSPF mode.
(config-router)#ospf router-id 2.2.2.2	Router-id configurations
(config-router)# network 2.2.2.2/32 area 0	Advertise loopback address in OSPF.
(config-router)#network 10.10.10.0/24 area 0	Advertise network address in OSPF.
(config-router)#network 12.12.12.0/24 area 0	Advertise network address in OSPF.
(config-router)#network 13.13.13.0/24 area 0	Advertise network address in OSPF.
(config-router)#commit	Commit the transaction

Loopback Interface:

#configure terminal	Enter configuration mode.
(config)#interface lo	Enter the Interface mode for the loopback interface.
(config-if)#ip address 3.3.3.3/32 secondary	Configure IP address on loopback interface.
(config-if)#commit	Commit the transaction

Interface Configuration:

(config)#interface xe4	Enter the Interface mode for xe4.
(config-if)# ip address 11.11.11.2/24	Configure IP address on the interface.
(config)#interface xe2	Enter the Interface mode for xe2.
(config-if)# ip address 12.12.12.2/24	Configure IP address on the interface.
(config-if)#commit	Commit the transaction.

OSPF Configuration:

(config)#router ospf 100	Enter the Router OSPF mode.
(config-router)#ospf router-I 3.3.3.3	Router-id configurations
(config-router)# network 3.3.3.3/32 area 0	Advertise loopback address in OSPF.
(config-router)#network 11.11.11.0/24 area 0	Advertise network address in OSPF.
(config-router)#network 12.12.12.0/24 area 0	Advertise network address in OSPF.
(config-router)#commit	Commit the transaction

Loopback Interface:

#configure terminal	Enter configuration mode.
(config)#interface lo	Enter the Interface mode for the loopback interface.
(config-if)#ip address 4.4.4.4/32 secondary	Configure IP address on loopback interface.
(config-if)#commit	Commit the transaction

Interface Configuration:

(config)#interface xe12	Enter the Interface mode for xe21.
(config-if)# ip address 13.13.13.2/24	Configure IP address on the interface.
(config-if)#commit	Commit the transaction.

OSPF Configuration:

(config)#router ospf 100	Enter the Router OSPF mode.
(config-router)#ospf router-id 4.4.4.4	Router-id configurations
(config-router)# network 4.4.4.4/32 area 0	Advertise loopback address in OSPF.
(config-router)#network 13.13.13.0/24 area 0	Advertise network address in OSPF.
(config-router)#commit	Commit the transaction

BGP Configurations

Route Map Configuration:

(config)# route-map map1 permit 10	Configure route-map map1 with sequence number 10.
(config-route-map)#set aigp-metric 100	Set aigp metric as 100.
(config-route-map)#commit	Commit the transaction

BGP Configuration:

(config)# router bgp 100	Enter the BGP configuration mode.
(config-router)# neighbor 3.3.3.3 remote-as 100	Configure neighbor
(config-router)# neighbor 3.3.3.3 update-source 1.1.1.1	Update loopback address as source
(config-router)# address-family ipv4 unicast	Enter address family mode.
(config-router)#network 50.50.50.0/24 route-map map1	Apply a route map to routes.
(config-router-af)#neighbor 3.3.3.3 activate	Activate the neighbor.
(config-router-af)#exit	Exit address family mode.
(config-router)#exit	Exit Router BGP mode

BGP Configuration:

(config)# router bgp 200	Enter the BGP configuration mode.
(config-router)#neighbor 3.3.3.3 remote-as 100	Configure neighbor
(config-router)#neighbor 4.4.4.4 remote-as 200	Configure neighbor
(config-router)# neighbor 3.3.3.3 update-source 2.2.2.2	Update loopback address as source
(config-router)# neighbor 4.4.4.4 update-source 2.2.2.2	Update loopback address as source
(config-router)# neighbor 3.3.3.3 ebgp-multihop 2	Enable multihop on eBGP session.
(config-router)#address-family ipv4	Enter address family mode.
(config-router-af)#neighbor 3.3.3.3 activate	Activate the neighbor.
(config-router-af)#neighbor 4.4.4.4 activate	Activate the neighbor.
(config-router-af)#neighbor 3.3.3.3 aigp enable	Enable aigp for the neighbor.
(config-router-af)#neighbor 4.4.4.4 aigp enable	Enable aigp for the neighbor.
(config-router-af)#neighbor 4.4.4.4 next-hop-self	Configure next-hop-self for the R4 neighbor.
(config-router-af)#commit	Commit the transaction.

BGP Configuration:

(config)# router bgp 100	Enter the BGP configuration mode.
(config-router)#neighbor 1.1.1.1 remote-as 100	Configure neighbor
(config-router)#neighbor 2.2.2.2 remote-as 200	Configure neighbor
(config-router)#neighbor 4.4.4.4 remote-as 200	Configure neighbor
(config-router)#neighbor 1.1.1.1 update-source 3.3.3.3	Update loopback address as source
(config-router)#neighbor 2.2.2.2 update-source 3.3.3.3	Update loopback address as source
(config-router)#neighbor 4.4.4.4 update-source 3.3.3.3	Update loopback address as source
(config-router)# neighbor 2.2.2.2 ebgp-multihop 2	Enable multihop on eBGP session.
(config-router)# neighbor 4.4.4.4 ebgp-multihop 2	Enable multihop on eBGP session.
(config-router)#address-family ipv4	Enter address family mode.
(config-router-af)#neighbor 1.1.1.1 activate	Activate the neighbor.
(config-router-af)#neighbor 2.2.2.2 activate	Activate the neighbor.
(config-router-af)#neighbor 4.4.4.4 activate	Activate the neighbor.
(config-router-af)#neighbor 2.2.2.2 aigp enable	Enable aigp for the neighbor.
(config-router-af)#neighbor 4.4.4.4 aigp enable	Enable aigp for the neighbor.
(config-router-af)#commit	Exit address family mode.

BGP Configuration:

(config)# router bgp 200	Enter the BGP configuration mode.
(config-router)#neighbor 3.3.3.3 remote-as 100	Configure neighbor
(config-router)#neighbor 2.2.2.2 remote-as 200	Configure neighbor
(config-router)# neighbor 3.3.3.3 update-source 4.4.4.4	Update loopback address as source
(config-router)# neighbor 2.2.2.2 update-source 4.4.4.4	Update loopback address as source
(config-router)# neighbor 3.3.3.3 ebgp-multihop 2	Enable multihop on eBGP session.
(config-router)#address-family ipv4	Enter address family mode.
(config-router-af)#neighbor 3.3.3.3 activate	Activate the neighbor.
(config-router-af)#neighbor 2.2.2.2 activate	Activate the neighbor.
(config-router-af)#neighbor 3.3.3.3 aigp enable	Enable aigp for the neighbor.
(config-router-af)#neighbor 2.2.2.2 aigp enable	Enable aigp for the neighbor.
(config-router-af)#neighbor 2.2.2.2 next-hop-self	Configure next-hop-self for the R4 neighbor.
(config-router-af)#commit	Commit the transaction.

Validation

R3#sh ip ospf neighbor

Total number of full neighbors: 2

OSPF process 100 VRF(default):

Neighbor ID Pri State Dead Time Address Interface Instance ID

1.1.1.1 1 Full/DR 00:00:37 11.11.11.1 xe4 0

2.2.2.2 1 Full/Backup 00:00:37 12.12.12.1 xe2 0

R3#sh ip bgp summary

BGP router identifier 3.3.3.3, local AS number 100

BGP table version is 23

1 BGP AS-PATH entries

0 BGP community entries

Neighbor V AS MsgRcv MsgSen TblVer InQ OutQ Up/Down State/PfxRcd

1.1.1.1 4 100 162 172 23 0 0 00:23:34 1

2.2.2.2 4 200 60 68 23 0 0 00:08:50 0

4.4.4.4 4 200 145 164 23 0 0 00:03:19 0

Total number of neighbors 3

Total number of Established sessions 3

R3#sh ip bgp

BGP table version is 23, local router ID is 3.3.3.3

Status codes: s suppressed, d damped, h history, a add-path, * valid, > best, i - internal,

l - labeled, S Stale

Origin codes: i - IGP, e - EGP, ? - incomplete

Network Next Hop Metric LocPrf Weight Path

*>i 50.50.50.0/24 1.1.1.1 0 100 0 i

Total number of prefixes 1

R3#sh ip bgp 50.50.50.0

BGP routing table entry for 50.50.50.0/24

Paths: (1 available, best #1, table Default-IP-Routing-Table)

Advertised to non peer-group peers:

2.2.2.2 4.4.4.4

Local

Nexthop:1.1.1.1 (metric 2) from 1.1.1.1 (Remote Id:1.1.1.1)

Origin IGP, metric 0, localpref 100, aigp metric 100 valid, internal, best, source safi: 1

Not advertised to any peer

Total AIGP metric 102

Last update: Wed Jun 22 06:41:17 2022

R4#sh ip ospf neighbor

Total number of full neighbors: 1

OSPF process 100 VRF(default):

Neighbor ID Pri State Dead Time Address Interface Instance ID

2.2.2.2 1 Full/Backup 00:00:37 13.13.13.1 xe21 0

R4#sh ip bgp summary

BGP router identifier 4.4.4.4, local AS number 200

BGP table version is 4

2 BGP AS-PATH entries

0 BGP community entries

Neighbor V AS MsgRcv MsgSen TblVer InQ OutQ Up/Down State/PfxRcd

2.2.2.2 4 200 82 85 4 0 0 00:04:28 1

3.3.3.3 4 100 100 96 4 0 0 00:04:28 1

Total number of neighbors 2

Total number of Established sessions 2

R4#sh ip bgp

BGP table version is 4, local router ID is 4.4.4.4

Status codes: s suppressed, d damped, h history, a add-path, * valid, > best, i - internal,

l - labeled, S Stale

Origin codes: i - IGP, e - EGP, ? - incomplete

Network Next Hop Metric LocPrf Weight Path

*> 50.50.50.0/24 3.3.3.3 0 100 0 100 i

* i 2.2.2.2 0 100 0 100 i

Total number of prefixes 1

R4#sh ip bgp 50.50.50.0

BGP routing table entry for 50.50.50.0/24

Paths: (2 available, best #1, table Default-IP-Routing-Table)

Advertised to non peer-group peers:

2.2.2.2

AS path:100

Nexthop:3.3.3.3 (metric 3) from 3.3.3.3 (Remote Id:3.3.3.3)

Origin IGP, metric 0, localpref 100, aigp metric 102 valid, external, best, source safi: 1

Not advertised to any peer

Total AIGP metric 105

Last update: Wed Jun 22 06:57:49 2022

AS path:100

Nexthop:2.2.2.2 (metric 2) from 2.2.2.2 (Remote Id:2.2.2.2)

Origin IGP, metric 0, localpref 100, aigp metric 104 valid, internal, source safi: 1

Not advertised to any peer

Total AIGP metric 106

Last update: Wed Jun 22 06:57:53 2022

R4#

Extended Community Attribute

Follow the base configuration as mentioned above.

Route Map Configuration:

(config)# route-map map1 permit 10	Configure route-map map1 with sequence number 10.
(config-route-map)#set aigp-metric 100	Set aigp metric as 100.
(config)# route-map map2 permit 20	Configure route-map map2 with sequence number 20.
(config-route-map)#set aigp-metric igp-metric	Set aigp metric as igp-metric.
(config-route-map)#commit	Commit the transaction

BGP Configuration:

(config)# router bgp 100	Enter the BGP configuration mode.
(config-router)# neighbor 3.3.3.3 remote-as 100	Configure neighbor
(config-router)# neighbor 2.2.2.2 remote-as 100	Configure neighbor
(config-router)# neighbor 3.3.3.3 update-source 1.1.1.1	Update loopback address as source
(config-router)# neighbor 2.2.2.2 update-source 1.1.1.1	Update loopback address as source
(config-router)# address-family ipv4 unicast	Enter address family mode.
(config-router)#network 50.50.50.0/24	Advertise the network.
(config-router-af)#neighbor 3.3.3.3 activate	Activate the neighbor.
(config-router-af)#neighbor 2.2.2.2 activate	Activate the neighbor.
(config-router-af)#neighbor 3.3.3.3 route-map map1 out	Attach the route-map map1 for the neighbor 3.3.3.3 in out direction
(config-router-af)#neighbor 2.2.2.2 route-map map2 out	Attach the route-map map2 for the neighbor 2.2.2.2 in out direction
(config-router-af)#neighbor 3.3.3.3 aigp disable	Disable the aigp neighbor.
(config-router-af)#neighbor 2.2.2.2 aigp disable	Disable the aigp neighbor.
config-router-af)#neighbor 2.2.2.2 aigp send cost-community 10 poi igp-cost	Enable extended community attribute for the neighbor.
config-router-af)#neighbor 3.3.3.3 aigp send cost-community 10 poi pre-bestpath	Enable extended community attribute for the neighbor.
(config-router-af)#commit	Commit the transaction.

BGP Configuration:

(config)# router bgp 100	Enter the BGP configuration mode.
(config-router)# neighbor 3.3.3.3 remote-as 100	Configure neighbor
(config-router)# neighbor 1.1.1.1 remote-as 100	Configure neighbor
(config-router)# neighbor 4.4.4.4 remote-as 200	Configure neighbor
(config-router)# neighbor 3.3.3.3 update-source 2.2.2.2	Update loopback address as source
(config-router)# neighbor 1.1.1.1 update-source 2.2.2.2	Update loopback address as source
(config-router)# neighbor 4.4.4.4 update-source 2.2.2.2	Update loopback address as source
(config-router)# neighbor 4.4.4.4 ebgp-multihop 2	Enable multihop on eBGP session.
(config-router)# address-family ipv4 unicast	Enter address family mode.
(config-router-af)#neighbor 3.3.3.3 activate	Activate the neighbor.
(config-router-af)#neighbor 1.1.1.1 activate	Activate the neighbor.
(config-router-af)#neighbor 4.4.4.4 activate	Activate the neighbor.
(config-router-af)#commit	Exit address family mode.

BGP Configuration:

(config)# router bgp 100	Enter the BGP configuration mode.
(config-router)#neighbor 1.1.1.1 remote-as 100	Configure neighbor
(config-router)#neighbor 2.2.2.2 remote-as 100	Configure neighbor
(config-router)#neighbor 4.4.4.4 remote-as 200	Configure neighbor
(config-router)#neighbor 1.1.1.1 update-source 3.3.3.3	Update loopback address as source
(config-router)#neighbor 2.2.2.2 update-source 3.3.3.3	Update loopback address as source
(config-router)#neighbor 4.4.4.4 update-source 3.3.3.3	Update loopback address as source
(config-router)# neighbor 4.4.4.4 ebgp-multihop 2	Enable multihop on eBGP session.
(config-router)#address-family ipv4	Enter address family mode.
(config-router-af)#neighbor 1.1.1.1 activate	Activate the neighbor.
(config-router-af)#neighbor 2.2.2.2 activate	Activate the neighbor.
(config-router-af)#neighbor 4.4.4.4 activate	Activate the neighbor.
(config-router-af)#commit	Exit address family mode.

BGP Configuration:

(config)# router bgp 200	Enter the BGP configuration mode.
(config-router)#neighbor 3.3.3.3 remote-as 100	Configure neighbor
(config-router)#neighbor 2.2.2.2 remote-as 100	Configure neighbor
(config-router)# neighbor 3.3.3.3 update-source 4.4.4.4	Update loopback address as source
(config-router)# neighbor 2.2.2.2 update-source 4.4.4.4	Update loopback address as source
(config-router)# neighbor 3.3.3.3 ebgp-multihop 2	Enable multihop on eBGP session.
(config-router)# neighbor 2.2.2.2 ebgp-multihop 2	Enable multihop on eBGP session.
(config-router)#address-family ipv4	Enter address family mode.
(config-router-af)#neighbor 3.3.3.3 activate	Activate the neighbor.
(config-router-af)#neighbor 2.2.2.2 activate	Activate the neighbor.
(config-router-af)#commit	Commit the transaction.

Validation

R4#show ip bgp summary

BGP router identifier 4.4.4.4, local AS number 200

BGP table version is 4

1 BGP AS-PATH entries

0 BGP community entries

Neighbor V AS MsgRcv MsgSen TblVer InQ OutQ Up/Down State/PfxRcd

2.2.2.2 4 100 164 157 4 0 0 00:02:43 1

3.3.3.3 4 100 177 194 4 0 0 00:00:28 1

Total number of neighbors 2

Total number of Established sessions 2

R4#show ip bgp

BGP table version is 4, local router ID is 4.4.4.4

Status codes: s suppressed, d damped, h history, a add-path, * valid, > best, i - internal,

l - labeled, S Stale

Origin codes: i - IGP, e - EGP, ? - incomplete

Network Next Hop Metric LocPrf Weight Path

*> 50.50.50.0/24 2.2.2.2 0 100 0 100 i

* 3.3.3.3 0 100 0 100 i

Total number of prefixes 1

R4#show ip bgp 50.50.50.0

BGP routing table entry for 50.50.50.0/24

Paths: (2 available, best #1, table Default-IP-Routing-Table)

Advertised to non peer-group peers:

3.3.3.3

AS path:100

Nexthop:2.2.2.2 (metric 2) from 2.2.2.2 (Remote Id:2.2.2.2)

Origin IGP, metric 0, localpref 100 valid, external, best, source safi: 1

Extended Community:

cost(transitive)igp_metric:10:0

Not advertised to any peer

Last update: Wed Jun 22 17:57:32 2022

AS path:100

Nexthop:3.3.3.3 (metric 3) from 3.3.3.3 (Remote Id:3.3.3.3)

Origin IGP, metric 0, localpref 100 valid, external, source safi: 1

Extended Community:

cost(transitive)pre-bestpath:10:200

Not advertised to any peer

Last update: Wed Jun 22 17:59:46 2022

Last modified date: 08/28/2023