43. Aggregation Aggregate-address of BGP configuration experiment

1. Experimental topology

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2. Basic Configuration

R1 Configuration

Interface Loopback0

IP Address 1.1.1.1 255.255.255.0

Interface serial0/0

IP address 13.1.1.1 255.255.255.0

Interface fastethernet1/0

IP address 124.1.1.1 255.255.255.0

router OSPF 110

Log-adjacency-changes

Network 1.1.1.0 0.0.0.255 Area 0

Network 124.1.1.0 0.0.0.255 Area 0

Router BGP 1

No synchronization

BGP Router-id 1.1.1.1

Neighbor 2.2.2.2 Remote-as 1

Neighbor 2.2.2.2 Update-source Loopback0

Neighbor 2.2.2.2 Next-hop-self

Neighbor 13.1.1.3 Remote-as 3

No auto-summary

R2 Configuration

Interface Loopback0

IP address 2.2.2.2 255.255.255.0

Interface fastethernet1/0

IP address 124.1.1.2 255.255.255.0

router OSPF 110

Log-adjacency-changes

Network 2.2.2.0 0.0.0.255 Area 0

Network 124.1.1.0 0.0.0.255 Area 0

Router BGP 1

No synchronization

BGP Router-id 2.2.2.2

BGP log-neighbor-changes

Neighbor 1.1.1.1 Remote-as 1

Neighbor 1.1.1.1 Update-source Loopback0

Neighbor 124.1.1.4 Remote-as 4

No auto-summary

R3 Configuration

Interface Loopback0

IP address 3.3.3.3 255.255.255.0

Interface Loopback16

IP address 202.1.16.3 255.255.255.0

Interface Loopback17

IP address 202.1.17.3 255.255.255.0

Interface Loopback18

IP address 202.1.18.3 255.255.255.0

Interface Loopback19

IP address 202.1.19.3 255.255.255.0

Interface serial0/0

IP address 13.1.1.3 255.255.255.0

Router BGP 3

No synchronization

BGP Router-id 3.3.3.3

BGP log-neighbor-changes

Network 3.3.3.0 Mask 255.255.255.0

Network 202.1.16.0

Network 202.1.17.0

Network 202.1.18.0

Network 202.1.19.0

Neighbor 13.1.1.1 Remote-as 1

No auto-summary

R4 Configuration

Interface Loopback0

IP address 4.4.4.4 255.255.255.0

Interface fastethernet1/0

IP address 124.1.1.4 255.255.255.0

Router BGP 4

No synchronization

BGP Router-id 4.4.4.4

BGP log-neighbor-changes

Network 4.4.4.0 Mask 255.255.255.0

Neighbor 124.1.1.2 Remote-as 1

No auto-summary

3. Configuring aggregations

There are two ways to use BGP aggregation:

Method One: Manually write a static summary route that points to an empty interface, and then publish the rollup route in the BGP routing process rollup

Method Two: First in the BGP routing process in the network all the detailed route, in the Aggregate-address 202.1.16.0 255.255.252.0 to do the aggregation, this time will be aggregated routing and detailed routing are advertised, Aggregate-address 202.1.16.0 255.255.252.0 Summary-only will suppress the detail route, which is identified as s, and is not sent to other BGP neighbors.

In addition, we can specify that no specific route is advertised, the basic steps are as follows:

IP prefix-list 1 Permit 202.1.16.0/23 GE 24 le

Route-map YZ Permit 10

Match IP Address prefix-list 1

Router BGP 3

Aggregate-address 202.1.16.0 255.255.252.0 Suppress-map YZ

The second method is to do the aggregation in the sender, if the receiver does the aggregation, the receiver generates the aggregation route will be reversed to the sender, this will result in packet loss, so should not let the aggregation route callback. To achieve the purpose of non-transmission, we use the BGP horizontal segmentation technology, the aggregation route to add the attributes of the detail route, so that when the sender receives the aggregation route, because the aggregation route carries its own as number and does not accept the route, Aggregate-address 202.1.16.0 255.255.252.0 summary-only As-set.

Method One:

R3 Configuration

IP Route 202.1.16.0 255.255.252.0 null0

Router BGP 3

No network 202.1.16.0

No network 202.1.17.0

No network 202.1.18.0

No network 202.1.19.0

Network 202.1.16.0 Mask 255.255.252.0

Method Two:

R3 Configuration

No IP route 202.1.16.0 255.255.252.0 null0

Router BGP 3

No Network 202.1.16.0 Mask 255.255.252.0

Network 202.1.16.0

Network 202.1.17.0

Network 202.1.18.0

Network 202.1.19.0

Aggregate-address 202.1.16.0 255.255.252.0

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Aggregate-address 202.1.16.0 255.255.252.0 Summary-only will suppress the detail route, which is identified as s, and is not sent to other BGP neighbors.

Router BGP 3

Aggregate-address 202.1.16.0 255.255.252.0 summary-only

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Clears the aggregations on the R3 and aggregates them on the R1.

Router BGP 3

No aggregate-address 202.1.16.0 255.255.252.0 summary-only

Router BGP 1

No aggregate-address 202.1.16.0 255.255.252.0 summary-only

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Router BGP 1

No aggregate-address 202.1.16.0 255.255.252.0 summary-only as-set

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R1 no longer advertises the aggregation route to R3.

This article is from the "Open Source Hall" blog, please be sure to keep this source http://kaiyuandiantang.blog.51cto.com/10699754/1721234

43. Aggregation Aggregate-address of BGP configuration experiment