Community attribute resolution for "Cisco" BGP

BGP of the Community is a route-tagging method that ensures the continuity of route filtering and selection, and is transitive.

Experimental topology:

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Lab Requirements:

1. Set the 11.0/24 community Property value 100:11 on R1 and pass the property to R3

2. Add another attribute value for 11.11.11.0/24 no-export

 3.   in r1 on network 12.0/24 net segment, according to strict matching principle, in R3 will arrive 12.0/24 metric Span style= "font-family: ' The song Body '; > set to 1111, and 11.0/24 metric

4. Delete the no-export attributeof the 11.0/24 Route on R3 ,12.0 The properties of the/24 are not changed.

Experimental steps:

( 1 ) Complete the basic configuration

R1

Router BGP 100
Neighbor 12.0.0.2 Remote-as 200

R2

Router BGP 200
Neighbor 12.0.0.1 Remote-as 100
Neighbor 23.0.0.3 Remote-as 300

R3

Router BGP 300
Neighbor 23.0.0.2 Remote-as 200

wait for the neighbor to be established. , in the R1 on network11.11.11.0/24 .

R1

Router BGP 100
Network 11.11.11.0 Mask 255.255.255.0

R2,R3 have learned the

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in the R1 on the 11.11.11.0/24 this route adds Community Property Value 100:11 , and make R2,R3 all learn.

R1

IP prefix-list One permit 11.11.11.0/24//prefix list matches this route

Route-map Test Permit 10
Match IP address prefix-list 11
Set Community 100:11

Route-map test per 20

Router BGP 100
Neighbor 12.0.0.2 Send-community
neighbor 12.0.0.2 Route-map test out//apply to Out direction

R2

Router BGP 200

Neighbor 23.0.0.3 send-community//default does not pass the Community attribute, plus this one can pass the

R2,R3 to use the Convert Format command before viewing

R2

IP bgp-community New-format
!

R3

IP bgp-community New-format
!

You can then see the value of this property.

R2/r3

Clear IP b * s

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( 2 ) below in R2 on the 11.11.11.0/24 Add a property No-export ( This attribute means: Do not Pass this route to the EBGP neighbor)

R2

IP community-list Permit 100:11

Route-map Test Permit 10
Match Community 11
Set Community No-export Additive//= Add, overwrite original property without this keyword
!

Route-map Test Permit 20

Router BGP 200
Neighbor 23.0.0.3 Route-map test out

can be in R3 have a look at

R3

Clear IP b * s

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(3) in the R1 on Network 12.0/24 network segment, in R3 Admiral arrives 12.0/24 of the network segment Metric set to 1111.

R1

Router BGP 100
Network 12.12.12.0 Mask 255.255.255.0

R2

No IP community-list 11

IP community-list Permit Internet//All matches
!

R3

IP community-list Permit no-export

Route-map Test Permit 10
Match Community Exact-match//Strictly match no-export, a little bit less
Set metric 1111
!
Route-map Test Permit 20
!

Router BGP 300
Neighbor 23.0.0.2 Route-map Test in

Clear IP b * s

View Results

12.0/24 of the Metric The value has changed, and 11.0/24 is still empty.

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( 4 ) First Look at 11.0/24 and the 12.0/24 the attribute condition

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11.11.11.0/24 Properties: 100:1 , No-export

12.12.12.0/24 Properties: No-export

now the need is to delete 11.11.11.0/24 of the No-export property, other unchanged.

R3

No IP community-list 11

IP community-list Permit 100:11

IP community-list Standard del permit No-export//redefine a property list match No-export property

Route-map Test Permit 10

No match community One Exact-match

Match Community 11
Set metric 1111
set comm-list del delete

View Results

R3:clear IP b * s

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The No-export property of the 11.11.11.0/24 has been removed, the other has not changed, the experiment is over.

This article is from the "Ne Road" blog, please be sure to keep this source http://332162926.blog.51cto.com/8831013/1584648

Community attribute resolution for "Cisco" BGP