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reflect change path attribute for route policy

Created: May 9, 2018 06:28:16Latest reply: Oct 27, 2018 08:17:49 2440 5 0 0 0
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Hi!


This post talks about reflect change path attribute for route policy.

 

I have prepared a project in eNSP, so I have to use reflect change path attribute for IBGP Peer. 


But this command is not present in the router simulator of eNSP, due to which some routes are not exchanging and route policy will not take effect without this command. 


So please let me know if there is an alternative way for route policy to take effect for IBGP Peer.

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Featured Answers
lizhi94
Created Oct 27, 2018 08:17:49

Hi, shehbaz!

     
You can use local-preference of bgp path attribute between ibgp peer and ibgp peer.


The example is as per below:


1. Define the ACL to permit routing that you want to pass to the ibgp peer.

#

acl number 2004


description default-internet


rule 1 permit source 0.0.0.0 0

#


2. Define Route-policy.


#

route-policy test deny node 10


 if-match acl 2004

 

apply local-preference 200


3. Please use route-policy to ibgp peer.


#

ipv4-family unicast

peer 10.10.64.2 as-number 100 route-policy test

#


This is the viewpiont of the configuration. Happy for your acceptance!

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All Answers
StarOfWest
StarOfWest Created May 9, 2018 06:39:20

Hi,

I'm not sure what reflect change path attribute is :), but I know it's possible to change the AS_PATH attribute advertised to an iBGP peer. For instance, you can define a route-policy as below, were we can apply/add additional AS no into the AS_PATH as below. This is useful for AS prepending scenario.

#
route-policy rp1 permit node 10
if-match acl 2008
apply as-path 65530 65530 65530 additive
#

then apply for an internal BGP peer like below:

peer 10.172.183.1 route-policy rp1 export

Then the peer should receive the prefix matching the ACL with AS_PATH BGP attribute changed accordingly with route-policy apply setting.

*> 10.15.188.0/24 10.172.183.2 0 65510 i
* 10.160.29.0/24 10.172.183.2 0 0 65510 65510 65510 65510 i \\\ this prefix will have a worsen metric

For more details, please check this forum thread.

http://forum.huawei.com/enterprise/en/forum.php?mod=viewthread&tid=191037&page=1#pid1082865

I hope this is what you are trying to achieve :).
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shehbaz
shehbaz Created May 9, 2018 06:44:32

Posted by StarOfWest at 2018-05-09 06:39 Hi, I'm not sure what reflect change path attribute is , but I know it's possible to change the AS ...
hi,

thanks for your information......but in route policy I m using below.

route-policy IPV4-TO-PRE-AGG permit node 10
if-match mpls-label
apply ip-address next-hop peer-address
apply mpls-label

peer PRE-AGG route-policy IPV4-TO-PRE-AGG export

so in above command ..........route policy is not taking effect....sp pls in this scenario
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StarOfWest
StarOfWest Created May 10, 2018 07:03:10

Please add one more node to the route-policy

route-policy IPV4-TO-PRE-AGG permit node 10
if-match mpls-label
apply ip-address next-hop peer-address
apply mpls-label
route-policy IPV4-TO-PRE-AGG permit node 20

Then check on the other peer whether the bgp prefixes are shown in the bgp routing table. it may not appear in public routing table because it might not be considered the best.
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shehbaz
shehbaz Created May 11, 2018 05:01:04 (0) (0)
I have checked and after fire this command ....route was flapping continuously on router. 
lizhi94
lizhi94 Created Oct 27, 2018 08:17:49

Hi, shehbaz!

     
You can use local-preference of bgp path attribute between ibgp peer and ibgp peer.


The example is as per below:


1. Define the ACL to permit routing that you want to pass to the ibgp peer.

#

acl number 2004


description default-internet


rule 1 permit source 0.0.0.0 0

#


2. Define Route-policy.


#

route-policy test deny node 10


 if-match acl 2004

 

apply local-preference 200


3. Please use route-policy to ibgp peer.


#

ipv4-family unicast

peer 10.10.64.2 as-number 100 route-policy test

#


This is the viewpiont of the configuration. Happy for your acceptance!

View more
  • x
  • convention:

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