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Regular Visitor
Posts: 8
Registered: ‎06-30-2016
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Reg BGP inbound traffic through particular ISP

HI,

We have terminated two ISP links and Google peering link in our MX104 . We have two MX-104 for HA with MC-LAG configuration .  In that we have advertised the below networks in BGP and also prepend the AS path in router 2 for making it more longer

123.255.248.0/22
203.223.188.0/24
203.223.189.0/24
203.223.190.0/24
203.223.191.0/24
43.255.164.0/22
203.112.128.0/24
203.223.129.0/24
203.223.130.0/24

We found that all the inbound traffic to the above mentioned network comes through ISP-1 only, We need the inbound traffic for network 203.223.191.0/24 should come through ISP-2 . Herewith i have attached the configuration and topology diagram for your reference . Please check and help me with the scripts in configuring the same.

 

We have done the intial BGP configuration with the help of I2J conversion tool , Please help me with the script for entire BGP configuration.

 

Thanks & Regards

Maheswaran

Distinguished Expert
Posts: 2,250
Registered: ‎08-21-2009
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Re: Reg BGP inbound traffic through particular ISP

Hello,

I can see 2 options for You here:

1/ if Your ISP-1 supports communities to increase/reduce Local Preference, attach appropriate community to  203.223.191.0/24 announce towards ISP-1. You can check Your ISP-1 peering policy to find out what communities are supported. Example being:

https://us.ntt.net/support/policy/routing.cfm#communities

 

2914:450	96	customer fallback

So, if Your ISP-1 is NTT, then attaching community 2914:450 to Your announce will cause LP reduce inside NTT network, and NTT will use other ISPs to get to Your 203.223.191.0/24 prefix.

2/ aggregate  203.223.190.0/24 and  203.223.191.0/24 into  203.223.190.0/23. Announce 203.223.190.0/23 to ISP-1 and both /24 to ISP-2.

HTH

Thx

Alex

_____________________________________________________________________

Please ask Your Juniper account team about Juniper Professional Services offerings.
Juniper PS can design, test & build the network/part of the network as per Your requirements

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Distinguished Expert
Posts: 575
Registered: ‎08-15-2012
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Re: Reg BGP inbound traffic through particular ISP

Hi,

 

I believe altering AS-PATH pre-pend for 203.223.191.0/24 could also achieve this:
ISP-1: as-path prepend 202.223.191.0/24 on both routers

ISP-2: Normal BGP announcement for 202.223.191.0/24 on both routers

 

Cheers,

Ashvin

Distinguished Expert
Posts: 2,250
Registered: ‎08-21-2009
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Re: Reg BGP inbound traffic through particular ISP

Hello,


AshvinO wrote:

Hi,

 

I believe altering AS-PATH pre-pend for 203.223.191.0/24 could also achieve this


Not always - i.e. may not work for traffic coming from within ISP-1 itself.

For instance, if You read the NTT peering policy, they give customers LP==120 by default - it means AS_PATH prepending won't work for traffic coming from other NTT customers UNLESS ISP-2 is also NTT!

Deaggregation is the only reliable way barring LP decrease by way of community.

HTH

Thx

Alex

_____________________________________________________________________

Please ask Your Juniper account team about Juniper Professional Services offerings.
Juniper PS can design, test & build the network/part of the network as per Your requirements

+++++++++++++++++++++++++++++++++++++++++++++

Accept as Solution = cool !
Accept as Solution+Kudo = You are a Star !