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BGP Regex to match region/location/country Networks

NDP
Beginner
Beginner

We have Dual homed topology. one ISP internet link is connected to one ASR and another ISP internet link is connected to another ASR.

 

We are looking at all options to load share the internet links - ASRs will be configured to install all internet routes not just default route.

 

We would like to see if We can prefer ISP connected to ASR1 for all EMEA IP CIDR ranges and ASR2 for AMER region IP CIDRs.

 

could someone advise if Internet -Network prefixes contain standard community values when they are originated from one particular region in the globe. for ex:- advertisements originated in AMER region to contain XYZ:1234 community value.

So, We can match this community on ASR2 to increase LP so ASR1 also sends traffic for AMER destinations through ASR2

 

in short, if We have BGP regex  to match routes originated from regions(AMER, EMEA , APAC, etc), please help me .

Thank you in advance

4 REPLIES 4

balaji.bandi
VIP Guru VIP Guru
VIP Guru

yes as long as you getting all Routes from your Provider not Default route, you can do your TE - Traffic engineering, how you want.

 

please refer below guide : just to understand how you can do the task

 

https://www.cisco.com/c/en/us/support/docs/ip/border-gateway-protocol-bgp/13753-25.html

 

Once you understand the TE - then make a Small diagram with ISP and your Router and your network, mark your self which route to take place.

 

to test use 1 subnet do not have traffic and start playing with that, so you will understand the traffic flow before you deploy other networks.

 

BB

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MHM Cisco World
Advisor
Advisor

I don't full understand how you want to load balance

BUT
there is something called SoO used to identify the origin.

you can use route-map match it and then change LP as you want.

if you can please clear are same prefix learn from both ISP?

Two ASRs will have all available internet prefixes .

 

For ex :- x.y.z.0/24 advertised by one customer /vendor in AMER region to internet. Two ASRs received the route and installed it the route table . 

 

ASR1 will advertise x.y.z.0/24 to ASR2 over ibgp link with higher LP. So, all traffic from ASR2 to x.y.z.0/24 to traverse through ASR1.

 

Another a.b.c.0/24 may be advertised by someone in Europe to internet.

Two ASRs at my organization install this into route table.

However, ASR2 advertises this received route to ASR1 with higher LP value so Traffic from ASR1 to a.b.c.0/24 should be sent to ASR2.

 

In this way, traffic to any public IP CIDR of AMER region should exit through ASR1 and Europe region subnet through ASR2 .  This way, we wanted to perform load share. 

 

To match origin/location of CIDR s, do we have any BGP community regex . Thank you in advance

 

use SoO in costumer side and match in in HQ DC and modify LP.

 

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