BGP Distance

[Shaqxify]

Hello Esteemed Tech Fam,

I have this scenario, 2 Vendors (ISPs), one router with both vendors running BGP.

V1=AS 65284

V2=AS 200

Question

How do I make AS 65284 as the primary and AS 200 the secondary. Below is the current configuration in place.

router bgp 65530
bgp log-neighbor-changes
neighbor 172.16.1.29 remote-as 65284
neighbor 172.16.1.29 update-source FastEthernet0/1
neighbor 172.25.1.33 remote-as 200
neighbor 172.25.1.33 update-source FastEthernet0/0/1
!
address-family ipv4
no synchronization
network 10.207.100.0 mask 255.255.255.0
network 10.207.101.0 mask 255.255.255.0
network 10.207.102.0 mask 255.255.255.0
network 10.207.103.0 mask 255.255.255.0
network 10.207.104.0 mask 255.255.255.0
network 10.207.106.0 mask 255.255.255.0
network 128.11.0.0 mask 255.255.255.0
neighbor 172.16.1.29 activate
neighbor 172.16.1.29 soft-reconfiguration inbound
neighbor 172.25.1.33 activate
neighbor 172.25.1.33 soft-reconfiguration inbound
no auto-summary
exit-address-family

Regards

Shaqx

[balaji.bandi]

You looking also if ISP 1 Failed you looking to Fail over ISP 2 ?  ( the network IP address mentioned provided by ISP ?)

you need to use Route-Map with BGP attrubutes.

example :

https://www.youtube.com/watch?v=Me85086UhtY

Additional some help on the config :

https://networkphil.com/2017/05/30/dual-wan-router-with-dual-isp-using-bgp-and-ospf/

[Shaqxify]

Hello Balaji,

Thank you for the pointers, I have gone through what you have shared and came up with below.

Router bgp 65530
neighbour 172.16.1.29 remote-as 65284
neighbour 172.16.1.29 route-map FILTER in
neighbour 172.25.1.33 remote-as 200
neighbour 172.25.1.33 route-map FILTER in

route-map FILTER permit 10
match ip address prefix-list default-only
match as-path 10
set local-preference 150

route-map FILTER permit 20
match ip address prefix-list default-only

ip as-path access-list 10 permit 65530
ip prefix-list default-only permit 0.0.0.0/0

Please let me know if this will work.

Salute'

Shaqx

[Seb Rupik]

Hi there,

To ensure symmetric routing you should create a routing policy inbound traffic. Since you only have a single router I've opted to use the weight attribute for affecting outbound path selection. As you are multihomed to two different AS, AS_PATH prepending is used to influence inbound path selection upstream of your AS:

!
router bgp 65530
 neighbor 172.16.1.29 remote-as 65284
 neighbor 172.16.1.29 route-map SETLOCAL in
 neighbor 172.25.1.33 remote-as 200
 neighbor 172.25.1.33 route-map AS-PREPEND out
!
route-map SETLOCAL permit 10
  set weight 100
!
route-map AS-PREPEND permit 10
 set as-path prepend 2
!

cheers,

Seb.

[Shaqxify]

Thank You So Much Seb, I Will Be Deploying This In Few Hours And Will Revert With The Outcome.

[Shaqxify]

Hi Seb,

Traffic is preferring the AS 200 after the configuring the route maps, it would have more preferable if traffic was on AS 65284.

Regards,

Shaqx

[Seb Rupik]

Can you share the output of sh ip bgp ?

[Shaqxify]

Please do find attached.

Regards,

Shax

[Seb Rupik]

AS200 is the pregrerred egress AS for the following prefixes:

*> 10.207.90.0/24   172.25.1.33                            0 200 200 i
*> 10.207.91.0/24   172.25.1.33                            0 200 200 i
*> 10.207.92.0/24   172.25.1.33                            0 200 200 i
*> 10.207.93.0/24   172.25.1.33                            0 200 200 i
*> 10.207.94.0/24   172.25.1.33                            0 200 200 i
*> 10.207.95.0/24   172.25.1.33                            0 200 200 i
*> 10.207.96.0/24   172.25.1.33                            0 200 200 i
*> 41.215.142.120/30 172.25.1.33                            0 200 ?
*> 128.6.0.0/24     172.25.1.33                            0 200 200 i
*> 172.25.1.0/30    172.25.1.33                            0 200 ?
*> 172.25.1.8/30    172.25.1.33                            0 200 ?
*> 172.25.1.12/30   172.25.1.33                            0 200 ?
r> 172.25.1.32/30   172.25.1.33                            0 200 ?
*> 192.168.30.140/30  172.25.1.33                            0 200 ?

...but that is only because those prefixes are not being advertised via AS65284. If you wanted to go via AS65284 you would need to filter those prefixes from the AS200 updates, your traffic would then follow the default route via AS65284.

cheers,

Seb.