BGP load balancing active on two links

[Fabio]

Hello guys,

I have a cluster of Fortigate connected with another couple of FGT with two links in protocol BGP.

I have choose to set one primary and one in backup with the weight.

I would like now share the links in active way mode, to load balacing both of them in upload than in download, so in routing table have for each remote network both the links with the same distance and metric.

This is my conf:

Thanos_GRA (BGP_DR) # sh router bgp
config router bgp
set as 65000
set router-id 2.1.71.238
config neighbor
edit "2.1.71.237"
set description "Gravina_vs_Siziano_1"
set remote-as 1267
set keep-alive-timer 45
set holdtime-timer 120
set connect-timer 60
set weight 200
next
edit "2.1.71.245"
set description "Flaminia_vs_Siziano_2"
set remote-as 1267
set keep-alive-timer 45
set holdtime-timer 120
set connect-timer 60
set weight 90
next
end

Thanos_GRA (BGP_DR) # get router info bgp network 192.168.202.0
VRF 0 BGP routing table entry for 192.168.202.0/24
Paths: (2 available, best #1, table Default-IP-Routing-Table)
Advertised to non peer-group peers:
2.1.71.245
Original VRF 0
1267 1267
2.1.71.237 from 2.1.71.237 (151.7.203.107)
Origin IGP metric 0, localpref 100, weight 200, valid, external, best
Extended Community: RT:1267:64921
Last update: Wed Apr 6 12:04:07 2022

Original VRF 0
1267 1267 1267
2.1.71.245 from 2.1.71.245 (151.7.203.107)
Origin IGP metric 0, localpref 100, weight 90, valid, external
Extended Community: RT:1267:64921
Last update: Fri Mar 25 23:17:53 2022

Thanos_GRA (BGP_DR) # get router info routing-table details 192.168.202.0/24

Routing table for VRF=0
Routing entry for 192.168.202.0/24
Known via "bgp", distance 20, metric 0, best
Last update 01w1d23h ago
* 2.1.71.237, via VLAN_71 distance 0

If I set the weight at the same value, could i achieve the goal?

Thank you for the answer.

Fabio

[Fabio]

Hi Adrian,

you tell me 2.1.71.245 neighbor. Maybe the other 2.1.71.237 ?

To  equalize the paths? three and three?

[akristof · Accepted solution]

Oh, my bad. I took wrong neighbor when I copied it. Yes, I meant 2.1.71.237 :)

[Fabio]

GOOD, PERFECT Adrian !

Thanos_GRA (Siziano_DR) # get router info routing-table details 192.168.224.0/23

Routing table for VRF=0
Routing entry for 192.168.224.0/23
Known via "bgp", distance 20, metric 0, best
Last update 00:01:38 ago
* 2.1.71.237, via VLAN_71 distance 0
* 2.1.71.245, via VLAN_72 distance 0

This is in routing table, although in the BGP there is always one BEST .. It's normal condition ?

[akristof]

Hello,

Yes. Because BGP will always select one route as best, but if you have multipath enabled, it will forward same networks with same parameters to kernel.

Glad that I've helped.

[Fabio]

yes i enabled before multipath :

config router bgp
set as 65000
set router-id 2.1.71.238
set ebgp-multipath enable
set ibgp-multipath enable
config neighbor
edit "2.1.71.237"
set description "Gravina_vs_Siziano_1"
set remote-as 1267
set route-map-in "AS_PREPEND"
set keep-alive-timer 45
set holdtime-timer 120
set connect-timer 60
set weight 200
next
edit "2.1.71.245"
set description "Flaminia_vs_Siziano_2"
set remote-as 1267
set keep-alive-timer 45
set holdtime-timer 120
set connect-timer 60
set weight 200
next
end

thank you so much Adrian

[Fabio]

i see the different lenght path of as-path:

Original VRF 0
1267 1267 1267
2.1.71.245 from 2.1.71.245 (151.7.203.107)

and the second ...the best 'cause much short

Original VRF 0
1267 1267
2.1.71.237 from 2.1.71.237 (151.7.203.107)

how could change the lenght of as-path ? with route-map ? and the form ?

thank you