Load Sharing using iBGP

[Dipesh Patel]

Dear Experts,

We need to implemet iBGP Load Sharing between two MPLS Service Provider -TATA and Airtel.

The Details of AS no's are mentioned in the diagram attached.

Kindly help how to configure 2 CE routers of SP and L3 switch. We do not wantto use any IGP between all these three devices.

Diagram :

Regards,

[Konstantin Dunaev]

RIB failure just mean that the prexif is via IGP available.

the poblem is - you try to set local-preference on wrong router and wrong direction: you should apply on TATA and AIRTEL  router the route-map as incoming.  Because you change specific attributes on INCOMING BGP information in order to route the OUGOING traffic.

[Dipesh Patel]

Dear Konstantin,

I do not understand the incoming and outgoing direction. Litle bit confused. Could you explain please?

I had tried by applying this Route-map (by changin it to the remote traffic) on TATA and Airtel CE Router for traffic comming to CORE switch from remote location but there is no effect.

I had also tried the applying this route-map (local traffic) going outside from TATA and AIRTEL router but there is no effect.

Could you please give the configuration script specific for one location according to my scenario than it will a great helf for me.

Regards,

[Konstantin Dunaev · Accepted solution]

Hi Dipesh,

you should undestand the followin: BGP defines how the traffic will be routed ingress and outgress of you network.

The BGP information that you're sending TO your ISP defines how the incoming traffic will be routed to your network.

The BGP information that you're gettin FROM your ISP defines how the outgoing traffic will be routed from you network.

it should  look like this:

TATA CE router :

router bgp 65500

bgp log-neighbor-changes

neighbor 172.1.25.189 remote-as 4755

!

address-family ipv4

  neighbor 172.1.25.189 activate

  neighbor 172.1.25.189 allowas-in

  neighbor 172.1.25.189  route-map TATA-IN in

route-map TATA-IN permit 10

match ip address 1

set local-preference 150

route-map TATA-IN permit 20

match ip address 2

set local-preference 50

Airtel CE router :

router bgp 65500

bgp log-neighbor-changes

neighbor 22.1.25.189 remote-as 7777

!

address-family ipv4

neighbor 22.1.25.189 activate

neighbor 22.1.25.189 allowas-in

neighbor 22.1.25.189 route-map AIRTEL-IN in

route-map AIRTEL-IN  permit 10

match ip address 1

set local-preference 50

route-map AIRTEL-IN permit 20

match ip address 2

set local-preference 150

[Dipesh Patel]

Dear Komstentin,

Thanks, It's working now. but I have to idetify each subnets manually.

Is there any way to select the traffic automatically without manual intervention?

Regards,

[Konstantin Dunaev]

Hi Dipesh,

I'm glad to hear that it works.

To the subnets, I don't know how to do it automaticaly, as I said we used Netflow just to estimate the traffic volume and split all networks into 2 parts, but we used somethink like that:

ip prefix-list to_Telia description What to send to Telia .

ip prefix-list to_Telia seq 5 deny 0.0.0.0/0

ip prefix-list to_Telia seq 10 deny 127.0.0.0/8 le 32

ip prefix-list to_Telia seq 15 deny 192.168.0.0/16 le 32

ip prefix-list to_Telia seq 20 deny 10.0.0.0/8 le 32

ip prefix-list to_Telia seq 25 deny 172.16.0.0/12 le 32

ip prefix-list to_Telia seq 30 permit 84.64.0.0/10 le 32

ip prefix-list to_Telia seq 35 permit 84.128.0.0/9 le 32

ip prefix-list to_Telia seq 40 permit 85.0.0.0/8 le 32

ip prefix-list to_Telia seq 45 permit 86.0.0.0/7 le 32

ip prefix-list to_Telia seq 50 permit 88.0.0.0/5 le 32

ip prefix-list to_Telia seq 55 permit 96.0.0.0/3 le 32

ip prefix-list to_Telia seq 60 permit 128.0.0.0/1 le 32

!

ip prefix-list to_Telia1 description What to send to Telia1.

ip prefix-list to_Telia1 seq 10 deny 127.0.0.0/8 le 32

ip prefix-list to_Telia1 seq 15 deny 192.168.0.0/16 le 32

ip prefix-list to_Telia1 seq 20 deny 10.0.0.0/8 le 32

ip prefix-list to_Telia1 seq 25 deny 172.16.0.0/12 le 32

ip prefix-list to_Telia1 seq 30 permit 0.0.0.0/2 le 32

ip prefix-list to_Telia1 seq 35 permit 64.0.0.0/4 le 32

ip prefix-list to_Telia1 seq 40 permit 80.0.0.0/6 le 32

ip prefix-list to_Telia1 seq 45 permit 0.0.0.0/0

I mean one could write a smal shell-script which would process a Netflow data, create a new ip-prexis lists and upload it to the routers.

[Dipesh Patel]

Dear Konstentin,

I am not aware of the Shell-Script. Do you have any idea than please share. I can try. Because in my case there are 80 nos of Segment at each location. There 8 to 10 Location with two MPLS links and need to load sahre between two MPLS links.

It is very difficult to to share manually. That's why I am asking for other way to dive the traffic.

Regards,

[Konstantin Dunaev]

Hi,

no, sorry I don't have such a script, it was just a thoughts.

I understand that for so many locations the manual process is not an optimal solution, but as I said you'll need to check and update the policy may be once a half-year if you tolerate 10-20% of diference in load-sharing.