How BGP TE can use to send internal prefix traffic via one ISP LK

[bandararmc]

Hi all, 

We have few ISP providers and few public subnets. we need send/receive one specific prefix traffic via one ISP provider for any destination.

For Inbound traffic, I can use AS-PATH prepend option. 

But I have a concern how to control outbound traffic from our AS for any destination. As per my knowledge we can use Local Preference as a inbound policy on the BGP peer to control outbound traffic but you may need to know destination IPs. 

Here I only know the internal prefix, so I used below config using

ip access list extended

but that did not help and when I checked BGP Routing, there was no change on LP values. Any good suggestion to solve this scenario please? 

************************

Used config 

ip access-list extended ABCDE
permit ip any aa.bb.cc.0 0.0.0.255
!
!
route-map XVZ permit 10
match ip address ABCDE
set local-preference 200
!
route-map XVZ permit 20

router bgp xxxx
address-family ipv4
neighbor aa.bb.cc.dd route-map XYZ in

***************************

Thank you in advance... 

[Kanan Huseynli · Accepted solution]

Hi,

what is

prefix-list

you try to match and set LP to 200? If it is local prefix, then obviously it will not work. And since destination is any and you want to route from specific your subnet (prefix) via selected ISP, you can't do such control with BGP. Use policy-based routing.

[MHM Cisco World]

if you have dual ISP then you can control Outbound via LP.
this make router prefer routes via one ISP 
I dont see wrong in your config 

[Kanan Huseynli]

Hi,

based on requirement, author needs to send to specific ISP based on local prefix. Route control with LP is for destination prefixes.

[MHM Cisco World]

he have dual ISP 
he can set LP without need to match any prefix 
what he need is 
neighbor x.x.x.x route-map LP in 
!
route-map LP permit 10
set LP 200

that it 
it work without need of PBR.

[bandararmc]

Hi MHM Cisco World, 

Thank you for response. 

Here what I want to set only one prefix outbound traffic via one ISP link. Not all traffic. Otherwise I will affect to our traffic balancing. 

Best Regards~~~

[MHM Cisco World]

Just one min.

You receive this destination prefix from both or one ISP?

You mention I check bgp table what excatly you check?

[bandararmc]

Hi,

There is no specific destination. So destination prefixes can be received from any ISP link. 

Best Regards~~~

[MHM Cisco World]

so you receive default route via BGP from ISP ??
if that case then sure you can not use LP 
you can use PBR as @Kanan Huseynli  mention above. 
if you receive this public IP from ISP you can use LP or you can use LP to shift all traffic via one ISP.

[Kanan Huseynli]

With your configuration it affects all routing. He needs only from specific source prefix, read requirements please.

[paul.driver]

Hello
Just like to add It seems it’s been assumed by the OP stating local preference that the isp connections are via multiple wan rtrs it doesn’t state this, So if they are attached via a single wan rtr, then the weight preference would be applicable for egress routing.

[paul driver]

Hello
Just like to add It seems it’s been assumed by the OP stating local preference that the isp connections are via multiple wan rtrs it doesn’t state this, So if they are attached via a single wan rtr, then the weight preference would be applicable for egress routing.