Wan Priorization BGP

[arnaud.ravazzola1]

Good morning,

I have a problem with the configuration of BGP. I enclose with this message, the diagram of the network.

I have 4 AS with 4 routers cisco. Between Router3 and Router4, 9 ways (3x3) are possible.

I want to prioritize the red path then if it is not avaible, the link called Wan1 and finally if neither the red link nor the link called Wan1 are avaible, used the link called Wan2.

I know the weight attribute but i think it's not the right way. Can we prioritize with the interface rather a weight on the neighbor ?

I hope I was clear.

Thank you for your time.

Best regards,

Arnaud Ravazzola

[Julio E. Moisa]

You are welcome,

If you need any assistance we will be here.

Have a great day.

:-)

[paul driver]

Hello

@julio

Relating to this topology why would you use LP .when weight is more of a better PA value and neither is advertised to an ebgp peer?

res

paul

[Julio E. Moisa]

Hi Paul,

No doubts, for this specific topology Weight and Local-Preference could be used and they will complete the objective, now what about if the topology growth and new iBGP routers are included into the AS300, from my point of view Local-preference is most manageable than weight, because Weight is locally significant, but everything depends of the network plans and how it should be implemented in a future.

[paul driver]

Hello

Arh now I understand your suggestion of LP for the egress traffic, it was for future growth, and not solely based on the OP and its current topology,- However given the current topology,, which is a single rtr in each client ASN peering with multiple links to the same upstream provider, I would go for.

Egress - weight
Ingress - AS-path  <------- Would like the return traffic to use the same link otherwise you may obtain asymmetric routing

route-map As-path-wan2
set as-path prepend 300 300

route-map As-path-wan3
set as-path prepend 300 300 300

router bgp 300
neigbour (WAN1) weight 60000
neigbour (WAN2) weight 50000
neigbour (WAN2) route-map As-path-wan2  out
neigbour (WAN3) route-map As-path-wan3 out 

Cheers for clarification anyway Julio, very much appreciated

res
Paul

[Julio E. Moisa]

Hi Paul,

That is correct, totally agree with you, actually I suggested that below in order to avoid asymmetric.

Have a great weekend Paul.

:-) 

[arnaud.ravazzola1]

Good Morning,

Thank you very much. I have more details than skills :|

I'll develop my knowledge on route-map. I need to understand why you put a name and a number before and after the "permit". And the configuration of Paul Driver on his last comment.

Thank you for your sharing.

Arnaud

[Julio E. Moisa]

Hi,

Basically the route-maps work with sequence, and they are read from top to bottom, usually but it is not mandatory I choose multiple of 5 but you can start with the sequence 1, now name and number is a example only. You can set up any name what represents or recognize the use of the route-map.

[arnaud.ravazzola1]

I thank you again Julio Moisa.

[Julio E. Moisa]

It was a pleasure

Have a great week.

:-)