Using AS-Path attribute to influence routing over multiple regions

0

We have standard approach to influence routing using AS-Path. I could see we are unable to do on AWS and when we have connection homed in different regions. Is there a way we can use AS-Path to influence traffic instead of any other best path selection algorithm?

Imran
demandé il y a 7 mois360 vues
4 réponses
0
Réponse acceptée

From AWS Doc: When you have multiple virtual interfaces in the same associated Region, you can set the AS_PATH attribute to prioritize which interface AWS uses to route traffic. However, AS_PATH prepending doesn’t work when the Direct Connect connections are in different associated AWS Regions than the VPC. https://docs.aws.amazon.com/directconnect/latest/UserGuide/routing-and-bgp.html#private-routing-policies

However you can use AS-Path as your primary best path selection algorithm firstly by setting equal preference with Local preference BGP communities values e.g. (7200:100) on all the connections(VIFs). Which leads to tie in path selection hence AS-Path can be evaluated as a tie breaker. By also advertising your prefixes with different AS-Path length will influence traffic flow from AWS based on AS-Path.

AWS
répondu il y a 7 mois
profile picture
EXPERT
vérifié il y a 2 mois
0

Hi khanakee, So if I correctly understood this is that if I set the same BGP local preference community across all the VIFs, then I can use AS-Path to influence how routing takes place from AWS side. Is that correct?

Imran
répondu il y a 7 mois
  • Hello Imran, yes that is correct

0

The best practice from AWS when it comes to multi-region traffic engineering is to use communities. This article goes into the same scenario you described https://repost.aws/knowledge-center/direct-connect-bgp-communities also look at https://docs.aws.amazon.com/directconnect/latest/UserGuide/routing-and-bgp.html#local-pref-bgp-communities

AWS
TonyG
répondu il y a 7 mois
profile picture
EXPERT
vérifié il y a 2 mois
0

On the multi region with direct connect usage u need to use :

  • Local preference ,
  • bgp communities to influence routing
répondu il y a 5 mois

Vous n'êtes pas connecté. Se connecter pour publier une réponse.

Une bonne réponse répond clairement à la question, contient des commentaires constructifs et encourage le développement professionnel de la personne qui pose la question.

Instructions pour répondre aux questions