How does Dx-connect gateway does path preference

Question

Hi All,

I need your help in understanding the path selection algorithm associated with DX-connect gateway.
I have a DX-connect gateway connect with my on-premises environment using 4 DX-connects links from different DX-connect location with different latencies.

I want my 1st link to be primary 2nd to be secondary and so on, to do so I am doing AS-Path prepending from onPrem routes for the prefix advertisement towards DX-connect link, but looks like it is not effective and AWS is still doing multipathing.
So wanted to know
1) is there anyway to see the prefixes being received from OnPrem router in the DX-connect?
2) How does path selection work at DX-connect?
3) Can I manipulate path selection from AWS side as well or it just the onPrem router to do everything for inbound and outbound both?

Please help to understand this.

Thanks,

Answer

Suggest checking this [Knowledge Center article](https://aws.amazon.com/premiumsupport/knowledge-center/direct-connect-private-transit-interface/); also, have you tried using BGP communities as mentioned in the [documentation](https://docs.aws.amazon.com/directconnect/latest/UserGuide/routing-and-bgp.html#bgp-communities-private-transit)?

Answers to your questions:

**Q.** is there anyway to see the prefixes being received from OnPrem router in the DX-connect?

**A.**  Suggest opening a support case, this information can be checked by the support only

**Q.** How does path selection work at DX-connect?

**A.** See the article I shared

**Q.** Can I manipulate path selection from AWS side as well or it just the onPrem router to do everything for inbound and outbound both?

**A.** Both inbound and outbound route manipulation must be done at the on-premises routers

Also check this [blog](https://aws.amazon.com/blogs/networking-and-content-delivery/creating-active-passive-bgp-connections-over-aws-direct-connect/) which explains the routing in detail

How does Dx-connect gateway does path preference

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