Troubleshooting AWS RAM Shared Subnets Communication Issue

DevOps AWS
#1

Hello guys, I am a DevOps Engineer freelancing currently having 6.5 years of experience and I am stuck at a point for which neither there is any documentation available on the internet, nor anyone has tried this scenario
I have 3 accounts A, B and C

  1. A has vpc and private and public subnets, route tables, nat gateway and internet gateway
  2. B has vpc and private and public subnets, route tables, nat gateway and internet gateway
  3. Now I shared the subnets of B to C using AWS RAM (so basically, B and C both in same subnet range [10.129.0.0/16])
  4. Now I create transit gateway in A and share that to B using AWS RAM
  5. Then I add the routes and VPC TGW attachments and complete that guide on the internet with 2 accounts able to communicate with each other
  6. Now since I shared subnets of B to C, so when I test via reachability analyzer on B to check connectivity from C instance to A, it says reachable
  7. If I go to account C and do the same reachability analyzer to check connectivity to A, it fails on the route table of B (shared during subnet share in RAM also visible on C).
#2

Does vpc flow logs in A show the traffic making it from C instances in the B subnet?

#3

Actually, the thing is I used vpc reachability analyzer in account B to test if instance running in C is able to communicate with any of the resource of A, and yes it was successful.
But when I run the same reachability analyzer in account C to test if instance of C can communicate with A, it fails

#4

Hi I have successfully resolved it. It was the issue with reachability analyzer since trust access wasn’t enabled and I read the documentation which said for cross accounts analyzing trust access is needed.
When I ssh’d into instance from there I started telnet and all, finally it worked