I am setting up IPSec VPN with BGP between AWS and GCP.
On the AWS side, I am using TGW.
It is a HA VPN with two Site-to-Site-VPN on AWS side.
There 4 tunnels in total. As confirmed from both the AWS side and the GCP side,
all the 4 tunnels are "UP" and BGP is working in all 4 of them.
When I previously used Virtual-Private-Gateway
on the AWS side to set up 4x HA IPSec VPN Tunnels to GCP, the route tables on
both sides were automatically populated. (On the AWS side, I had enabled Route-Propagation
on the route table). On the GCP side, after the tunnels were established, two dynamic routes were automatically added; the destination was AWS VPC CIDR and the next hop was the two tunnels' GCP side inner address.
However, now that I am using TGW instead of VGW on the AWS side, no routes are automatically added even after all the four tunnels are "up" and BGP is working. On the AWS side, I added a
static route to the subnet's routing table. I added a TGW routing table and added a static route
to that. In both the static route, the destination is the GCP VPC CIDR and the next hop is the
TGW and TGW-Attachment respectively. However, on the GCP side, I am not
able to add a static route in the VPC's route table. What could be missing to set up the routing on the GCP side?
