Note_Tech

All technological notes.

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AWS Networking - Transit Gateway

transit_gateway_topologies

Transit Gateway
- Used to establish transitive peering between thousands of VPC and on-premises, hub-and-spoke (star) connection
Features:
- Regional resource, can work cross-region
- You can peer Transit Gateways across regions
- Share (VPC sharing) cross-account using Resource Access Manager (RAM)
- Works with Direct Connect Gateway, VPN connections
- the only AWS service supports IP Multicast
  - not supported by any other AWS service
need to setup Route Tables:
- limit which VPC can talk with other VPC

transit_gateway_diagram

To increase the bandwith of site-to-site VPN connection
ECMP:
- Equal-cost multi-path routing
- Routing strategy to allow to forward a packet over multiple best path
Use case:
- create multiple Siteto-Site VPN connections to increase the bandwidth of your connection to AWS

transit_gateway_ecmp

When establish a vpn, there are actually 2 tunnels, one going forward and one going back.
When using transit gateway, and can have multiple VPN and two tunnels per VPN can be used at a time.
- In the above case, there are 2 VPN attachments with 4 tunnels, increase the throughput of the connection.
Throughput with VPN

transit_gateway_ecmp_throughput01

transit_gateway_ecmp_throughput02

Sample:
- You want to scale up an AWS Site-to-Site VPN connection throughput, established between your on-premises data and AWS Cloud, beyond a single IPsec tunnel’s maximum limit of 1.25 Gbps. What should you do?
  - Transit Gateway

transit_gateway_multiple accounts