Tutorial / Cram Notes

Amazon Web Services (AWS) offers a variety of networking services that enable customers to establish connectivity between their AWS resources and on-premises infrastructure. When architecting hybrid environments, one of the key considerations is the management of routing protocols to ensure efficient and secure data flow. AWS supports several connectivity options including AWS Direct Connect and VPN connections, each with its own routing configuration aspects.

AWS Direct Connect

AWS Direct Connect allows for the establishment of dedicated network connections from your premises to AWS. This connection can reduce network costs, increase bandwidth throughput, and provide a more consistent network experience than internet-based connections.

When configuring AWS Direct Connect, routing is a critical element. It supports both static routing and BGP (Border Gateway Protocol). BGP is the preferred routing protocol as it allows for automatic route updates and provides a more resilient and scalable solution.

BGP Routing with AWS Direct Connect:

  • Dynamic Routing: With BGP, route advertisement is dynamic. It enables the automatic propagation of routes between your network and your VPCs.
  • AS Numbers: You must use Autonomous System Numbers (ASNs) to establish a BGP session. AWS assigns a private ASN for the Amazon side when you create a Direct Connect connection.
  • Multi-Protocol BGP (MP-BGP): AWS Direct Connect supports MP-BGP for VPN connections over Direct Connect virtual interfaces, which allows for the association of VGWs with Direct Connect gateways.

VPN Connections

A VPN connection allows you to securely connect your on-premises network to your AWS resources and VPCs over the internet. AWS offers both hardware and software VPN solutions.

VPN Routing Options:

  • Static Routing: With static routing, you manually specify the routes to your network in your VPC route table.
  • Dynamic Routing (BGP): Similar to AWS Direct Connect, you can configure BGP to dynamically exchange routes between your VPC and on-premises network.

Routing Protocols Comparison

Here’s a comparison of routing protocols for AWS Direct Connect and VPN connections:

Feature AWS Direct Connect VPN Connection
Protocol Options BGP, Static BGP, Static
Bandwidth Up to 100 Gbps Generally up to 1.25 Gbps
Connection Resilience Resilient with BGP Multiple tunnels for high availability
Cost Typically higher due to dedicated line Lower, pay-as-you-go pricing
Latency Lower latency compared to internet-based Latency dependent on internet
Encryption Not natively provided; must be implemented at the layer above Encrypted by default (IPSec)

BGP Configuration Example for AWS Direct Connect

Here’s a simplified example of how you would configure BGP for Direct Connect:

router bgp YOUR_ASN
neighbor AWS_DIRECT_CONNECT_IP remote-as AWS_ASN
address-family ipv4
network YOUR_LOCAL_NETWORK_CIDR
neighbor AWS_DIRECT_CONNECT_IP activate
neighbor AWS_DIRECT_CONNECT_IP route-map YOUR_ROUTE_MAP in

This configuration snippet sets up a BGP session with AWS, advertises your local network, and applies a route map for incoming routes.

VPN Configuration Example with BGP

For a VPN connection with BGP, the VPN device configuration would look like:

crypto ikev1 enable outside
crypto ikev1 policy 1
authentication pre-share
encryption aes-256
hash sha
group 5
lifetime 86400
!
tunnel-group AWS_VPN_IP type ipsec-l2l
tunnel-group AWS_VPN_IP ipsec-attributes
ikev1 pre-shared-key YOUR_PRESHARED_KEY
!
router bgp YOUR_ASN
neighbor AWS_VPN_IP remote-as AWS_ASN
address-family ipv4
network YOUR_LOCAL_NETWORK_CIDR
neighbor AWS_VPN_IP activate
!

It’s important to replace `YOUR_ASN`, `AWS_DIRECT_CONNECT_IP`, `AWS_ASN`, `YOUR_LOCAL_NETWORK_CIDR`, `YOUR_ROUTE_MAP`, `AWS_VPN_IP`, and `YOUR_PRESHARED_KEY` with your actual values for these placeholders.

Managing routing protocols for AWS and hybrid connectivity options involves understanding the capabilities and limitations of each service and choosing the configuration that matches the performance, security, and resilience needs of your application. AWS provides comprehensive documentation and guidelines to assist in setting up and managing these connections, and obtaining an AWS Certified Advanced Networking – Specialty certification will provide deeper insights and practical knowledge in this area.

Practice Test with Explanation

AWS Direct Connect allows you to establish a dedicated network connection from your premises to AWS.

  • (A) True
  • (B) False

Answer: A

Explanation: AWS Direct Connect is a cloud service solution that makes it easier to establish a dedicated network connection from your premises to AWS.

A hardware VPN connection over the internet should be considered when you require high availability.

  • (A) True
  • (B) False

Answer: B

Explanation: For high availability, AWS recommends using multiple VPN connections and Direct Connect connections, as a hardware VPN over the internet alone may not guarantee the desired level of availability.

BGP is required for dynamically managing the routes when using AWS Direct Connect.

  • (A) True
  • (B) False

Answer: A

Explanation: BGP (Border Gateway Protocol) is used for dynamically exchanging routes between your on-premises networks and your VPC over an AWS Direct Connect connection.

Which AWS service would you use to establish a secure and private virtual interface between your on-premises network and your Amazon VPC?

  • (A) Amazon Route 53
  • (B) AWS Transit Gateway
  • (C) AWS Direct Connect
  • (D) AWS Site-to-Site VPN

Answer: C

Explanation: AWS Direct Connect is used to establish a secure and private virtual interface between on-premises networks and Amazon VPCs.

AWS Transit Gateway acts as a hub that controls how traffic is routed among all the connected networks which act like spokes.

  • (A) True
  • (B) False

Answer: A

Explanation: AWS Transit Gateway serves as a hub that allows you to manage and route traffic between all your connected networks, functioning like a network-transit hub.

What is the maximum transmission unit (MTU) size for traffic over an AWS Direct Connect connection?

  • (A) 1500 bytes
  • (B) 8500 bytes
  • (C) 9001 bytes
  • (D) 4470 bytes

Answer: D

Explanation: The maximum MTU size for traffic over an AWS Direct Connect connection is 1500 bytes, but with jumbo frames enabled, it supports an MTU of 9001 bytes, not 4470 bytes. The correct and most common MTU size in many cases would be 1500 bytes for standard frames.

AWS VPN CloudHub allows multiple site-to-site VPN connections to connect with each other.

  • (A) True
  • (B) False

Answer: A

Explanation: AWS VPN CloudHub is designed for use cases where there are multiple branch offices and existing internet connections, allowing these sites to connect with each other over site-to-site VPN connections.

AWS Direct Connect supports IPv6 for all its connections.

  • (A) True
  • (B) False

Answer: A

Explanation: AWS Direct Connect does support IPv6 in addition to IPv4 for all its connections.

What feature can you use to ensure data transfer redundancy when configuring a VPN connection to your VPC?

  • (A) Redundant gateways
  • (B) BGP multihop
  • (C) VGW (Virtual Private Gateway) dual-tunnel
  • (D) AWS Shield

Answer: C

Explanation: VGW (Virtual Private Gateway) dual-tunnel provides redundancy for VPN connectivity. When you create a VPN connection, AWS provides two redundant IPsec tunnels for increased availability.

AWS Site-to-Site VPN connections enable you to replace Direct Connect entirely if you want a dedicated connection to AWS.

  • (A) True
  • (B) False

Answer: B

Explanation: AWS Site-to-Site VPN connections do not replace Direct Connect for dedicated connectivity; VPN connections are over the internet and can vary in performance, while Direct Connect provides a consistent, high-bandwidth, low-latency connection.

AWS Client VPN is an Elastic VPN service that automatically scales up or down depending on the number of connected clients.

  • (A) True
  • (B) False

Answer: A

Explanation: AWS Client VPN is a managed elastic VPN service that automatically scales the number of client connections based on user demand.

Which hybrid connectivity option provides the lowest latency connection to AWS?

  • (A) AWS Direct Connect
  • (B) AWS Site-to-Site VPN
  • (C) AWS Transit Gateway
  • (D) AWS VPN CloudHub

Answer: A

Explanation: AWS Direct Connect provides a private, dedicated connection that can offer lower latency and more consistent network performance compared to internet-based connections.

Interview Questions

What are the primary AWS services that are used to establish a hybrid network architecture with your own data centers?

The primary AWS services used to establish a hybrid network architecture are AWS Direct Connect (DX) and AWS Virtual Private Network (VPN). AWS Direct Connect establishes a dedicated network connection between your premises and AWS, providing lower latencies and potentially reduced costs over internet-based connections. AWS VPN allows you to establish a secure and private tunnel from your network or device to the AWS global network.

Can you explain the difference between AWS Direct Connect’s private VIF and public VIF?

A private Virtual Interface (VIF) is used to access resources that are in your Virtual Private Cloud (VPC), such as EC2 instances or RDS databases. It uses private IP addresses and keeps traffic within the AWS backbone. A public VIF is used to access public AWS services outside of your VPC, like S3 or DynamoDB, that are reachable within the AWS global network. The public VIF allows direct access using public IP addresses but does not route internet-bound traffic.

How do BGP attributes influence routing decisions in a hybrid network environment using AWS?

BGP attributes such as AS Path, Local Preference, MED (Multi-Exit Discriminator), Weight (a Cisco-specific attribute), and Origin influence routing decisions. In a hybrid network, these attributes determine the most favorable path for data to travel from the data center to AWS. For example, Local Preference can be used to prefer one path over another. In AWS, the BGP community tags can also contribute to route preference and decision-making.

What AWS service can be used to resolve DNS queries from on-premises systems in AWS VPCs without exposing this traffic to the internet?

AWS Route 53 Resolver can be used to resolve DNS queries from on-premises systems in AWS VPCs without the need to send DNS queries over the internet. Route 53 Resolver provides both DNS forwarding, for routing DNS queries from AWS to on-premises DNS servers, and inbound endpoint functionality that allows on-premises systems to resolve AWS VPC DNS names.

What is the difference between AWS Transit Gateway and AWS VPN CloudHub?

AWS Transit Gateway acts as a cloud router that simplifies network architecture by allowing transitive connectivity between VPCs and on-premises networks. It eliminates the need to implement multiple VPC peering connections by serving as a central hub. AWS VPN CloudHub, on the other hand, is a feature of AWS Site-to-Site VPN that provides a hub-and-spoke model for connecting multiple branch offices or remote sites using a secure VPN setup.

How can you leverage AWS Direct Connect Gateway to connect multiple VPCs to your on-premises network?

AWS Direct Connect Gateway allows you to connect to multiple VPCs in the same or different AWS Regions using a single AWS Direct Connect connection. By attaching your Direct Connect connection to a Direct Connect Gateway, and then associating the gateway with multiple VPCs, you can route traffic to and from these VPCs using your on-premises network connection.

In what scenarios would you recommend setting up a Software VPN over a hardware VPN on AWS?

A software VPN is recommended in scenarios where flexibility and rapid deployment are more critical than the high throughput and low latency that hardware VPNs offer. It is also preferred when there are specific cryptographic requirements or custom configurations needed that AWS VPN does not support natively.

How does AWS Direct Connect bypass the public internet and what implications does this have for data transfer?

AWS Direct Connect bypasses the public internet by establishing a direct, private connection between an AWS Direct Connect location and your data center, office, or colocation environment. This reduces the exposure to internet-based threats, often results in more stable and reliable network performance, and can lead to reduced bandwidth costs for high-volume data transfer.

What is VPN Failover and how can it be configured on AWS?

VPN Failover is a mechanism for maintaining network connectivity by automatically switching to a backup VPN connection in case the primary connection fails. On AWS, VPN failover can be configured by setting up multiple VPN connections and leveraging the automatic route propagation feature in your VPC route table. AWS Site-to-Site VPN connections automatically support failover with two tunnels for redundancy.

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Katiane da Paz
6 months ago

Great blog post on managing routing protocols for AWS and hybrid connectivity! I found it very informative.

Enrique Ortega
6 months ago

Thanks! This post really helped clarify how to set up VPNs with AWS.

Cuno Hus
6 months ago

Does anyone have experience using BGP with AWS Direct Connect?

Isaac Fleury
6 months ago

Very useful post, thank you!

María José Valladares

Can anyone explain the benefits of using AWS Transit Gateway for managing hybrid connectivity?

Alison Rodriguez
6 months ago

I appreciate the detailed explanation on VPC Peering vs. Transit Gateway.

Emilia Gallardo
6 months ago

The post is great but could have included more examples of route propagation.

Rufino Almeida
6 months ago

Why would one use VPN over Direct Connect?

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