AWS Network Connectivity Options

VPC

More details @ Virtual Private Cloud

Internet Gateway

  • An Internet Gateway provides Internet connectivity to VPC
  • Internet gateway is a horizontally scaled, redundant, and highly available VPC component that allows communication between instances in your VPC and the internet.
  • Internet Gateway imposes no availability risks or bandwidth constraints on your network traffic.
  • An Internet gateway serves two purposes: to provide a target in the VPC route tables for internet-routable traffic, and to perform network address translation (NAT) for instances that have not been assigned public IPv4 addresses.
  • An internet gateway supports IPv4 and IPv6 traffic.

NAT Gateway

  • NAT Gateway enables instances in a private subnet to connect to the internet (for example, for software updates) or other AWS services, but prevent the internet from initiating connections with the instances.
  • A NAT gateway forwards traffic from the instances in the private subnet to the internet or other AWS services, and then sends the response back to the instances.
  • When traffic goes to the internet, the source IPv4 address is replaced with the NAT device’s address and similarly, when the response traffic goes to those instances, the NAT device translates the address back to those instances’ private IPv4 addresses.

Egress Only Internet Gateway

  • NAT devices are not supported for IPv6 traffic, use an Egress-only Internet gateway instead
  • Egress-only Internet gateway is a horizontally scaled, redundant, and highly available VPC component that allows outbound communication over IPv6 from instances in the VPC to the Internet, and prevents the Internet from initiating an IPv6 connection with your instances.

VPC Endpoints

  • VPC endpoint provides a private connection from VPC to supported AWS services and VPC endpoint services powered by PrivateLink without requiring an internet gateway, NAT device, VPN connection, or AWS Direct Connect connection.
  • Instances in the VPC do not require public IP addresses to communicate with resources in the service. Traffic between the VPC and the other service does not leave the Amazon network.
  • VPC Endpoints are virtual devices and are horizontally scaled, redundant, and highly available VPC components that allow communication between instances in the VPC and services without imposing availability risks or bandwidth constraints on the network traffic.
  • VPC Endpoints are of two types
    • Interface Endpoints – is an elastic network interface with a private IP address that serves as an entry point for traffic destined to supported services.
    • Gateway Endpoints – is a gateway that is a target for a specified route in your route table, used for traffic destined to a supported AWS service. Currently only Amazon S3 and DynamoDB.

More details @ VPC Endpoints

VPC Peering

  • VPC peering connection enables networking connection between two VPCs to route traffic between them using private IPv4 addresses or IPv6 addresses
  • VPC peering connections can be created between your own VPCs, or with a VPC in another AWS account
  • VPC peering connections can be created across regions, referred to as inter-region VPC peering connection
  • VPC peering uses existing underlying AWS infrastructure; it is neither a gateway nor a VPN connection, and does not rely on a separate piece of physical hardware.
  • VPC Peering does not have a single point of failure for communication or a bandwidth bottleneck.
  • VPC Peering connections have limitations
    • Cannot be used with Overlapping CIDR blocks
    • Does not provide Transitive peering
    • Doe not support Edge to Edge routing through Gateway or private connection

More details @ VPC Peering

VPN CloudHub

VPC CloudHub
  • AWS VPN CloudHub allows you to securely communicate from one site to another using AWS Managed VPN or Direct Connect
  • AWS VPN CloudHub operates on a simple hub-and-spoke model that can be used with or without a VPC
  • AWS VPN CloudHub can be used if you have multiple branch offices and existing internet connections and would like to implement a convenient, potentially low cost hub-and-spoke model for primary or backup connectivity between these remote offices.
  • AWS VPN CloudHub leverages VPC virtual private gateway with multiple gateways, each using unique BGP autonomous system numbers (ASNs).

Transit VPC

Transit VPC
  • A transit VPC is a common strategy for connecting multiple, geographically disperse VPCs and remote networks in order to create a global network transit center.
  • A transit VPC simplifies network management and minimizes the number of connections required to connect multiple VPCs and remote networks
  • Transit VPC can be used to support important use cases
    • Private Networking – You can build a private network that spans two or more AWS Regions.
    • Shared Connectivity – Multiple VPCs can share connections to data centers, partner networks, and other clouds.
    • Cross-Account AWS Usage – The VPCs and the AWS resources within them can reside in multiple AWS accounts.
  • Transit VPC design helps implement more complex routing rules, such as network address translation between overlapping network ranges, or to add additional network-level packet filtering or inspection

Transit Gateway (Virtual Routing and Forwarding)

  • Transit gateway enables you to attach VPCs (across accounts) and VPN connections in the same Region and route traffic between them
  • Transit gateways support dynamic and static routing between attached VPCs and VPN connections
  • Transit gateway removes the need for using full mesh VPC Peering and Transit VPC

Virtual Private Network (VPN)

VPC Managed VPN Connection
  • VPC provides the option of creating an IPsec VPN connection between remote customer networks and their VPC over the internet
  • AWS managed VPN endpoint includes automated multi–data center redundancy & failover built into the AWS side of the VPN connection
  • AWS managed VPN consists of two parts
    • Virtual Private Gateway (VPG) on AWS side
    • Customer Gateway (CGW) on the on-premises data center
  • AWS Managed VPN only provides Site-to-Site VPN connectivity. It does not provide Point-to-Site VPC connectivity for e.g. from Mobile
  • Virtual Private Gateway are Highly Available as it represents two distinct VPN endpoints, physically located in separate data centers to increase the availability of the VPN connection.
  • High Availability on the on-premises data center must be handled by creating additional Customer Gateway.
  • AWS Managed VPN connections are low cost, quick to setup and start with compared to Direct Connect. However, they are not reliable as they traverse through Internet.

More details @ Virtual Private Network

Software VPN

  • VPC offers the flexibility to fully manage both sides of the VPC connectivity by creating a VPN connection between your remote network and a software VPN appliance running in your VPC network.
  • Software VPNs help manage both ends of the VPN connection either for compliance purposes or for leveraging gateway devices that are not currently supported by Amazon VPC’s VPN solution.
  • Software VPNs allows you to handle Point-to-Site connectivity
  • Software VPNs, with the above design, introduces a single point of failure and needs to be handled.

Direct Connect

  • AWS Direct Connect helps establish a dedicated connection and a private connectivity from an on-premises network to VPC
  • Direct Connect can reduce network costs, increase bandwidth throughput, and provide a more consistent network experience than internet-based or VPN connections
  • Direct Connect uses industry-standard VLANs to access EC2 instances running within a VPC using private IP addresses
  • Direct Connect lets you establish
    • Dedicated Connection: A 1G or 10G physical Ethernet connection associated with a single customer through AWS.
    • Hosted Connection: A 1G or 10G physical Ethernet connection that an AWS Direct Connect Partner provisions on behalf of a customer.
  • Direct Connect provides following Virtual Interfaces
    • Private virtual interface – to access an VPC using private IP addresses.
    • Public virtual interface – to access all AWS public services using public IP addresses.
    • Transit virtual interface – to access one or more transit gateways associated with Direct Connect gateways.
  • Direct Connect connections are not redundant as each connection consists of a single dedicated connection between ports on your router and an Amazon router
  • Direct Connect High Availability can be configured using
    • Multiple Direct Connect connections
    • Back-up IPSec VPN connection

More details @ Direct Connect

LAGs

  • Direct Connect link aggregation group (LAG) is a logical interface that uses the Link Aggregation Control Protocol (LACP) to aggregate multiple connections at a single AWS Direct Connect endpoint, allowing you to treat them as a single, managed connection.
  • LAGs needs the following
    • All connections in the LAG must use the same bandwidth.
    • You can have a maximum of four connections in a LAG. Each connection in the LAG counts towards your overall connection limit for the Region.
    • All connections in the LAG must terminate at the same AWS Direct Connect endpoint.

Direct Connect Gateway

  • Direct Connect Gateway allows you to connect an AWS Direct Connect connection to one or more VPCs in your account that are located in the same or different regions
  • Direct Connect gateway can be created in any public region and accessed from all other public regions
  • Direct Connect gateway CANNOT be used to connect to a VPC in another account.
  • Alternatively, Direct connect locations can also access the public resources in any AWS Region using a public virtual interface.

Direct Connect with VPN

  • AWS Direct Connect plus VPN provides an IPsec-encrypted private connection that also reduces network costs, increases bandwidth throughput, and provides a more consistent network experience than internet-based VPN connections.

References

AWS VPC VPN – CloudHub Connections – Certification

VPC VPN Connections

  • VPC VPN connections are used to extend on-premise data centers to AWS
  • VPC VPN connections provide secure IPSec connections from on-premise computers/services to AWS
  • AWS hardware VPN
    • Connectivity can be established by creating an IPSec, hardware VPN connection between the VPC and the remote network.
    • On the AWS side of the VPN connection, a Virtual Private Gateway (VGW) provides two VPN endpoints for automatic failover.
    • On customer side a customer gateway (CGW) needs to be configured, which is the physical device or software application on the remote side of the VPN connection
  • AWS Direct Connect
    • AWS Direct Connect provides a dedicated private connection from a remote network to your VPC.
    • Direct Connect can be combined with an AWS hardware VPN connection to create an IPsec-encrypted connection
  • AWS VPN CloudHub
    • For more than one remote network for e.g. multiple branch offices, multiple AWS hardware VPN connections can be created via the VPC to enable communication between these networks
  • Software VPN
    • VPN connection can be setup by running a software VPN like OpenVPN appliance on an EC2 instance in the VPC
    • AWS does not provide or maintain software VPN appliances; however, there are range of products provided by partners and open source communities

Hardware VPN Connection

VPN ConnectionVPN Components

  • Virtual Private Gateway – VGW
    • A virtual private gateway is the VPN concentrator on the AWS side of the VPN connection
  • Customer Gateway – CGW
    • A customer gateway is a physical device or software application on customer side of the VPN connection.
    • When a VPN connection is created, the VPN tunnel comes up when traffic is generated from the remote side of the VPN connection.
    • VGW is not the initiator; CGW must initiate the tunnels
    • If the VPN connection experiences a period of idle time, usually 10  seconds, depending on the configuration, the tunnel may go down. To prevent this, a network monitoring tool to generate keepalive pings; for e.g. by using IP SLA.

VPN Configuration

  • VPC has an attached virtual private gateway, and the remote network includes a customer gateway, which must be configured to enable the
    VPN connection.
  • Routing must be setup so that any traffic from the VPC bound for the remote network is routed to the virtual private gateway.
  • Each VPN has two tunnels associated with it that can be configured on the customer router, as is not single point of failure
  • Multiple VPN connections to a single VPC can be created, and a second CGW can be configured to create a redundant connection to the same external location or to create VPN connections to multiple geographic locations.

VPN Routing Options

  • For a VPN connection, the route table for the subnets should be updated with the type of routing (static of dynamic) that you plan to use.
  • Route tables determine where network traffic is directed. Traffic destined for the VPN connections must be routed to the virtual private gateway.
  • Type of routing can depend on the make and model of your VPN devices.
    • Static Routing
      • If your device does not support BGP, specify static routing.
      • Using static routing, the routes (IP prefixes) can be specified that should be communicated to the virtual private gateway.
      • Devices that don’t support BGP may also perform health checks to assist failover to the second tunnel when needed.
    • BGP dynamic routing
      • If the VPN device supports Border Gateway Protocol (BGP), specify dynamic routing with the VPN connection.
      • When using a BGP device, static routes need not be specified to the VPN connection because the device uses BGP for auto discovery and to advertise its routes to the virtual private gateway.
      • BGP-capable devices are recommended as the BGP protocol offers robust liveness detection checks that can assist failover to the second VPN tunnel if the first tunnel goes down.
  • Only IP prefixes known to the virtual private gateway, either through BGP advertisement or static route entry, can receive traffic from your VPC.
  • Virtual private gateway does not route any other traffic destined outside of the advertised BGP, static route entries, or its attached VPC CIDR.

VPN Connection Redundancy

VPN Connection Redundancy

  • A VPN connection is used to connect the customer network to a VPC.
  • Each VPN connection has two tunnels to help ensure connectivity in case one of the VPN connections becomes unavailable, with each tunnel using a unique virtual private gateway public IP address.
  • Both tunnels should be configured for redundancy.
  • When one tunnel becomes unavailable, for e.g. down for maintenance, network traffic is automatically routed to the available tunnel for that specific VPN connection.
  • To protect against a loss of connectivity in case the customer gateway becomes unavailable, a second VPN connection can be setup to the VPC and virtual private gateway by using a second customer gateway.
  • Customer gateway IP address for the second VPN connection must be publicly accessible.
  • By using redundant VPN connections and CGWs, maintenance on one of the customer gateways can be performed while traffic continues to flow over the second customer gateway’s VPN connection.
  • Dynamically routed VPN connections using the Border Gateway Protocol (BGP) are recommended, if available, to exchange routing information between the customer gateways and the virtual private gateways.
  • Statically routed VPN connections require static routes for the network to be entered on the customer gateway side.
  • BGP-advertised and statically entered route information allow gateways on both sides to determine which tunnels are available and reroute traffic if a failure occurs.

VPN CloudHub

  • VPN CloudHub can be used to provide secure communication between sites, if you have multiple VPN connections
  • VPN CloudHub operates on a simple hub-and-spoke model that can be used with or without a VPC.
  • Design is suitable for customers with multiple branch offices and existing
    Internet connections who’d like to implement a convenient, potentially low-cost hub-and-spoke model for primary or backup connectivity between these remote offices

VPN CloudHub Architecture

  • VPN CloudHub architecture with blue dashed lines indicates network
    traffic between remote sites being routed over their VPN connections.
  • AWS VPN CloudHub requires a virtual private gateway with multiple customer gateways.
  • Each customer gateway must use a unique Border Gateway Protocol (BGP) Autonomous System Number (ASN)
  • Customer gateways advertise the appropriate routes (BGP prefixes) over their VPN connections.
  • Routing advertisements are received and re-advertised to each BGP peer, enabling each site to send data to and receive data from the other sites.
  • Routes for each spoke must have unique ASNs and the sites must not have overlapping IP ranges.
  • Each site can also send and receive data from the VPC as if they were using a standard VPN connection.
  • Sites that use AWS Direct Connect connections to the virtual private gateway can also be part of the AWS VPN CloudHub.
  • To configure the AWS VPN CloudHub,
    • multiple customer gateways can be created, each with the unique public IP address of the gateway and the ASN.
    • a VPN connection can be created from each customer gateway to a common virtual private gateway.
    • each VPN connection must advertise its specific BGP routes. This is done using the network statements in the VPN configuration files for the VPN connection.

AWS Certification Exam Practice Questions

  • Questions are collected from Internet and the answers are marked as per my knowledge and understanding (which might differ with yours).
  • AWS services are updated everyday and both the answers and questions might be outdated soon, so research accordingly.
  • AWS exam questions are not updated to keep up the pace with AWS updates, so even if the underlying feature has changed the question might not be updated
  • Open to further feedback, discussion and correction.
  1. You have in total 5 offices, and the entire employee related information is stored under AWS VPC instances. Now all the offices want to connect the instances in VPC using VPN. Which of the below help you to implement this?
    1. you can have redundant customer gateways between your data center and your VPC
    2. you can have multiple locations connected to the AWS VPN CloudHub
    3. You have to define 5 different static IP addresses in route table.
    4. 1 and 2
    5. 1,2 and 3
  2. You have in total 15 offices, and the entire employee related information is stored under AWS VPC instances. Now all the offices want to connect the instances in VPC using VPN. What problem do you see in this scenario?
    1. You can not create more than 1 VPN connections with single VPC (Can be created)
    2. You can not create more than 10 VPN connections with single VPC (soft limit can be extended)
    3. When you create multiple VPN connections, the virtual private gateway can not sends network traffic to the appropriate VPN connection using statically assigned routes. (Can route the traffic to correct connection)
    4. Statically assigned routes cannot be configured in case of more than 1 VPN with virtual private gateway. (can be configured)
    5. None of above
  3. You have been asked to virtually extend two existing data centers into AWS to support a highly available application that depends on existing, on-premises resources located in multiple data centers and static content that is served from an Amazon Simple Storage Service (S3) bucket. Your design currently includes a dual-tunnel VPN connection between your CGW and VGW. Which component of your architecture represents a potential single point of failure that you should consider changing to make the solution more highly available?
    1. Add another VGW in a different Availability Zone and create another dual-tunnel VPN connection.
    2. Add another CGW in a different data center and create another dual-tunnel VPN connection. (Refer link)
    3. Add a second VGW in a different Availability Zone, and a CGW in a different data center, and create another dual-tunnel.
    4. No changes are necessary: the network architecture is currently highly available.
  4. You are designing network connectivity for your fat client application. The application is designed for business travelers who must be able to connect to it from their hotel rooms, cafes, public Wi-Fi hotspots, and elsewhere on the Internet. You do not want to publish the application on the Internet. Which network design meets the above requirements while minimizing deployment and operational costs? [PROFESSIONAL]
    1. Implement AWS Direct Connect, and create a private interface to your VPC. Create a public subnet and place your application servers in it. (High Cost and does not minimize deployment)
    2. Implement Elastic Load Balancing with an SSL listener that terminates the back-end connection to the application. (Needs to be published to internet)
    3. Configure an IPsec VPN connection, and provide the users with the configuration details. Create a public subnet in your VPC, and place your application servers in it. (Instances still in public subnet are internet accessible)
    4. Configure an SSL VPN solution in a public subnet of your VPC, then install and configure SSL VPN client software on all user computers. Create a private subnet in your VPC and place your application servers in it. (Cost effective and can be in private subnet as well)
  5. You are designing a connectivity solution between on-premises infrastructure and Amazon VPC Your server’s on-premises will De communicating with your VPC instances You will De establishing IPSec tunnels over the internet You will be using VPN gateways and terminating the IPsec tunnels on AWS-supported customer gateways. Which of the following objectives would you achieve by implementing an IPSec tunnel as outlined above? (Choose 4 answers) [PROFESSIONAL]
    1. End-to-end protection of data in transit
    2. End-to-end Identity authentication
    3. Data encryption across the Internet
    4. Protection of data in transit over the Internet
    5. Peer identity authentication between VPN gateway and customer gateway
    6. Data integrity protection across the Internet
  6. A development team that is currently doing a nightly six-hour build which is lengthening over time on-premises with a large and mostly under utilized server would like to transition to a continuous integration model of development on AWS with multiple builds triggered within the same day. However, they are concerned about cost, security and how to integrate with existing on-premises applications such as their LDAP and email servers, which cannot move off-premises. The development environment needs a source code repository; a project management system with a MySQL database resources for performing the builds and a storage location for QA to pick up builds from. What AWS services combination would you recommend to meet the development team’s requirements? [PROFESSIONAL]
    1. A Bastion host Amazon EC2 instance running a VPN server for access from on-premises, Amazon EC2 for the source code repository with attached Amazon EBS volumes, Amazon EC2 and Amazon RDS MySQL for the project management system, EIP for the source code repository and project management system, Amazon SQL for a build queue, An Amazon Auto Scaling group of Amazon EC2 instances for performing builds and Amazon Simple Email Service for sending the build output. (Bastion is not for VPN connectivity also SES should not be used)
    2. An AWS Storage Gateway for connecting on-premises software applications with cloud-based storage securely, Amazon EC2 for the resource code repository with attached Amazon EBS volumes, Amazon EC2 and Amazon RDS MySQL for the project management system, EIPs for the source code repository and project management system, Amazon Simple Notification Service for a notification initiated build, An Auto Scaling group of Amazon EC2 instances for performing builds and Amazon S3 for the build output. (Storage Gateway does provide secure connectivity but still needs VPN. SNS alone cannot handle builds)
    3. An AWS Storage Gateway for connecting on-premises software applications with cloud-based storage securely, Amazon EC2 for the resource code repository with attached Amazon EBS volumes, Amazon EC2 and Amazon RDS MySQL for the project management system, EIPs for the source code repository and project management system, Amazon SQS for a build queue, An Amazon Elastic Map Reduce (EMR) cluster of Amazon EC2 instances for performing builds and Amazon CloudFront for the build output. (Storage Gateway does not provide secure connectivity, still needs VPN. EMR is not ideal for performing builds as it needs normal EC2 instances)
    4. A VPC with a VPN Gateway back to their on-premises servers, Amazon EC2 for the source-code repository with attached Amazon EBS volumes, Amazon EC2 and Amazon RDS MySQL for the project management system, EIPs for the source code repository and project management system, SQS for a build queue, An Auto Scaling group of EC2 instances for performing builds and S3 for the build output. (VPN gateway is required for secure connectivity. SQS for build queue and EC2 for builds)

References