AWS -VPC & Security Group
VPC
Amazon Virtual Private Cloud (Amazon VPC) enables you to launch AWS resources into a virtual network that you've defined
Amazon VPC is the networking layer for Amazon EC2.
Security Group
By default, each security group supports up to 50 rules and each network interface can have up to 5 security groups, for a maximum of 250 rules per interface.
You can increase the number of rules per security group if you decrease the number of security groups per interface, ensuring that the total number of rules on an interface doesn't exceed 250.
Note: By default, you have 50 rules in the inbound direction and 50 rules in outbound direction per security group. A limit change to the number of rules per security group applies to both inbound and outbound rules.
For example:
5 security groups per interface x 50 rules per security group = 250
4 security groups per interface x 62 rules per security group = 248
3 security groups per interface x 83 entries per security group = 249
2 security groups per interface x 125 entries per security group = 250
Security Groups
VPC Peering
A VPC peering connection is a networking connection between two VPCs that enables you to route traffic between them using private IPv4 addresses or IPv6 addresses. Instances in either VPC can communicate with each other as if they are within the same network. You can create a VPC peering connection between your own VPCs, or with a VPC in another AWS account. The VPCs can be in different regions (also known as an inter-region VPC peering connection).
A VPC peering connection helps you to facilitate the transfer of data. For example, if you have more than one AWS account, you can peer the VPCs across those accounts to create a file sharing network. You can also use a VPC peering connection to allow other VPCs to access resources you have in one of your VPCs.
Amazon Virtual Private Cloud Connectivity Options
https://d1.awsstatic.com/whitepapers/aws-amazon-vpc-connectivity-options.pdf