cidrIpv6

The IPv6 address range. You can either specify a CIDR block or a source security group, not both. To specify a single IPv6 address, use the /128 prefix length.

Amazon Web Services canonicalizes IPv4 and IPv6 CIDRs. For example, if you specify 100.68.0.18/18 for the CIDR block, Amazon Web Services canonicalizes the CIDR block to 100.68.0.0/18. Any subsequent DescribeSecurityGroups and DescribeSecurityGroupRules calls will return the canonicalized form of the CIDR block. Additionally, if you attempt to add another rule with the non-canonical form of the CIDR (such as 100.68.0.18/18) and there is already a rule for the canonicalized form of the CIDR block (such as 100.68.0.0/18), the API throws an duplicate rule error.