Network interface
KakaoCloud network interfaces act as virtual network cards, enabling resources in a VPC to be logically connected for communication. Users can create, modify, and delete network interfaces, as well as attach them to instances within the same availability zone or detach existing secondary network interfaces.
- Multi-IP per network interface will be supported in the future.
Components
Network interfaces consist of the following components:
- Primary private IPv4 address within the VPC’s IPv4 address range.
- Secondary private IPv4 address within the VPC’s IPv4 address range.
- One public IP address per private IPv4 address.
- One or more security groups.
- MAC address.
Concepts
The following concepts are key to understanding network interfaces.
1. Primary network interface
The primary network interface refers to the default network interface created when an instance is launched. Each instance must have one primary network interface, which cannot be detached.
2. Secondary network interface
Secondary network interfaces are additional interfaces attached to an instance, beyond the primary network interface. The number of secondary network interfaces that can be attached depends on the instance family and size. Secondary network interfaces can be added freely (within the maximum allowed) and can be detached or connected.
3. Primary private IPv4 address assigned to network interface
Each network interface is assigned a primary private IPv4 address within the CIDR block of the VPC subnet.
4. Public IP address assigned to network interface
A public IP can be attached to the private IPv4 address of a network interface. Once the public IP is attached, the network interface can communicate with the outside world through the internet gateway until the public IP is detached.
5. Modify allowed IP for packet sending
You can add or delete allowed IP addresses or CIDR blocks for each network interface. This allows the attached instance to function as a NAT instance.
6. Security groups
Security groups can be assigned to network interfaces. All instance types, except for Bare Metal Server (BMS) instances, require at least one security group. For detailed information on security groups, refer to security groups.
Attache network interface
When attaching a network interface, consider the following:
- Only network interfaces within the same availability zone as the instance can be assigned and attached to the instance.
- Secondary network interfaces can be detached even when the instance is running, but the primary network interface cannot be detached under any circumstances.
- The instance must be in either the
ActiveorStoppedstate when attaching a network interface. - A network interface can be created with a manually assigned private IPv4 address, but the assigned IP address must be within the CIDR range of the instance's subnet.
- If two or more network interfaces are connected to the same subnet in an instance, asymmetric routing issues may arise. In this case, requests and responses might take different paths, leading to packet blocking by firewalls. Therefore, it’s recommended to connect interfaces to different subnets.
- The number of network interfaces that can be attached to an instance depends on the instance family and size.
- The network bandwidth will not increase by simply attaching multiple network interfaces, except in the case of the Bare Metal Server instance bonding feature.
- When using multiple network interfaces, static routing configuration may be required within the instance for proper operation.
The number of network interfaces by instance family and size
The maximum number of network interfaces that can be attached varies by instance family and size.
General
For the general instance family, the maximum number of network interfaces by size is as follows:
| Instance Family | Size | Max Network Interfaces |
|---|---|---|
| m2a | large | 3 |
| xlarge | 4 | |
| 2xlarge | 4 | |
| 4xlarge | 8 | |
| 8xlarge | 8 | |
| 12xlarge | 8 | |
| 16xlarge | 15 | |
| 24xlarge | 15 | |
| m3az | large | 3 |
| xlarge | 4 | |
| 2xlarge | 4 | |
| 4xlarge | 8 | |
| 6xlarge | 8 | |
| 8xlarge | 8 | |
| t1i | nano | 2 |
| micro | 2 | |
| small | 2 | |
| medium | 3 | |
| large | 3 | |
| xlarge | 4 | |
| 2xlarge | 4 |
Memory Optimized
For the memory-optimized instance family, the maximum number of network interfaces by size is as follows:
| Instance Family | Size | Max Network Interfaces |
|---|---|---|
| r2a | large | 3 |
| xlarge | 4 | |
| 2xlarge | 4 | |
| 4xlarge | 8 | |
| 8xlarge | 8 | |
| 12xlarge | 8 | |
| 16xlarge | 15 | |
| 24xlarge | 15 | |
| baremetal | 2 |
Compute Optimized
For the compute-optimized instance family, the maximum number of network interfaces by size is as follows:
| Instance Family | Size | Max Network Interfaces |
|---|---|---|
| c2a | large | 3 |
| xlarge | 4 | |
| 2xlarge | 4 | |
| 4xlarge | 8 | |
| 8xlarge | 8 | |
| 12xlarge | 8 | |
| 16xlarge | 15 | |
| 24xlarge | 15 |
Accelerated Computing
For the accelerated computing instance family, the maximum number of network interfaces by size is as follows:
| Instance Family | Size | Max Network Interfaces |
|---|---|---|
| gn1i | xlarge | 3 |
| 2xlarge | 3 | |
| 4xlarge | 3 | |
| 8xlarge | 4 | |
| 12xlarge | 8 | |
| 16xlarge | 4 | |
| gf1i | 6xlarge | 4 |
| 12xlarge | 8 | |
| 24xlarge | 15 | |
| p1i | baremetal | 2 |
| p2i | 6xlarge | 4 |
| 12xlarge | 8 | |
| 24xlarge | 15 | |
| p2a | baremetal | 2 |
Video Transcoding
For the video transcoding instance family, the maximum number of network interfaces by size is as follows:
| Instance Family | Size | Max Network Interfaces |
|---|---|---|
| vt1a | 4xlarge | 8 |
| 8xlarge | 8 | |
| 32xlarge | 15 |