IPv4 addresses are widely used, but the limited number of IPv4 addresses restricts the development of the Internet. Compared with IPv4 addresses, IPv6 addresses are more sufficient and allow more types of devices to access the Internet. Elastic Compute Service (ECS) supports both IPv4 and IPv6 addresses.

Comparison between IPv4 and IPv6

Item IPv4 IPv6
Address length 32 bits (4 bytes) 128 bits (16 bytes)
Number of addresses 2^32 2^128
Address format xxx.xxx.xxx.xxx

Where xxx is a decimal number that can range from 0 to 255. Each x is a decimal integer, and leading zeros can be omitted.



Where each x is a hexadecimal number, and leading zeros can be omitted. You can use a double colon (::) once in an IPv6 address to indicate a series of zeros.

Example: CDCD:0000:0000:0000:8475:1111:3900:2020=CDCD::8475:1111:3900:2020

Address Resolution Protocol (ARP) Uses broadcast ARP Request frames to resolve an IP address to a link layer address. Uses multicast neighbor solicitation messages to resolve an IP address to a link layer address.
Security Implements a security mechanism based on applications and cannot provide protections at the IP layer. Supports packet fragmentation to ensure data confidentiality and integrity and provides security at the IP layer.
LAN connection Connects to LANs by using network interfaces. Can work with Ethernet adapters and is supported over virtual Ethernet networks between logical partitions.
Address type
  • Unicast address
  • Multicast address
  • Broadcast address
  • Unicast address
  • Multicast address
  • Anycast address


  • Only ECS instances that reside in virtual private clouds (VPCs) support IPv6 addresses. For information about ECS instance types that support IPv6 addresses, see Instance families.
  • IPv6 addresses support communication over the internal network within VPC. To use an IPv6 address to communicate with the Internet, you must purchase a public bandwidth plan for the IPv6 address on the IPv6 Gateway page in the VPC console. For more information, see Purchase a public bandwidth plan for an IPv6 address.
  • Only a single IPv6 address can be assigned to each ECS instance.