You may have read one of the many articles that have appeared recently regarding the saturation of the 32-bit IPv4 address space. For example, a recent article in The Economist discusses the issue in some detail

In practice this exhaustion primarily impacts Regional Internet Registries (RIRs) because there aren’t any more available addresses. However, the caches of addresses already held by the RIRs are expected to satisfy end-user demand for several months – possibly a few years – depending on the RIR. But, as The Economist article points out, this is not a problem likened to the "millennium bug" that comes and goes and proves to be an illusion. Correctly, the article claims, "... this time it cannot be ignored."

Red Hat and the open source community have been aware of the impending saturation of IPv4 address space for a long time. The good news is that Red Hat has been ready for a while with complete IPv6 implementations shipping today in Red Hat Enterprise Linux version 5 and 6 and Fedora.

Check out some of the top IPv6 features in Red Hat Enterprise Linux that make the migration to IPv6 simple and practical today:


  • ND protocol, the replacement for IPv4 Address Resolution Protocol (ARP), integrates Router Discovery (RDISC) and ICMP redirect mechanisms.
  • Stateless Router Auto-configuration reduces the system administration overhead by allowing central management of deployed IPv6 addresses
  • Router Discovery allows site prefixes to be announced, and gives IPv6 routers the ability to automatically give connectivity to all IPv6 hosts instead of requiring manual route updates.
  • IPsec authentication and encryption developed in conjunction with IPv6 also supports IPv4 IPsec security installations.
  • Full Dual Stack maintains simultaneous connectivity with mixed IPv4 and IPv6 networks for greater equipment ROI and simplified migration of existing systems. IPv6-only supported applications work in a IPv4 environment by using the special IPv6 address representation of an IPv4 address.
  • Tunneling crosses IPv4 networks and connects two IPv6-capable hosts even if the underlying network does not provide IPv6 connectivity.
  • Application Services includes DNS (Bind), Web server (Apache), Web proxy (Squid), mail server (Sendmail and Postfix), DHCP (dhcp), NFS, among others.
  • Stateful IPv6 Firewall (Red Hat Enterprise Linux 6) manages all connection states, enabling packets to be automatically routed to known and established connections.
  • Stateless IPv6 Firewall (Red Hat Enterprise Linux 5 and 6) acts on each individual IPv6 packet separately.
  • Transparent Proxy (Red Hat Enterprise Linux 6) is a server that acts as an intermediary for requests from a client where the client is not aware of the existence of a proxy. This feature is especially useful if the client does not provide any means of configuring a proxy.
  • IPv6 Mobility (Red Hat Enterprise Linux 6, Technical Preview) protocol allows location- independent routing of IPv6 datagrams and provides the infrastructure for mobile nodes to remain reachable via a home agent even if the mobile node switches location.

In addition, Red Hat Enterprise Linux 5 and 6 are certified against the IPv6 ReadyLogo tests:

These and other features are setting the scene for customers to migrate their Red Hat Enterprise Linux systems to IPv6 to help future-proof their networks based on business requirements.

On June 8, The Internet Society is hosting World IPv6 Day to celebrate the day IPv6 connectivity is enabled by global Internet commerce companies including major cellphone/ISP Internet providers, such as AT&T and Comcast, and network switch providers such as Cisco and Juniper Networks. This is a great opportunity to try out IPv6 connectivity. To participate go to

Visit for more migration and deployment details for complete IPv6 support in Red Hat Enterprise Linux 5 and 6, and for Fedora IPv6 test day details.