IPv6 stresses network testing

Vendors need to test their equipment to ensure it operates with both IPv6 and IPv4.

Martin Rowe, Senior Technical Editor -- Test & Measurement World, 10/1/2011 12:00:00 AM

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IPv6 (Internet Protocol version 6) is gaining in importance because IPv4 has run out of addresses. IPv4’s 32-bit address just isn’t long enough. IPv6, with its 128-bit address field, will provide enough IP addresses for a long time.

Although IPv6 has been in development for years, it is now moving into deployment. With that deployment comes the need for vendors to test equipment and networks that operate with the new protocol and also maintain IPv4 compatibility. The results of IPv6 World Test Day showed that sites that support IPv6 were able to interoperate with both IPv6 and IPv4 equipment, although the vast majority of Internet traffic on test day ran IPv4 (Ref. 1).

The 6rd technique (top) lets an IPv4 network send IPv6 packets. The DS-Lite technique (bottom) lets IPv4 and IPv6 run in parallel over an IPv6 connection.

Core network equipment, such as switches and routers, supports IPv6 using two techniques called 6rd (IPv6 rapid deployment) and DS-Lite (dual-stack-lite). These transition techniques let network operators continue to use their IPv4 DSLAMs (DSL access multiplexers) and CMTSs (cable modem termination systems) while they deploy IPv6 CPE (customer premises equipment). The figure shows the concept behind both techniques.

In the 6rd technique, networks encapsulate IPv6 into IPv4 headers. That passes, or “tunnels,” IPv6 traffic through an IPv4 network. An edge router terminates the tunnel, letting the IPv6 packets reach their destination (Ref. 2). The 6rd technique requires little change to existing networks to run because it’s based on IPv4 equipment.

In contrast, the DS-Lite technique encapsulates IPv4 over an IPv6 network. When an IPv6 CPE modem connects to an IPv6 Website, the connection remains IPv6. When either the modem or the Website supports IPv4 only, an address translator makes the conversion.

Over the last several years, IPv6 testing has focused on the core network. Now, testing is moving to edge networks and CPE. Manufacturers of home routers, for example, are implementing IPv6 in their products and they’re focusing on interoperability testing. “Gateways and CPE product require extensive testing,” said Alan Way of Spirent Communications.

Tim Winters, director of the IPv6 Consortium at the UNH-IOL (University of New Hampshire Interoperability Lab), noted that manufacturers of home routers test their products to make sure that IPv6 packets will pass through their products’ firewalls. “The IETF (Internet Engineering Task Force) has developed a default value for a firewall. It lets engineers figure out how to implement their firewalls.”

The UNH-IOL has held several IPv6 “plugfests” where manufacturers can test their products with a variety of network equipment. “We’ve seen a lot of interest in testing home routers for 6rd and DS-Lite compatibility as well,” Winters said. T&MW

REFERENCES
1. Rowe, Martin, “The Internet was tested,” Rowe’s and Columns blog, June 13, 2011. www.tmworld.com.
2. “Best practices for Deploying IPv6 over Broadband Networks,” Ixia, May 2011. www.ixiacom.com.

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