Philip Hunter /
06.11.2012
Originally featured on BroadcastEngineering.com
Pay TV leading charge for new Internet protocol

Up to a decade late by some estimations, the official launch of the Internet’s new protocol, IPv6, took place last week following a one-day switchover test almost exactly a year ago.

The day was heralded melodramatically as the day the Internet decides to save itself by Axel Pawlik, managing director of Ripe, the Internet Registry for Europe, Middle East and Central Asia. It was seen as an important step for broadcasters and operators, because IPv6 brings several key benefits for video transmission not present in the legacy IPv4, which still rules much of the Internet today.

IPv6 was developed initially to resolve an impending Internet address crunch. IPv4 has a 32-bit address space, meaning there are 2^32 possible addresses, which is 4,294,967,296 or about 4.3 billion — considerably less than the population of the planet and therefore inadequate for a world where many people have a number of devices with unique IP addresses, not to mention the huge number used by enterprises and governments. With the Internet of Things emerging, creating a new generation of Internet-connected devices ranging from toasters to clothing, the shortage of IPv4 addresses will become even more acute over the next few years.

IPv6 will take care of the address shortage for all time with its 128-bit address space. It creates 2^128 possible addresses, which is 18,446,744,073,709,551,616; enough to issue every household on the planet with over a billion. The original idea was that the Internet would migrate gradually and gracefully from IPv4 to IPv6 with a period of dual running. But, progress has been so slow that the Internet Society, the world body in charge of policy and development for the World Wide Web, decided it needed to speed things up.

As part of this effort, it staged a day of testing in June 2011, followed last week by World IPv6 Launch on June 6. On that day, ISPs, broadband router manufacturers, cable operators such as Comcast, web-based companies including Facebook and Google, along with router or CPE (Consumer Premise Equipment) vendors such as Cisco and D-Link, permanently enabled IPv6 for their products and services, aiming to accelerate global transition to the new protocol. Participating service providers, including AT&T, and the UK's education network, Janet, as well as Comcast, were aiming to have at least 1 percent of their residential subscribers using IPv6 when visiting websites.

But, Europe was almost conspicuous by its lack of participation in the event. This reflects a lack of preparation for IPv6 that could cause problems if work is not sped up, with migration generally further advanced in the U.S., where Comcast in particular has been a cheerleader for the protocol. But, leading UK operators, such as cable co Virgin Media (with around 4 million pay-TV subscribers), have been insisting there is plenty of time for IPv6 migration. Virgin Media is not currently providing IPv6 addresses, arguing that there is no real need yet as only 1 percent of the world’s Internet traffic is currently IPv6, which is not likely to take off suddenly in the wake of last week’s IPv6 launch day.

Virgin Media suggests that as most web sites providing services will be running in dual stack mode, that is supporting both IPv4 and IPv6 side by side, its customers will be able to access the services. This view is supported by a number of web-based companies, such as cloud services provider Elastic Hosts, which has argued it will be years before there are web servers working only in IPv6, having switched off IPv4.

But, the Comcast view is that this is a head-in-the-sand approach, given that IPv4 addresses are already virtually exhausted. However, the Internet has been able to delay the day of reckoning by hiding behind Network Address Translation (NAT), which was developed to overcome the shortage of IPv4 addresses by enabling reuse of existing addresses within enterprise networks, for example. An organization can have just one IP address serving many end users, although at the cost of operational complexity in routing incoming traffic to the correct end device.

Indeed, one of the stated advantages of IPv6 is the abolition of NAT, because there are plenty of unique addresses for everybody. This will simplify deployment, and enable built-in, end-to-end device security via the IPSec protocol.

While there is a negative dimension to IPv6, which is that it is a necessary evil required to overcome IPv4 address exhaustion that cannot be put off for ever by NAT, there is also a positive side. For broadcasters, there are some serious benefits, even if some of the advantages have been overtaken by events. One highly relevant benefit in the emerging era of OTT is inbuilt support for QoS (Quality of Service) in IPv6. Under IPv4, QoS can and has been implemented, but it has to be bolted on and effectively requires a walled garden where a given operator is in full control of all the routers and hops in between.

This is partly why IPTV services operate in a walled garden environment, since this was the only way QoS can be guaranteed under IPv4.

Of course, IPv6 cannot manufacture bandwidth that does not exist, but it does have in-built mechanisms for reserving a minimum amount of bandwidth on an end-to-end path, even when third-party networks are involved. There is scope for automatic set up and reconfiguration to maintain an end-to-end path, and in this way IPv6 could prove an enabler for robust OTT services that deliver premium HD content to large screens, which is not an immediate prospect. This is done under IPv6 via a new 20-bit field in the packet header called the “flow label,” which allows any sequence of data including a video stream to be tagged for QoS.

But, another often cited benefit of IPv6 for broadcasters may turn out to be less valuable. This is support for multicast via a feature called MLD (Multicast Listener Discovery), which is used to inform routers on the path a video stream takes that the packets should be forwarded because there is a user downstream that wants to consume that content. Since this feature was added to IPv6, however, adaptive streaming has come along, and the OTT world is rushing headlong towards MPEG DASH, which in effect provides multicast through caching. It just operates at the level of the application rather than within the network. It may be that streaming can exploit the in-built multicast capabilities of IPv6, but it has evolved to manage without them.

More fundamental workarounds, such as NAT, cannot go on delaying the day of IPv6 indefinitely, and pay TV operators do need to have a plan, and perhaps follow Comcast’s lead in being enthused by IPv6.



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