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This is the culmination of an initiative started in February 2015 to free up unused IPv4 network addresses held by the UK government, with the aim of releasing addresses for networks not yet ready to make the leap to IPv6 and to return some money to the public purse to help pay down the deficit.
According to the CTO’s office spokesperson Hadley Beeman, DWP already owned a class A block of IPv4 addresses, which was well in use in its internal networks, but the discovery process also turned up 256 class B blocks of addresses.
IP addresses were originally assigned in four classes – A, B, C and D – with each class allocating one portion of the 32-bit address format to identify a network gateway. The first 8 bits were assigned to class A, the first 16 for B and the first 24 for C. The remainder of the bits identified the hosts on that network. In the case of class A, the system allowed 16 million hosts per network, in the case of B it allowed 65,535 per network and in the case of C it allowed 254 per network.
This gave rise to a problem because Class B IPv4 addresses were generally handed out to organisations – such as DWP – needing more than 254 hosts, even though they rarely had more than 65,535 hosts.
This meant most of the allocated addresses were never used, ultimately exacerbating the exhaustion of the IPv4 address pool.
Following some planning to minimise any impact on the frontline services delivered by DWP, GDS has now released 40 of the 256 blocks without disruption.
To accomplish this, it explored a number of alternative network structures, including Network Address Translation and IPv6, its own future need for IPv4 addresses and how best to maintain stability during the process.
“Protecting DWP’s networks and services in light of each of these factors carries a cost, so we wanted to see if we could bring in more proceeds than the exercise would cost us,” wrote Beeman on the Government Technology blog.
The prices for the addresses were developed taking into account current market conditions, demand and asset size, with input from EY and the IPv4 Market Group.
“There was significant demand for the addresses, confirming our hypothesis that others might find them useful. We also found market interest for those 40 class Bs did cover the work we had to do, plus a tidy profit – making this exercise a successful learning experience for us,” said Beeman.
GDS did not disclose how much money it had made from the sale, but added there were probably other blocks of addresses waiting to be discovered elsewhere in government and it will continue to investigate further sales.
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