IPv4 exhaustion leads to Relish using CGNAT
Relish has started to provide a fast broadband service in the parts of London where it is most needed in the last few months and its use of 4G LTE combined with a home router and scooter delivery is making it popular in the parts of London where people are finding it difficult to get good speeds.
One aspect of the service has recently come to light and that is that the service uses Carrier Grade NAT (CGNAT), as a way to share a limited number of IPv4 addresses between the users of a service. CGNAT is not new, in fact for mobile broadband it has been common for some years, and BT Consumer and PlusNet have both ran trials of CGNAT to evaluate it as a stop gap solution before more widespread IPv6 adoption takes place.
"Due to the global exhaustion of legacy IP addresses (IPv4) ISPs around the world have been forced to implement CGNAT solutions to enable a single IP address to be shared by many customers – this is becoming increasingly common.
We have implemented a solution used by many network operators and ISPs for fixed and mobile services. This was tested extensively prior to launch using a range of applications including online gaming with no issues reported. We do acknowledge that it is difficult to test every scenario that may exist in every application and as a result we are going to release a block of public IPv4 addresses to our consumer customers. This will be subject to some qualifying criteria and an additional monthly fee. These will be available from the 1st September via our customer care teams.
As a longer-term solution we are implementing a project to allow customers to use IPv6 addressing."Will Harnden – Marketing Director
The vast majority of broadband users are not going to be aware of CGNAT and while NAT on consumer routers can break some applications the carrier grade version is much better at ensuring problematic protocols are handled sensibly.
The news that Relish is working on a paid option for people to have a public IPv4 address is welcome and may make life easier for some home workers and offices where the Relish wireless router has replaced their fixed broadband. Of course long term once IPv6 is more widely adopted this problem of limited IP ranges goes away.
The 4G LTE service sold by Relish is advertised as up to 50 Mbps and certainly we are seeing people getting those sorts of speeds, below is a comparison of the median speeds for Relish users compared to all other broadband connections in the three London Boroughs where most of the Relish coverage is located.
|Speed test results for Relish compared to everyone else|
|Authority||Relish Median Download Speed||Relish top 25% percentile Download||Relish Median Upload Speed||Others Median Download||Others top 25% percentile Download||Others Median Upload|
|Tower Hamlets London Borough||16.8 Mbps||27.3 Mbps||3.3 Mbps||15.4 Mbps||32.2 Mbps||1.2 Mbps|
|City of Westminster||21.5 Mbps||35.9 Mbps||1.2 Mbps||13 Mbps||25.3 Mbps||1 Mbps|
|City and County of the City of London||17.7 Mbps||23.2 Mbps||3 Mbps||14.7 Mbps||38.9 Mbps||2.7 Mbps|
|Combined London Region
(Others figures top 25% is high from Virgin Media and FTTC coverage in the suburbs of Greater London)
|18.9 Mbps||23.6 Mbps||2.1 Mbps||21.5 Mbps||47.7 Mbps||2.7 Mbps|
The figures may not look too exciting to those who regularly see 60 to 100 Mbps speeds every day, but without the tie to a fixed landline and unlimited usage which is hard to find via mobile 4G tethering they have a sizeable market and impossible for £20/month. The focus in London has been the slow speeds in the City of London and Relish do offer a real opportunity to get speeds well beyond those that people with long ADSL2+ lines as their only option can currently get.
We have been chasing this story for a week or so and hope to have pricing information soon on public IPv4 addressing and have improved the auto detection of Relish customers on our speed test so that more results can appear on our maps and in our data analysis.
Update Friday 29th August We have been informed that the price for a static public IPv4 address will be £10/month. The testing of IPv6 addresses is underway and we believe we have seen some of these tests on our speed tester too since Relish launched.
Obviously £10 per month for an IPv4 address may seem a lot but when the basic service is £20 per month with no voice line rental payment needed, the total price is still not unreasonable particularly as download and upload speeds from fixed line services are so patchy in areas like Westminster and the City of London.