Sorry, but there are knowledgeable people here and I wondered if anyone knew where to look. I have been using the same block of IP addresses for more than 15 years and I now have to change ISP. This is from the old Nildram allocation, and now of course run by TalkTalk. I need to change ISP soon as we will be getting connectivity (FTTP from Openreach) that TalkTalk doesn't resell. I wondered if any smaller ISP that uses TalkTalk as upstream supplier would be able to let me continue to use the same address range. Sounds like a simple matter of routing!
Why would you want to use the same block, you shouldn't be referencing IP addresses. You should be referencing DNS names.
Even if you need a static address you still shouldn't reference that address as it makes it harder to move.
BTW routing is far from simple because people move small address blocks around so making very large routing tables and lots of updates.
If someone in the USA wants to get to your address than their router needs to have a route defined for your block and that can mean hundreds of thousands of entries for each of the small blocks that exist and the consequential updates that go with them. This applies to everywhere.
Its the reason routeable IPv4 addresses were running out but the authorities have been reclaiming them for a number of years in an attempt to make things manageable.
IPv6 works differently so you don't actually ever own a full address like some do with IPv4.
Fortunately nobody told my service provider (AAISP). I have an IPv6 /48 allocation which gives me more subnets than anyone could possibly use. Each subnet has more addresses than the whole of the IPv4 internet. I "own" the addresses as much as anyone can own IPv4 addresses. In other words they are mine for as long as I stay with that service provider, exactly the same as IPv4. If I could justify it and was willing to pay, I could have my own Provider Independent IPv6 allocation that could be moved from one service provider to another. These used to be available for IPv4 but are no longer available.
They probably did. I expect they obeyed the rules when they allocated it to you.
They shouldn't need to change even if you move provider unless they are allocating it out of their "private" address space.
Well yes you can own a /48 if you want but you don't own the rest of the IPv6 address. In theory you can move the whole thing quite easily as you will just get a different link address from your new supplier and the /48 address bits will remain the same. Its the IPv6 DNS function that actually finds you and provides the complete address you are on. In theory the routing table for IPv6 is a hierarchy so you can get to anyone by following the various address fields in order. Meaning an ISP only needs a small routing table (tens rather than hundreds of thousands of entries). However many ISPs have multiple links to other ISPs so the routing tables grow to reflect the available routes. So IPv6 routing tables could go into a thousand or so entries.
It shouldn't really cost you any more than a nominal admin fee to move your IPv6 address block. Its not exactly difficult to do. A minute or two online should be all that's needed provided you have a domain registered to it.
I know, but rewriting zone files is tedious, and having had an inept provider for some time, and a broken local DNS server for other time, I've got dozens of config files with just the IP written in them. Also it's a 0-15 block which is easy to remember.
I realistically expect to die long before IPv6 can be used alone.
see if it's assigned as PI or PA space, if the latter there's zero chance, even if the former you're going to need a *very* understanding ISP, about 20 years ago, advertising a /24 subnet was about the smallest they were interested in ...
Thanks. I assumed that only routing within TalkTalk would be needed if the ISP was connected to the world via them, as it is a /28 block within an /18 block assigned to Tiscali, and therefore now TalkTalk. It does say "ASSIGNED PA", whatever that means.
Of course that'll mean you can't parallel run/test the new connection before cancelling the old connection, so you'll have more downtime for the changeover ...
AAISP also have TalkTalk back haul, worth talking to them. You stand a very good chance of talking to someone who will understand the problem and know what is posible. AAISP can also supply service over FttP.
Is your Openreach FTTP part of a local full fibre rollout? ie Openreach replacing the copper local end with fibre and providing an fibre NTE with POTS ports etc.?
Sort of surprised that TalkTalk can't supply you with service over that just as they do VDSL/ADSL. Has some one has confused this full fibre copper replacement with Fibre to the Premisis on Demand have they? Very few ISPs sell that.
The upper part of an IPv6 address is assigned dynamically by the service providers, or at least that's what the rules said last time I looked.
Its supposed to stop the stupid routing tables that you get with IPv4 where people take the whole IPv4 address and connect it to some random part of the internet.
With IPv6 you should be assigned the bottom 64 bits of the 128 bit address as a static address.
Then there is a link local address which is assigned at run time by negotiation with whatever service provider you are attached to. This makes the routeable part (the top 64 bits) unique to you and to the service provider. So to route to you the upper level routers only need to know which link local addresses have been assigned to your service provider and send stuff to them. They do not need to follow your link local address around if you move provider because you will be assigned a new one by your new provider.
If you start hard coding complete IPv6 addresses then expect problems if you move service provider.
What it means is that the bottom 64 bits are effectively the MAC address and can uniquely identify a particular device if desired. You can plug that device in on any router anywhere and be able to find it and talk to it.
It can also be assigned statically by the service provider.
Many service providers will statically assign a /48, /56 or /60 block, so you get lots of 64-bit subnets which you can use as you please. One provider (in India) assigns /62 blocks, giving only four subnets.
No, the link local address is nothing to do with the service provider. It is purely local.
The service provider knows nothing about your link local address. Hosts on the local subnet communicate with each other and their local router using the link local address, but a separate public address is negotiated for internet traffic. The router receives the prefix from the service provider and allocates /64 subnets to appropriate LAN interfaces on the router. The prefix appropriate to a particular interface is communicated to the host by a Router Advertisement or dhcpv6. The host selects its address within the subnet either by stateless address autoconfiguration (SLAAC) where it is derived from the MAC address or it can be randomly or manually set. It can also be set by some routers using dhcp6.
Many devices use privacy addressing (RFC4941) where the bottom 64 bits are randomly selected and changed at regular intervals, so it is harder to track a particular device. If there are long lasting sessions, these are not closed when a new address is assigned, so it is possible for one host to accumulate many addresses simultaneously. A stale address is only relinquished when the last session using it has closed down. You can of course only talk to a device if the firewall rules allow it.
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