5 ms·

But the point is that they're not using it. If it's not addressable from the internet, why not use 10.0.0.0/8 instead?

gertrunde 5y ago
It's not relevant whether or not it's accessible from the internet. And that 9/8 allocation predates RFC1918 by at least four years.
- tyingq 5y ago
  I'm curious what you mean by this. RFC1918 is just an update for earlier RFCs that go back farther in time, like RFC1597. And IBM people are credited on the relevant RFCs. IBM is basically hoarding a bunch of addresses where there's no technical reason to. I get that they aren't required to do anything about it, but it does seem topically relevant.
  - wiseleo 5y ago
    IBM owns Softlayer. They may have a legitimate need for that many addresses. :)
aparks517 5y ago
For some applications, it's valuable to have globally-unique addresses even if they're not (all) broadly accessible from the open Internet. For example, if you're building private links between networks which don't share an authority for distributing private network addresses (they're administered by different companies or organizations perhaps). I don't know how common this is anymore, but I've seen it in the past.
- cesarb 5y ago
  > For some applications, it's valuable to have globally-unique addresses even if they're not (all) broadly accessible from the open Internet. For a real-life example of that: according to documentation which can be found at its website, the Brazilian Central Bank has been allocated a full /18 for the national inter-bank network; each financial institution connected to that network receives a /27 or a /28 (or a pair of them) from that range. If you look up that address range on bgp.he.net, you'll find out that it's not announced to the public Internet at all.
- JAlexoid 5y ago
  There's a case for these, but it's not as broad as needing 16 million publicly usable IPs for IBM alone.
numpad0 5y ago
Why 10.0.0.0/8 is as it is now and why IBM used to be 9.0.0.0/8 in the first place?
- FuriouslyAdrift 5y ago
  Before classless addressing, RFC1918 set out a reserved IP space in each class. 10.0.0.0/8 was set aside in the class A range by ARIN.
dheera 5y ago
You might want to allow specific machines to be addressable from the internet. Also, NATs were buggy back then and many pieces of software simply wouldn't work unless you had a real IP address. VLANs and other advanced router features didn't really exist, either.
jcrawfordor 5y ago
Here's a little different approach to the issue: because IBM is using IP addresses the way they were intended. Private IP ranges are not a good thing, they are a necessary evil. NAT was developed as essentially a hack, originally more to solve tricky routing situations, but later more to allow broad use of reserved range IPs. But the original intent was always that all hosts would have a unique address, regardless of where they were or were not reachable form (or advertised to). This is a significantly better situation than the modern world of widespread use of reserved ranges and NAT, because it meant that there would not be addressing conflicts even between two private networks. Or, more practically, it meant that setting up tunneled connectivity (VPN, MPLS, whatever) between networks not advertised to the public internet always works properly, because those networks are using IP addressing as intended and thus can simply advertise their routes to each other. Private IP ranges for "private" hosts are an adaptation to the limitations of IPv4 space, not any kind of design ideal. It's an awkward solution to a bad problem that makes numerous real-world IT situations more difficult, most commonly the case of setting up VPNs between private networks and being forced to introduce NAT because they are both using overlapping private IP space. A very common but small example of this is the need to choose "unusual" private IP prefixes for VPN networks (like 10.106.41.0/24 or something else sort of randomly selected), because if you use something "simple" like 192.168.1.0/24 or 10.0.0.0/24 you are 100% guaranteed to run into route conflicts because of people's home and small business networks using these ranges internally. If everyone used properly allocated IPs, even on private networks, we simply wouldn't have this problem! IPv6 offers us a bit of a reset opportunity since it was designed to have enough /64s available to allow use on private networks. Hopefully people understand this and use IPv6 the way it was intended!
- AviationAtom 5y ago
  You spoke of one of my most annoying issues as a VPN user. Ultimately I resolved it by myself using a non-standard private IP range at home. Any IT person that might ever use 192.168.0.0/16 space for their VPN network is an absolute masochist.
- otabdeveloper4 5y ago
  > Private IP ranges are not a good thing, they are a necessary evil. Well, no. The word "Internet" is short for "Inter-network exchange". The original idea of the internet was to allow LANs to talk to each other. Not to give every single device on Earth its own unique key.

It's not relevant whether or not it's accessible from the internet. And that 9/8 allocation predates RFC1918 by at least four years.

tyingq 5y ago
I'm curious what you mean by this. RFC1918 is just an update for earlier RFCs that go back farther in time, like RFC1597. And IBM people are credited on the relevant RFCs. IBM is basically hoarding a bunch of addresses where there's no technical reason to. I get that they aren't required to do anything about it, but it does seem topically relevant.
- wiseleo 5y ago
  IBM owns Softlayer. They may have a legitimate need for that many addresses. :)

aparks517 5y ago

For some applications, it's valuable to have globally-unique addresses even if they're not (all) broadly accessible from the open Internet. For example, if you're building private links between networks which don't share an authority for distributing private network addresses (they're administered by different companies or organizations perhaps). I don't know how common this is anymore, but I've seen it in the past.

cesarb 5y ago
> For some applications, it's valuable to have globally-unique addresses even if they're not (all) broadly accessible from the open Internet. For a real-life example of that: according to documentation which can be found at its website, the Brazilian Central Bank has been allocated a full /18 for the national inter-bank network; each financial institution connected to that network receives a /27 or a /28 (or a pair of them) from that range. If you look up that address range on bgp.he.net, you'll find out that it's not announced to the public Internet at all.
JAlexoid 5y ago
There's a case for these, but it's not as broad as needing 16 million publicly usable IPs for IBM alone.

numpad0 5y ago

Why 10.0.0.0/8 is as it is now and why IBM used to be 9.0.0.0/8 in the first place?

FuriouslyAdrift 5y ago
Before classless addressing, RFC1918 set out a reserved IP space in each class. 10.0.0.0/8 was set aside in the class A range by ARIN.

dheera 5y ago

You might want to allow specific machines to be addressable from the internet. Also, NATs were buggy back then and many pieces of software simply wouldn't work unless you had a real IP address. VLANs and other advanced router features didn't really exist, either.

jcrawfordor 5y ago

Here's a little different approach to the issue: because IBM is using IP addresses the way they were intended. Private IP ranges are not a good thing, they are a necessary evil. NAT was developed as essentially a hack, originally more to solve tricky routing situations, but later more to allow broad use of reserved range IPs. But the original intent was always that all hosts would have a unique address, regardless of where they were or were not reachable form (or advertised to). This is a significantly better situation than the modern world of widespread use of reserved ranges and NAT, because it meant that there would not be addressing conflicts even between two private networks. Or, more practically, it meant that setting up tunneled connectivity (VPN, MPLS, whatever) between networks not advertised to the public internet always works properly, because those networks are using IP addressing as intended and thus can simply advertise their routes to each other. Private IP ranges for "private" hosts are an adaptation to the limitations of IPv4 space, not any kind of design ideal. It's an awkward solution to a bad problem that makes numerous real-world IT situations more difficult, most commonly the case of setting up VPNs between private networks and being forced to introduce NAT because they are both using overlapping private IP space. A very common but small example of this is the need to choose "unusual" private IP prefixes for VPN networks (like 10.106.41.0/24 or something else sort of randomly selected), because if you use something "simple" like 192.168.1.0/24 or 10.0.0.0/24 you are 100% guaranteed to run into route conflicts because of people's home and small business networks using these ranges internally. If everyone used properly allocated IPs, even on private networks, we simply wouldn't have this problem! IPv6 offers us a bit of a reset opportunity since it was designed to have enough /64s available to allow use on private networks. Hopefully people understand this and use IPv6 the way it was intended!

AviationAtom 5y ago
You spoke of one of my most annoying issues as a VPN user. Ultimately I resolved it by myself using a non-standard private IP range at home. Any IT person that might ever use 192.168.0.0/16 space for their VPN network is an absolute masochist.
otabdeveloper4 5y ago
> Private IP ranges are not a good thing, they are a necessary evil. Well, no. The word "Internet" is short for "Inter-network exchange". The original idea of the internet was to allow LANs to talk to each other. Not to give every single device on Earth its own unique key.