IPv6 allocations, deaggregation, etc.

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1

We have decided to initiate the process of becoming IPv6 capable. We
have requested and received a block of addresses which, after reading
some of the discussion here, I fear may be too small to suit our needs
(a /48). To better understand how to proceed and in an attempt to get
it right (or close to right) the first time, I am soliciting opinions
and comments from other network operators.

It appears from earlier discussions on this list that while many
networks will not filter a /48 announcement in their routing tables,
others will. We have data centers and offices in three regions of the
globe; North America, Europe, and Asia/Pacific. We are also multihomed
as well as having some direct peering. I can break my /48 into /56 nets
for each facility. My thought process here being that if I have the
same transit providers at all sites, I can announce the /48 from my
primary location and that would get announced by the transit provider.
They would also accept my more specific routes but not announce them
outside of their AS. So traffic originating outside of my transit
provider would flow toward them following the /48 and they then move the
traffic to the final destination based on the more specific and in the
case the traffic has no more specific route, hand the traffic to my main
location for me to sort out or just black hole it. There are two
problems with this approach. 1: We are unreachable from anyone
filtering a /48 and 2: I could see a situation where traffic crosses the
Pacific, is handed to my transit provider, and then crosses the Pacific
again to get to the destination resulting in poor performance.

So it now seems to me that maybe a larger block might be the best answer
but being an "end user" the policies seem pretty restrictive on getting
a /32 though I might qualify for several /48 blocks (at least one in
each registry region). So how does one reconcile having a diverse,
multihomed organization on several continents while at the same time
trying to do the right thing, not requesting more resources than we
need, and trying to be friendly to the various networks' operations by
advertizing only what we need to? Is it unreasonable to get separate
/48 blocks for operations in Europe, North America, and Asia or possibly
two for Asia (one in China and one for Asia outside of China)? While
that still won't help us with connectivity from networks filtering
/48's, it might relieve much of the back and forth transit across oceans
to get traffic originating from and destined for the same continent to
stay there. I don't have a problem with regional backhaul tying an
office /56 to a data center announcing a /48 and using that data center
as a communications hub for the region. It also assumes a transit
provider I am paying to haul my traffic will take "more specifics" for
internal use even if they aren't advertizing them.

I am just trying to minimize the stupidity and barriers to scale on my
side of the equation.

2

The assumption that networks will filter /48s is not the whole story.

The RIRs giving out /48s do so from a single pool that only contains /48 assignments.
The RIRs give out /32s from a pool containing /32 or shorter prefixes (ie /31, /30, etc. etc).

You will find that most networks filtering /48s allow them from the pool with only /48s in it.

The root DNS servers are in /48s.

If you can justify getting a /32, then I suggest you do so, but if not then don't worry, a /48 will work just fine. The networks that do filter you will pretty soon adapt I expect.

Insert routing table explosion religious war here, with snipes from people saying that we need a new routing system, etc. etc.

So with that in mind, do your concerns from your original post still make sense?

3

From: Nathan Ward [mailto:nanog@daork.net]
Sent: Tuesday, December 22, 2009 6:34 PM
To: nanog@nanog.org
Subject: Re: IPv6 allocations, deaggregation, etc.

The assumption that networks will filter /48s is not the whole story.

...

You will find that most networks filtering /48s allow them from the
pool with only /48s in it.

That makes perfect sense.

If you can justify getting a /32, then I suggest you do so, but if not
then don't worry, a /48 will work just fine. The networks that do
filter you will pretty soon adapt I expect.

I can't in good conscience justify a /32. That is just too much space.
I believe I can, however, justify a separate /48 in Europe and APAC with
my various offices and data centers in that region coming from the /48
for that region.

Insert routing table explosion religious war here, with snipes from
people saying that we need a new routing system, etc. etc.

Eh, it isn't so bad. I could think of some ways things could have been
better (e.g. providers use a 32bit ASN as the prefix with a few "magic"
destination prefixes for multicast, anycast, futurecast and multihomed
end users use a 16-bit regional prefix with a 16-bit ASN as a 32-bit
prefix) but we are too far down the road to complain too much about that
sort of stuff.

So with that in mind, do your concerns from your original post still
make sense?

Thanks, Nathan, and let's say that I am somewhat less apprehensive than
I was.

George

4

I'm not an expert, but can/should you advertise ARIN IP space on APNIC
or RIPE, etc ? You are talking about having recieved ip space from
ARIN, tied to an ARIN AS.... I suppose it's probably more a matter of
form than anything else though.....

5

I'm not sure it's about good conscience and worrying about address space wastage anymore. I mean sure, don't go ask for a /8 or something, but follow the RIR guidelines - don't paint yourself in to a corner later by trying to save the world now.
If you are assigning addresses to customers, you should have a /32 allocation. If you are an end user of addresses, you should have a /48 portable assignment. In APNIC world anyway, I'm not sure of the terms and policies used in other regions.

6

I'm not an expert, but can/should you advertise ARIN IP space on APNIC
or RIPE, etc ? You are talking about having recieved ip space from
ARIN, tied to an ARIN AS.... I suppose it's probably more a matter of
form than anything else though.....

This happens all the time with IPv4 space and AS #'s today, why would it be any different with v6?

7

It's not.

8

That is what prompted me to say that I could probably justify a /48 in
each region out of that region's registry. We have legitimate business
operations in those regions so having an AS and IP block for those
regions should not only be justifiable but also would tend to make
things "cleaner".

9

George Bonser wrote:

We have decided to initiate the process of becoming IPv6 capable. We
have requested and received a block of addresses which, after reading
some of the discussion here, I fear may be too small to suit our needs
(a /48). To better understand how to proceed and in an attempt to get
it right (or close to right) the first time, I am soliciting opinions
and comments from other network operators.

Given you topology your direct assignment request should properly
reflect the number of sites you expect to need to need to serve. At a
/48 per site it starts to look rational.

10

Apologies in advance for the top post.

My initial idea was to use a /48, divide it up into /56 nets for each facility with /64 subnets within each facility. We would announce a /48 to our transit providers that I would expect them to announce in turn to their peers and we would also announce the more specific /56 nets to the transit providers that I would expect them not to announce to their peers. My current vlan requirements per facility would support such an addressing plan. In order to make that work, we would need the same transit providers in each region as our locations are not meshed internally. We don’t have dedicated connectivity from the US to the UK or China, for example. Currently that is not a problem as far as connectivity is concerned as my US providers appear in Europe and my China provider appears in the US. BUT when I consider the possibilities of South America and Africa and finding a transit provider that has a robust presence everywhere, my choices are very limited. I need to be multihomed and I need to be provider agnostic in my addressing.

Using that scheme above does create some potential performance issues. While my transit provider collects the traffic from a remote location and routes it to the more specific location in my network, If a provider in Europe, for example, sees only the /48 announced from the US, maybe they haul the traffic across an ocean to a point where they peer with my provider … who then must haul it back to Europe to the /56 corresponding to the destination because the original traffic source doesn’t see my /56 unless they are using the same transit provider I am.

Then based on earlier discussion on the list a while back, I was concerned that a /48 wasn’t even enough to get me connected to some nets that were apparently filtering smaller than a /48 but my mind is somewhat eased in that respect and I believe that a /48 announced from space where /48s are issued will be accepted by most people.

Then I was informed of ARIN 2009-5 which seems aimed at our situation; data centers widely separated by large geographical distances that are fairly autonomous and aren’t directly connected by dedicated links. It now seems that we (and the rest of the Internet) might be better served if we get a RIPE AS and net block for our Europe operations, and APNIC AS and net block for our APAC operations and get a regional /48 that I can split into /56 nets for the various satellite facilities within that region as those satellite offices CAN be directly connected to the regional data center which would act as the regional communications hub.

There are probably 16 different ways to slice this but I would like to get it as close to “right” as possible to prevent us having to renumber later while at the same time not taking more space than we need. A /48 per region seems like the right way to go at the present time. So we would have a /48 for the US, a /48 for Asia (and possibly one /48 dedicated to China) and a /48 for Europe. Satellite facilities would collect a /56 (or two or three) out of that regional block for their local use. Then I am free from being nailed to the same providers globally and have less chance of traffic crossing an ocean twice.

The probability of needing 200 /48s in the next several years is pretty slim and do not warrant our getting a /32 when currently three or four /48 nets will fill the requirements.

Thanks again for the input, Mick.

George

11

Apologies in advance for the top post.
   
Likewise. These are general comments, though, so I don't feel too badly... :slight_smile:

It sounds like you're on the right track. You discovered the 2009-5 Multiple Discrete Networks draft policy, which should allow you a separate /48 for each discrete network. That is somewhat orthogonal to the question of whether you should get separate resources from each RIR whose region you operate a network in. If the networks on different continents are discrete, I think the answer there is yes.

I'll also point out another resource for discussing topics like this, particularly if it appears that a change in policy would be needed to accommodate your needs: ARIN's Public Policy Mailing List (PPML), https://www.arin.net/participate/community/mailing_lists/. That's where 2009-5 came from, and I know there are still some needs unmet by current ARIN IPv6 address policy, so we're always looking for more good ideas, and feedback on the ones being discussed. At the moment, there are some very interesting discussions ongoing about how to rewrite ARIN IPv6 address policy to simplify it while making provider independent addressing more widely available and making it easier to filter traffic engineering deaggregates without accidentally filtering multihomed networks. And on the IPv4 side, there are two policy proposals on the docket to lower ARIN's minimum allocation size to /23 or /24.

I encourage anyone on this list who's interested in these topics to browse the PPML archives, look over the full list of active draft policies and policy proposals at https://www.arin.net/policy/proposals/, and subscribe to PPML. We need all the input we can get.

Thanks,
Scott Leibrand
elected volunteer member of the ARIN Advisory Council, but speaking only for myself

12

From: Scott Leibrand

It sounds like you're on the right track. You discovered the 2009-5
Multiple Discrete Networks draft policy, which should allow you a
separate /48 for each discrete network. That is somewhat orthogonal to
the question of whether you should get separate resources from each RIR
whose region you operate a network in. If the networks on different
continents are discrete, I think the answer there is yes.

The extent to which they are discrete is really more of a function of the partners those networks serve when it comes to the data centers. While most of our partners are regional, that is more by happenstance than by design and I see it changing over time as more of them operate outside of their "home" region. I also want to ensure a design that allows us to serve anyone from anywhere which further "fuzzes" how discrete each potentially is. And this is actually the part where I am having the most trouble sorting the best practice. There are some advantages to doing it either way. I could get a /45 to handle everything. Having a /45 would allow me to aggregate /48s where practical while obtaining individual /48 networks would not guarantee they would be in any sort of contiguous space and not likely allow me to aggregate them even where physically possible to do so.

One possible problem of using a US block globally is that someone might see a source address from me and assume it is originating in the US if they are using some sort of geolocation in order to direct service. That might cause me to be directed to a sub-optimal service portal depending on who I am communicating with.

Getting blocks from the regions served seems to be the way that will cause less of a problem overall at the cost of ability to aggregate the blocks should the entire network become fully physically integrated at some point in the future.

I'll also point out another resource for discussing topics like this,
particularly if it appears that a change in policy would be needed to
accommodate your needs: ARIN's Public Policy Mailing List (PPML),
https://www.arin.net/participate/community/mailing_lists/

Thanks for the pointer, Scott, I will have a look.

George

13

I can't in good conscience justify a /32. That is just too much space.

Then you need to go back to IPv6 101.

I believe I can, however, justify a separate /48 in Europe and APAC with
my various offices and data centers in that region coming from the /48
for that region.

A /48 is for a single site. If you are operating a network connecting many
sites, then you are a network operator and should get a /32 block.

Don't try to fit more into a /48 than one single site.

If you need to announce /33 or /34 prefixes to make things work, then
deal with it. Talk to providers and explain what is going on. IPv6 routing
is in its infancy and many people tend to set it up and let it run on
autopilot. There is no law saying that you must announce one and
only one /32 aggregate everywhere.

For real technical solutions to your problem, you are probably better off
going to the IPv6-ops list Subscription info is here
<lists.cluenet.de Mailing Lists;

--Michael Dillon

--Michael Dillon

14

From: Michael Dillon [mailto:wavetossed@googlemail.com]
Sent: Thursday, December 24, 2009 4:11 PM
To: nanog@nanog.org
Subject: Re: IPv6 allocations, deaggregation, etc.

> I can't in good conscience justify a /32. That is just too much
space.

Then you need to go back to IPv6 101.

This is an end user application, not an ISP application.

Something between a /32 and a /48 would suffice. The idea was that a /32 is too large (in my opinion) for an organization that isn't planning on having more than 20 sites in the next 5 years. If it were 200, that would be a different story.

If having a block smaller than a /32 breaks something, then it needs to break early so it can be addressed before things progress much further. And getting a /32 would appear to violate ARIN's policy:

6.5.8.2. Initial assignment size

Organizations that meet the direct assignment criteria are eligible to receive a direct assignment. The minimum size of the assignment is /48. Organizations requesting a larger assignment must provide documentation justifying the need for additional subnets. An HD-Ratio of .94 must be met for all assignments larger than a /48.

These assignments shall be made from a distinctly identified prefix and shall be made with a reservation for growth of at least a /44. This reservation may be assigned to other organizations later, at ARIN's discretion.

If we were to number all sites globally into a /45, we could meet the .94 HD-Ratio but with the potential problems noted in earlier traffic on this thread. I am now leaning toward expanding my request to a /45 if we go with a global block or a /46 if we go with only using ARIN allocations in North American operations.

Don't try to fit more into a /48 than one single site.

Yeah, I think I pretty much "get" that, at this point. I can hang small offices off of a data center, giving them one or more /56 nets each but yeah, trying to split a /48 between data centers is probably counter-productive.

If you need to announce /33 or /34 prefixes to make things work, then
deal with it. Talk to providers and explain what is going on. IPv6
routing
is in its infancy and many people tend to set it up and let it run on
autopilot. There is no law saying that you must announce one and
only one /32 aggregate everywhere.

Agreed. Wasn't planning on it but if we did eventually become fully integrated globally, I would probably announce the larger aggregate(s) out of one main location, maybe handing any unassigned traffic to a honey-net or something. At least if a mistake is made somewhere in addressing, that would give me a "backstop" so that we could provide a temporary fix for the problem quickly until it got fixed correctly. If someone misconfigures something and traffic goes out with the wrong subnet SA but still in our block (say someone transposes a couple of subnet digits someplace), at least the reply traffic would come back to someplace I have some control over and could route (or tunnel) the reply traffic back to where it needs to go until the root cause could be fixed. It would be ugly and slow for a while but it wouldn't be completely broken until a maintenance window where we could correct the underlying problem. Things like that offers an opportunity to fix emergencies quickly and schedule more disruptive corrective actions for a later time when people can plan for the outage. It is yet another advantage of having a larger global block over a gaggle of smaller scattered blocks.

For real technical solutions to your problem, you are probably better
off
going to the IPv6-ops list

Signed up yesterday :slight_smile:

--Michael Dillon

Thanks, Michael.

George