IPv6 design, deployment, standards, and best practices.
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wintermute000
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IPv6 addressing design help

Mon Feb 04, 2013 11:15 pm

Over the next year I want to implement and develop ipv6 network (dual stack) in my environment and hence starting to look at the details.
The recommendations all say /64 even on point to point links (I can see the logic certainly).

However I'm not in a 'normal' enterprise environment, we're a mini service provider (long story) but with lots of enterprise-y requirements as well, its very much a hybrid environment. In short having 16 bits for site addressing is not ideal, as we are VRF-ed and it makes it harder to split the subnets up in a 'visually' pleasing way (or am I too stuck in ipv4 thinking?). For example, I am planning on moving to at least 4 distinct OSPF areas, and within these areas we have sites with over 1000 vlans (that we need to keep separated this way e.g. serviced apartments, offices). So what would you guys do?

e.g. lets assume /48 supernet as normal from ISP.
Then assume follow guidelines and make /64 the smallest subnet.
I need minimum 1k subnets per site. so that's 10 bits, each site is a /54?
So now I have 6 bits left to divide at least 4 OSPF areas (obviously I want more buffer!) AND fit sites into (each area must fit at least 64 sites if not 128!, we already have 30+ in some).

How would I do it in a summarised manner, or do I have to abandon the /64 idea, OR tackle the issue of a /48 allocation....

Second, we haven't talked to APNIC or our upstream ISPs, but I don't think we'll fit in with the usual /48 model.
if we're dishing out public IPs to our customers (presently we own a /21 and /22 of v4), then what's the optimum model of allocation? What if our customers demand a /48 each for example? not that we have any customers big enough to remotely use the full /48....

In a perfect world would it be something like this to give me enough headroom?
/64 subnets
/53 sites (so 2047 VLANS/subnets per site)
/46 each OSPF area (so 127 sites per area)
/42 overall (so 15 OSPF areas) - request /42 off APNIC

Appreciate everyone's input

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jdsilva
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Re: IPv6 addressing design help

Mon Feb 04, 2013 11:30 pm

/64 subnets

/126 for p2p links

Stop thinking like IPv4. You break IPv6 functions if you don't use /64's.

You should get a /48 from your provider(s). If you are a provider and will hand out /48's to your customers then get your own allocation from an RIR.

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wintermute000
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Re: IPv6 addressing design help

Mon Feb 04, 2013 11:36 pm

So bite the bullet and get a /32 off RIR?

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zerojunkie
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Re: IPv6 addressing design help

Tue Feb 05, 2013 12:22 am

jdsilva wrote:You should get a /48 from your provider(s).


Been at least a few years since I tested the IPv6 waters, but one point I couldn't help but take away was why someone wouldn't get PI space. With the vehement opposition to NAT and all it sounds like you'd be putting your entire IP scheme at the mercy of the ISP you got them from. Doesn't seem like fun unless you're doing a limited deployment perhaps just to a DMZ or something.

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wintermute000
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Re: IPv6 addressing design help

Tue Feb 05, 2013 12:34 am

yeah I'm going to go away and read APNIC guidelines again. I believe as we are a registered ASN with IPv4 /21 and /22 already we can easily justify being allocated a IPv6 /32.

When we go v6 I have to be ready to dish /48s.... gah
Perhaps get away with specifying if you want a /48 you need your own site, if you're in one of our sites hosted then maximum say /60 or whatever for you.
Doesn't look like so many bits does it once you start slicing it up in a way that you can still summarise....

/64 subnets (/60 per customer who wants more than a single subnet - 90% of our customers small business, our standard allocation right now is a RFC1918 /27 and 90% of them are fine with this or a single public IP)
/48 sites / big customers with their own site
/38 each OSPF area
/32 overall

I feel like I'm so late to the party, yet in all seriousness, in the past year, nobody internally or any customer has mentioned the phrase IP6 to me, not even once.

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mellowd
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Re: IPv6 addressing design help

Tue Feb 05, 2013 5:58 pm

Get a /32 if you can and subnet on the nibble boundries. If you subnet anywhere else you're in a world of hurt.

And personally I would stick with a single area 0...


Sent on the move...

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wintermute000
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Re: IPv6 addressing design help

Tue Feb 05, 2013 7:27 pm

am I being far too old school then? (you know, max 50 routers per area yada yada).

My main concern is not my 2921s etc.
Its just quite a few buildings in area 1, I have 3560s/3750Xs as collapsed cores

Being in area 1, I can't NSSA the them off so they participate in same OSPF as the entire area.
I'm worried as the network grows I'll have to introduce workarounds like EIGRP redistribution (which incidentally would save on paying for IP services licenses lol) or go FHRP (ugh!) if the multilayers can't cope with the LSA processing. Mind you I haven't seen any stability or CPU alerts yet.....
I was going to move some stuff around areas to go to a nice clean central 0 then each WAN a separate area design. (involves redistributing area 0 in another vrf into a new area 0 process on an ASA... but nevermind)

On holiday as of today (yay) will nibble around the ideas (no pun intended lol) thanks for your guidance!

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mellowd
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Re: IPv6 addressing design help

Wed Feb 06, 2013 2:39 am

I'm happy with hundreds of routers in a single area.



Sent on the move...

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Heath
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Re: IPv6 addressing design help

Thu Jul 18, 2013 8:13 am

I found this site helpful in coming up with my IPv6 addressing plan. http://www.gestioip.net/docu/hierarchic ... _plan.html

HzE
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Re: IPv6 addressing design help

Tue Oct 22, 2013 2:42 am

jdsilva wrote:/64 subnets

/126 for p2p links

Stop thinking like IPv4. You break IPv6 functions if you don't use /64's.


Is there any other reason not to subnet IPv6 -addresses into smaller chunks than /64 besides breaking the Stateless Address Autoconfiguration -functionality? So If we talking about networks where all IP-addresses are configured by hand is there any harm in using smaller prefixes?

And I guess using /127 is even okay for p2p-links, at least according to RFC 6164 though I've noticed that not all vendors support /31 in IPv4.


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