IPv6 allocations, deaggregation, etc.

George Bonser gbonser at seven.com
Wed Dec 23 02:31:05 CST 2009

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.





From: Mick O'Rourke [mailto:mkorourke at gmail.com] 
Sent: Tuesday, December 22, 2009 10:43 PM
To: Joel Jaeggli
Cc: George Bonser; nanog at nanog.org
Subject: Re: IPv6 allocations, deaggregation, etc.


Is the idea behind the /48 being looked at (keeping in mind a mixed IPv4/IPv6 environment & http://www.ietf.org/rfc/rfc5375.txt <http://www.ietf.org/rfc/rfc5375.txt%20> page 8) to have a /64 per smaller branch or VLAN, larger campus /56, and advertise out the /48 for the region?; My previous thinking and biggest thinking point is enterprise level address allocation policy, impacts to device loopbacks, voice vlans, operational simplification requirements for management and security layers etc. The feel overall has been towards needing to have a /32, a /56 per site (campus to small branch) and internally within the site /64 per VLAN. A /48 becomes too small, a /32 very much borderline. Is this a similar scenario for you? How are you justifying a /48 vs a /32? 

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