RE: [afripv6-discuss] IPv6 rollout.

Latif Ladid (''The New Internet based on IPv6'') latif at
Tue Jul 31 22:23:04 SAST 2012



I guess you have made the case for the remaining address space (especially
PIs) or at least a good portion of it should mandate v6 transition or at
least a short term commitment .


This is in no way a policy recommendation but universities will be play a
major role in reassuring governments and industry that v6 can be turned on
(not live J)  with some skills that universities will share due to their
academic freedom to disseminate strategic best practices.


I will get back to you with a success story piece with a bit more details
though it must be exhausting to write this stuff down.





From: afripv6-discuss-bounces at
[mailto:afripv6-discuss-bounces at] On Behalf Of Andrew Alston
Sent: mardi 31 juillet 2012 21:55
To: IPv6 in Africa
Subject: Re: [afripv6-discuss] IPv6 rollout


Hi Guys,


Ok a bit more info now that I have time to sit down and write, sorry things
have been rather hectic.


Here is how this came about, and a bit more of the full story.


The university in question was running a network without a real topology, in
essence, it was a flat network, v4 only, and a massive one at that.  This
was causing REAL issues, and it was the result of years and years of legacy.
The decision was taken that IPv6 would be required, but, simply put, we had
to fix the network first.  So first step, how do you migrate from a flat
network running a single /16 flat, to a segmented network, and do it on a
live campus environment that has 38 thousand users on it every day using the
network?  The answer... very very carefully, with a lot of planning, and
some very careful segment and IP planning.


So, the following decisions were made:


A.) We get rid of NAT in entirety - if we were going to do this, we would do
it properly, and the dual stack would be on live IPs in identical topology
v4 and v6 network wide.  

B.) We divide the network into a three tier network, core, distribution and

C.) Core/Distribution would be routed, would have to be scalable, and we'd
use SP style protocols to do this.

D.) Edge would remain layer 2, but we would choose not to span any L2 across
distributions.  Since Core/Distribution in future will be MPLS enabled, if
we need L2 between to points, we can EoMPLS it.


So we did our planning, and discovered (to our horror), that changing the
topology, eliminating NAT, and rolling out the wireless infrastructure we
had planned, we'd need a LOT more IPv4 space.  So, we applied and were
granted a second /15 PI space from AfriNIC.   We then started


First step:  Pick a network segment - we chose the student residences (not
because we hate the students, but because we wouldn't break any critical
research if it all went horribly wrong).  Then, we moved all the student
residences between a single distribution, our residence distribution.  At
this point, Vlan 1 was still spanned to the residence distribution, so
NOTHING had broken in doing this, all was working.  Then, we created a point
to point link between that distribution and the core.  On the point to
point, we put a /30 v4 and a /126 v6.  (Sadly, the gear we are using doesn't
support either /31 or /127).


Then, we enabled ospf for v4 and ospf3 for v6 across the point to point.
There is a slight difference in the topologies at this point because the
ospf for v4 was configured to ONLY carry the point to point and the
loopbacks from the distributions, the rest is covered by iBGP, where as in
v6, the hardware didn't do ipv6 bgp, so we had to do full route distribution
of v6 in OSPF3.  


Note at this point, we had still had zero downtime.


Then, for each residence between the distribution, we created a vlan, and
assigned it an IP segment and an IPv6 segment.  To avoid mass routes in our
routing tables, these segments were all taken out of supernets we had
dedicated to each distribution, and the supernets were what we pushed into
the routing table on both v4 and v6 level.  So, the vlans were now created
on the distribution, the routing was working.  Fixed up the DHCP for v4 as
well, so that was in place and ready to go with the correct scopes.  (Note,
we are using RA for v6 at this point, we haven't gotten around to DHCPv6
yet, so most people are still hitting the DNS servers on v4 addresses, since
we can't push DNS via RA).   


Note: Still ZERO downtime to anyone


Then, we took the created vlan's on the distribution, trunked them down to
the edge switches, waited till after hours, and moved the edge ports into
the correct vlan's.  (Different vlans for student pcs and wireless aps etc).
The actual move into the correct vlans was like, a single command on each
switch.  Then simple forced a port flap one very port as we went.  The port
flap was to force a DHCP reallocation on v4.


Bang, the residences came up on the new topology with v4 and v6 - total
downtime to the clients - less than 30 seconds.


Then, we did a rinse and repeat job through the various distributions (we're
still busy doing some of them, 6 outta 11 done so far, and probably around
300 or 400 edge switches tagged correctly).


Once we were sure the topology was working, and the IPv6 was working, next
step was to enable the ipv6 on the proxy servers, so that they could fetch
via IPv6.  We did this, and instantly saw around 30% of the traffic coming
in via v6, primarily google, youtube, facebook and akamai.  Note however, at
this point the clients were still seeing the proxies via v4, though the
proxies were fetching via v6.  So next step, put in quad-a records for the
proxy servers and for the pac file round robin.  Suddenly, everyone who had
a v6 address was fetching from the proxy servers via v6, irrespective of if
the proxies were fetching v4 or v6.


Suddenly, we had a situation where 50% of the traffic coming in was via
IPv6, and we infact peaked at well over 100mbit of IPv6 traffic today coming
in off the Internet.  


Our next steps of course are to migrate the rest of the distributions and
edge to the new network, and infact in the next 10 minutes we'll be moving
another thousand edge ports into this.  Once this is done, we'll start
looking closely at the server infrastructure and how we go about putting the
rest of the production servers both into the new topology and IPv6 enabling
them.  We expect this to be the most problematic part, since we know there
are certain services which have issues with IPv6, but we'll work around
those when we get there.


In summary - it is entirely possible to take a network with around 15
thousand wired network points, a few hundred wireless access points, a few
thousand VOIP phones and completely redeploy it both on a v4 and a v6 level
with almost no downtime if the planning is correct.  The traffic levels also
prove, there is IPv6 content out there, lots of it, and we're happy to use
it!  It just takes some planning, some forethought and some people willing
to work really hard at strange hours getting it done.


For interests sake, graphs can be seen here:
group=TSN81> &selectedmnemonicgroup=TSN81


The graph marked vl1081 is the IPv4 interface to TENET (The South African
NREN), the graph marked vl3081 is the IPv4 interface to TENET.  We
specifically asked them to provide v4 and v6 on separate interfaces as it
did allow for us to see the traffic on a more individual basis as well,
which was useful.


Hope this answers some of the questions I have been sent off list and
provides hope for those who believe that IPv6 migration is impossible -
never forget - we did it on both v4 and v6 *at the same time*, on a live
network, with no downtime, so if anyone doubts it can be done, we're proof
that it can.




Andrew Alston

Network Consultant


NOTE: I write the above as a private individual and private consultant and
have gained specific permission from my client (The University of the Free
State) to relay this story.  I would like to say a special thank you to them
for allowing me to share this with you as well.



On 31 Jul 2012, at 3:58 PM, Maye diop <mayediop at> wrote:

Dear Andrew,
I look forward more details to share with my universities.
Best Regards.
Le 31 juil. 2012 07:11, "Andrew Alston" <alston.networks at> a écrit
> Hi Guys,
> So, while i'll be sending out a lot more data soon, with a lot more
information on exactly what we did and how we did it etc, I thought  I would
share some news that I for one found rather exciting.
> Yesterday evening starting at around 7pm one of the South African
universities turned up IPv6, in a fairly consistent manner.  Now, I'm not
talking about turning up IPv6 on a few servers, I'm talking about
integrating it into every part of their network.  By 2:30am this morning it
was running on all their proxy servers, all their residence networks, the
wireless networks, all the lab PC's and a good portion of the staff network.
The topology used was identical to that of the IPv4, and as the rest of the
network is migrated to the new IPv4 topology V6 will be implemented on
everything in dual stack along side that as well.
> Now, here is where things get interesting, another network dual stacked is
no real news, so lets talk about traffic levels.
> The University in question is now running anywhere between 30 to 50
percent of its internet traffic on IPv6, and its working flawlessly so far.
So flawlessly infact that even with Apple's default implementation of Happy
Eyeballs that tests RTT and defaults to v4 if the v6 latency is higher, the
apples we tested on running lion and mountain lion were still choosing ipv6
most of the time.
> I am not going to say this little rollout has been easy though, we had to
rearchitecture the entire network (that had to happen anyway for various
reasons), and we added the v6 as part of that project.  It would not have
been possible to do that without first getting our hands on another /15
worth of IPv4 space though to allow that rearchitecturing to happen
> As I said though, in coming days we'll write up what we did with a lot
more detail and send through some graphs and other information, I just had
to share the fact that we're seeing at points half the traffic on a standard
university coming in from the internet over ipv6!
> Thanks
> Andrew Alston
> Network Consultant_______________________________________________
> afripv6-discuss mailing list
> afripv6-discuss at

afripv6-discuss mailing list
afripv6-discuss at


-------------- next part --------------
An HTML attachment was scrubbed...

More information about the afripv6-discuss mailing list