IPv6 Evolution, Stability and Deployment

2011 19th IEEE International Conference on Network Protocols
IPv6 Evolution, Stability and Deployment
Xiaoke Jiang ⋆ , Jun Bi † , Yangyang Wang ⋆ , Zhijie He ⋆ , Wei Zhang ⋆ , Hongchen Tian ⋆
{ ⋆ Dept. of Computer Science, † Network Research Center}, Tsinghua University, Beijing, 100084, P.R.C
Email: ⋆ {justok, wyy, hzj, zw, tianhc}@netarchlab.tsinghua.edu.cn, † junbi@tsinghua.edu.cn
Abstract—Our subject focuses on IPv6 network, which develops
for more than 10 years. How IPv6 evolve in those years? Is
IPv6 network mature enough to undertake the load produced by
users? Can we find some principles to guide IPv6 deployment,
which make the whole network more robust and efficiency?
This paper tries to answer these questions with in-depth
statistics. Good news is that network is growing at a speed of
O(d 2 ) (d is time) after 2006, moreover, network itself and its
routing system become more and more stable. And we explore
special properties of this preliminary network, We find that
distribution of AS degree follows "Power-Law Distribution", but
AS-level topology cannot be described as "Small-World Model"
properly. We also propose a method to define the importance
of AS and give a simple principle of IPv6 deployment. We even
build "6Stats Project"[1] to provide data which help deploy IPv6.
Index Terms—IPv6, Routing, Deployment, Network Measurement
I. INTRODUCTION
IPv6 experienced a slow development for a long time since
1999, but now it goes into a rapid growth stage, which is
different from IPv4[4].
But most of research on IPv6 uses a poor dataset, which may
be small or outdated. What’s more, most of existing research
follows what we have done on IPv4. As a newborn technology,
the special properties haven’t get enough attention. So we
calculate a lot of indexes to show its tomography, based on
which we study on principles of IPv6 deployment using graph
theory.
In this paper, we use whole IPv6 BGP RIB data collect by
RouteViews Project from May 3/2003 to Oct 31/2010, Taking
account of limitation of monitors and this methodology itself,
we mostly calculate one index result instance using data of
whole month.
II. EVOLUTION
A. Growing at a Speed of O(d 2 )
Fig 1a gives amount of prefixes, ASes, links. If "d" represents
time gap between statistics date and starting date,
network grew with the speed of O(d) before 2006[3], And
after [4] argues the speed is O(e d ). But we suppose O(d 2 ) is
more accurate.
We draw asymptotic lines of those results between Jan/2006
and Oct/2010 with quadratic polynomial and exponential. For
link line(Highest, Green),
y = 0.0025x 2 − 196.36x + 10 6 (R 2 = 0.9927)
is better than y = 3×10 −11 e 0.0008x (R 2 = 0.9445) , for 0.99
is bigger than 0.94. As to AS(Lowest, Red) and prefix line, we
8000
7000
6000
5000
4000
3000
2000
1000
AS#
Link#
Prefix#
0
2003 2004 2005 2006 2007 2008 2009 2010 2011
(a) Amount of Entities
35
30
25
20
15
10
Prefix
PATH axes x1y1
Coef.(y2 axis)
5
2003 2004 2005 2006 2007 2008 2009 2010 2011 0.11
(b) Avg Life, Cluster Coef
Fig. 1: Evolution of IPv6 Network
get similar result. So O(d 2 ) is better than O(e d ) to describe
network size. This matches people’s intuition: changing from
O(d) to O(d 2 ) is smoother than to O(e d ).
B. Special Properties of Preliminary Network
According to our statistics, amount of IPv6 prefix and ASes
is just 1% of those of IPv4, we suppose IPv6 is not ready to
undertake all the traffic people produce daily.
And we also measure the average AS_PATH length from
monitors to other AS. We find an abnormal phenomenon.
Small-World Model infer that length increase slowly while
amount of node increase, which is positive correlation. But
from 2003 to 2010, amount of AS increase(Fig 1a) while
average length decrease! Fig 3a shows this trend 1 . That is
negative correlation. So Small-World Model cannot describe
IPv6 AS-level topology. But Log-log CCDF line in Fig 3b is
nearly liner, which proves that AS degree meets Power-Law
Distribution.
We suppose the phenomenon is result of small ASes and
links set, which leading to no "shortcuts" for packet forwarding
between AS pairs. So packet has to follow a long path
without choice.
A. Key Indexes
III. STABILITY OF IPV6 NETWORK
Fig 1b shows average prefix life, path life and cluster
coefficient in one month. Life here means appearing days per
months. Path life obviously becomes longer. Upper bound of
prefix life doesn’t change clearly, but lower bound increases.
As for cluster coefficient, it shook more fiercely before 2006
than after that.
1 here path is AS_PATH from other ASes to RouteViews monitors. So result
here is not average path length of whole network, but it does show the trend.
0.17
0.16
0.15
0.14
0.13
0.12
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1
5.8
5.6
5.4
5.2
5
4.8
4.6
4.4
3.5
3
2.5
2
1.5
month
week
day
2003 2004 2005 2006 2007 2008 2009 2010 2011
Fig. 2: Path# for AS Pair in one Month/Week/Day
Average Length of AS PATH
1
0.9
0.8
0.7
0.6
1 10 100 1000
1
CDF
Log-Log CCDF (x2-y2)
0.1
0.01
similar index, clustering coefficient[2] (short as coef in the
following), which reflects node trend of clustering, or "friends
of friends".
Pick 3 types of ASes first: ASes with most neighbors,
biggest local coef and smallest local coef, excluding coef equal
0 or 1 in order to clear effect of single link and small total joint
group. Then recalculate average coef after removing AS in the
picked list one by one. We find that removal of ASes with
most neighbors cause greatest effect on the new average coef.
This proves that kind of ASes own more important position
in AS-level topology, for they contribute more to network
performance.
So we suppose that there does exist strategies which help to
increase the robust and efficient of network when deploy IPv6.
For example, connecting to AS "important" neighbors, which
leads average path to other ASes short and that AS forwarding
efficiency(but the whole network forwards may not be the most
efficiency). And other deeply strategies can be explored.
4.2
4
3.8
2003 2004 2005 2006 2007 2008 2009 2010 2011
(a) average path length
0.5
0.4
0 100 200 300 400 500 600 700 800 900 0.001
(b) AS Degree CDF and log-log CCDF
Fig. 3: Special Phenomenons
We also analyze appearance and disappearance of path, links
and AS, prefix length and origin AS of prefix, all indexes show
trend of becoming stable. In particular, status after 2006 is
more stable than before that, Fig 3a is an evidence.
B. Instability of Routing System
There are 3 lines in Fig 2, which represent average amount
of paths for AS pairs(Source AS and destination AS) calculated
in different intervals: Month, Week and Day. The value
decreases over time, especially the month line, decreasing from
3 in 2003 to 1.5 in 2010.
We also explore the similarities of set of AS, path and links
between sequential months, and the similarities increase over
time. All those prove that network itself and its routing system
are becoming stable. And year 2006 is prove to be milestone
of stability, too.
A. Environment Faced
IV. DISCUSSION OF DEPLOYMENT
Fig 3b is AS degree CDF and log-log CCDF graph 2 , which
shows the environment ISP facing to deploy IPv6. 44% of
ASes only have one degree. CDF grows very fast at start-up,
more than 80% of ASes have degree small than 6. It grows
very slow at later stage, less than 8% of ASes have degree
more than 16, but maximal degree is more than 800.
B. Importance of AS
We suppose that the best way to measure importance of
AS is its impact to the average shortest path length, but this
is really hard under the circumstance of complicated BGP
configuration and business relationship. So we pick another
2 Based on data in Mar/2010, others show similar properties
V. CONCLUSIONS
In this paper, our conclusions include:
• Scale of IPv6, growing at a speed of O(d 2 ), not O(e d )
as some paper argues. Growing doesn’t follow Moore’s Law,
but does go into rapid spread stage.
• IPv6 network itself and its Routing System are becoming
more and more stable.
• Year 2006 is a milestone of network. After 2006, network
is more mature and stable and develops faster. We suppose
the reason is that network change gradually from a scientific
research network to production network, for example, applications
of CNGI-CERNET2 in China, IPv6 site of Google and
IPv6 commercial service of Comcast.
• AS-level topology cannot described as Small-World
method, which reflects properties of its preliminary stage.
• AS with more neighbors take more importance position
in the topology. Connecting with importance AS is a good
strategy of establishing new link, which should get special care
when nearly half of ASes access the Internet by single Link.
And our future work will explore more special properties, a
more accurate model to define importance of AS and give
more deeply principles to guide IPv6 deployment.
VI. ACKNOWLEDGMENTS
Supported by National Science Foundation of China under
Grant 61073172. Program for New Century Excellent
Talents in University. Specialized Research Fund for the
Doctoral Program of Higher Education of China under Grant
200800030034,
REFERENCES
[1] 6Stats Project. http://202.112.49.243/Web6/index/.
[2] Cluster Coefficient. http://en.wikipedia.org/wiki/Clustering_coefficient.
[3] W. Eddy. Basic properties of the ipv6 as-level topology. ACM SIGMET-
RICS Performance Evaluation Review, 36(3):50–57, 2008.
[4] G. Zhang, B. Quoitin, and S. Zhou. Phase changes in the evolution of
the ipv4 and ipv6 as-level internet topologies. Computer Comunications
(COMCOM), 34(5):649–657, 2011.
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