1. Investigating the Prefix-level Characteristics A Case Study in an IPv6 Network Department of Computer Science and Information Engineering, National Cheng Kung University, Tainan, Taiwan, R.O.C. Authors:Fuliang Li, Tian Pan, Jiahai Yang, Changqing An, Xingwei Wang, Jianping Wu. Publisher:2015 International Conference on Computing, Networking and Communication (ICNC) Presenter:Chun-Yu, Li Date:2015/10/14

2. Outline Introduction Exhausting of IPv4 Main Investigation Studied Network and Datasets Assignment and Activity of IPv6 Prefixes Prefix Assignment Prefix Activity Prefix-level Characteristic of CERNET2 Prefix Activity Observed from Traffic Packet and Traffic Distribution across Prefixes Relationships among Address, Prefixes and Packets Prefixes Distribution across Different Timescales Computer & Internet Architecture Lab CSIE NCKU 2

3. Exhausting of IPv4 (1/1) Internet Assigned Numbers Authority (IANA) announced in February 2011 that the last of the world’s remaining IPv4 blocks had been assigned to the Regional Internet Registries (RIR). On April 15, 2011 the Asia Pacific Region claimed it has reached the last block of IPv4 addresses in its available pool. As IPv6 has much larger address space than IPv4, understanding the characteristics of IPv6 prefixes is of great benefit to guide the efficient IPv6 routing cache design. Computer & Internet Architecture Lab CSIE NCKU 3

4. Outline Introduction Exhausting of IPv4 Main Investigation Studied Network and Datasets Assignment and Activity of IPv6 Prefixes Prefix Assignment Prefix Activity Prefix-level Characteristic of CERNET2 Prefix Activity Observed from Traffic Packet and Traffic Distribution across Prefixes Relationships among Address, Prefixes and Packets Prefixes Distribution across Different Timescales Computer & Internet Architecture Lab CSIE NCKU 4

5. Main Investigation (1/1) We launch a full-scale statistics of IPv6 prefixes from two aspects, i.e., assignment and activity. We analyze the prefix-level characteristics based on the traces of an IPv6 network. We conduct a case study on prefix related characteristics in an IPv6 network. Computer & Internet Architecture Lab CSIE NCKU 5

6. Outline Introduction Exhausting of IPv4 Main Investigation Studied Network and Datasets Assignment and Activity of IPv6 Prefixes Prefix Assignment Prefix Activity Prefix-level Characteristic of CERNET2 Prefix Activity Observed from Traffic Packet and Traffic Distribution across Prefixes Relationships among Address, Prefixes and Packets Prefixes Distribution across Different Timescales Computer & Internet Architecture Lab CSIE NCKU 6

7. Studied Network and Datasets (1/2) The datasets are collected from the link connecting CERNET2 with CNGI-6IX. The bandwidth of the link is 10Gbps. Computer & Internet Architecture Lab CSIE NCKU 7

8. Studied Network and Datasets (2/2) CERNET2 It is a nation-wide pure IPv6 backbone network. It focuses on solving technical challenges during IPv6 deployment, overcoming difficulties in the operation and management of IPv6 networks. CNGI-6IX (China Next Generation Internet) CERNET2 interconnects to domestic CNGI backbones and international research networks through the exchange point of CNGI-6IX. Computer & Internet Architecture Lab CSIE NCKU 8

9. Outline Introduction Exhausting of IPv4 Main Investigation Studied Network and Datasets Assignment and Activity of IPv6 Prefixes Prefix Assignment Prefix Activity Prefix-level Characteristic of CERNET2 Prefix Activity Observed from Traffic Packet and Traffic Distribution across Prefixes Relationships among Address, Prefixes and Packets Prefixes Distribution across Different Timescales Computer & Internet Architecture Lab CSIE NCKU 9

10. Prefix Assignment (1/2) IPv6 prefixes allocated to the five RIRs (Regional Internet Registry) present obvious growth during 2011 – 2013. Computer & Internet Architecture Lab CSIE NCKU 10 75% 551% more coverage area

11. Prefix Assignment (2/2) We also find that prefixes of /32 account for 71% and 67.2% of the total assigned prefixes in 2011 and 2013 respectively, while the ratios are 19.1% and 20.4% for prefixes of /48. Computer & Internet Architecture Lab CSIE NCKU 11

12. Outline Introduction Exhausting of IPv4 Main Investigation Studied Network and Datasets Assignment and Activity of IPv6 Prefixes Prefix Assignment Prefix Activity Prefix-level Characteristic of CERNET2 Prefix Activity Observed from Traffic Packet and Traffic Distribution across Prefixes Relationships among Address, Prefixes and Packets Prefixes Distribution across Different Timescales Computer & Internet Architecture Lab CSIE NCKU 12

13. Prefix Activity (1/2) Computer & Internet Architecture Lab CSIE NCKU 13 We gather RIBs (Routing Information Base) from two observation points - CERNET2 on Nov 15, 2013 and University of Oregon Route Views project on Nov 20, 2013. Active prefixes in the closed interval of [32, 48] also account for most of the active prefixes (96.5% and 93.1% of the two observation points respectively).

14. Prefix Activity (2/2) The UPDs (BPG update messages) are collected from the border routers of CERNET2 in one-week scale. Only 56.13% of the total prefixes contribute UPDs. Prefixes whose lengths are within the range of [32, 48] contribute 96.5% of the total update messages. Prefixes in the closed interval of [32, 48] account for 97% of the total withdraw messages. 4103763 prefixes/day 47 prefixes/second Computer & Internet Architecture Lab CSIE NCKU 14 (One-week scale)

15. Outline Introduction Exhausting of IPv4 Main Investigation Studied Network and Datasets Assignment and Activity of IPv6 Prefixes Prefix Assignment Prefix Activity Prefix-level Characteristic of CERNET2 Prefix Activity Observed from Traffic Packet and Traffic Distribution across Prefixes Relationships among Address, Prefixes and Packets Prefixes Distribution across Different Timescales Computer & Internet Architecture Lab CSIE NCKU 15

16. Prefix Activity Observed from Traffic (1/1) Computer & Internet Architecture Lab CSIE NCKU 16 (Trace of CERNET2)

17. Outline Introduction Exhausting of IPv4 Main Investigation Studied Network and Datasets Assignment and Activity of IPv6 Prefixes Prefix Assignment Prefix Activity Prefix-level Characteristic of CERNET2 Prefix Activity Observed from Traffic Packet and Traffic Distribution across Prefixes Relationships among Address, Prefixes and Packets Prefixes Distribution across Different Timescales Computer & Internet Architecture Lab CSIE NCKU 17

18. Packet and Traffic Distribution across Prefixes (1/2) The most popular prefix in 2011 and 2013 is 2001:cc0::/32, which accounts for 81.4% and 61.4 % of the packets respectively. 1% of the active prefixes account for 98.14% of the packets in 2011, and 97.44% in 2013. 18 Computer & Internet Architecture Lab CSIE NCKU (Trace of CERNET2) 1% 98.14% 97.44%

19. Packet and Traffic Distribution across Prefixes (2/2) The most popular prefix in 2011 and 2013 is 2001:8000::/20, which contributes 86.78% and 61.72% of the aggregate traffic respectively. 1% of the active prefixes account for 98.39% of the traffic in 2011, while the proportion is 97.75% in 2013. 19 Computer & Internet Architecture Lab CSIE NCKU (Trace of CERNET2) 98.89% 97.44% 1%

20. Outline Introduction Exhausting of IPv4 Main Investigation Studied Network and Datasets Assignment and Activity of IPv6 Prefixes Prefix Assignment Prefix Activity Prefix-level Characteristic of CERNET2 Prefix Activity Observed from Traffic Packet and Traffic Distribution across Prefixes Relationships among Address, Prefixes and Packets Prefixes Distribution across Different Timescales Computer & Internet Architecture Lab CSIE NCKU 20

21. Relationships among Address, Prefixes and Packets (1/2) 1% of the active prefixes account for 60.6% and 71.9% of the addresses in 2011 and 2013. When the proportion of the active prefixes reaches 20%, the proportion of the active addresses is more than 90%. Computer & Internet Architecture Lab CSIE NCKU 21 71.9% 60.6% 1%

22. Relationships among Address, Prefixes and Packets (2/2) top 5% users account for 97.4% and 99.2% of the packets in 2011 and in 2013 respectively. According to the results, we can infer that a small part of users contribute most of the packets. Computer & Internet Architecture Lab CSIE NCKU 22 99.2% 5%

23. Outline Introduction Exhausting of IPv4 Main Investigation Studied Network and Datasets Assignment and Activity of IPv6 Prefixes Prefix Assignment Prefix Activity Prefix-level Characteristic of CERNET2 Prefix Activity Observed from Traffic Packet and Traffic Distribution across Prefixes Relationships among Address, Prefixes and Packets Prefixes Distribution across Different Timescales Computer & Internet Architecture Lab CSIE NCKU 23

24. Prefixes Distribution across Different Timescales (1/3) The variation of the active prefixes in a period are often used to estimate how large a cache will be needed to achieve a given miss rate. Computer & Internet Architecture Lab CSIE NCKU 24 (One minute time interval)

25. Prefixes Distribution across Different Timescales (2/3) The number of the changed prefixes is often used to estimate how often the cache should be updated. Computer & Internet Architecture Lab CSIE NCKU 25 (One minute time interval)

26. Prefixes Distribution across Different Timescales (3/3) Computer & Internet Architecture Lab CSIE NCKU 26 B 2011 (60)=342 B 2011 (30)=321 B 2011 (5)=264 If the update frequency of the routing system is higher, the buffer reserved for the worst-case burst updates could be even smaller. E.g., If the routing cache is updated once an hour and assume that there are no vanishing prefixes, we should reserve 5184 bytes (342*16 bytes).