1. Broadband Communication Lab. Asymmetric Path Detection in BGP Routing 29 January, 2004 Eun Mi, Park Korea Univ. Dept. of Electronics and Computer Engineering eun@widecomm.korea.ac.kr

2. Broadband Communication Lab. 2 KESG / APAN Contents Introduction Routing Area Goal System Architecture & Visualization system Data Analysis for BGP messages Asymmetric Paths In/out of KOREN Approaches in KESG Project Asymmetric Path Detection APD system Approach Issues

3. Broadband Communication Lab. 3 KESG / APAN Introduction Improving international link resource utilization Develop BGP analysis system to analyze and improve international link Collaborations with KOREN members, JP members

4. Broadband Communication Lab. 4 KESG / APAN Goal in BGP Routing Area 1 st Year Framework for improve international network performance & for detect abnormal routing information finding & collecting asymmetric paths BGP monitoring & visualization system 2 nd Year Detecting asymmetric paths Load balancing of the international links

5. Broadband Communication Lab. 5 KESG / APAN System Architecture (1) Seoul XP Busan XP BGPview Analyzer Visualizer DataBase 2 nd year major Measurement AreaBGP Routing Area

6. Broadband Communication Lab. 6 KESG / APAN System Architecture (2) Korea Pusan Taejon Seoul TO: APII link TEIN link H-G link BGPview Visualization Analysis system

7. Broadband Communication Lab. 7 KESG / APAN Brief Overview APAN-JP RENATER3 SINGAREN BGP View Web based interface DB Visualization system

8. Broadband Communication Lab. 8 KESG / APAN Implementing Visualization System The purpose is to report BGP table & update message status visually From modified BGPview agent Query from DB Real time report from BGPview User can see not only BGP status, but also full message format In abnormal state such as abnormal updates, user can see the routing entry to remove Message ID searching function Message information, message Prefix information, full message information

9. Broadband Communication Lab. 9 KESG / APAN Web based Visualization Total Message Information Prefix Information Full Information

10. Broadband Communication Lab. 10 KESG / APAN Data Structure for Visualization Field nameField TypeContents dateDateMessage date timeTimeExact time for message totallongTotal number of the message updatelongNumber of the updated message notificationlongNumber of the notification message openlongNumber of the OPEN message keepalivelongNumber of the KEEPALIVE message prefixlongNumber of the prefix in a receiving packet withdrawlongNumber of the withdraw message in a receiving packet

11. Broadband Communication Lab. 11 KESG / APAN Categorization PEERS neighbor : BGP router IP address remote_as : BGP router AS number local_as : default AS number holdtimer : for Hold timer adjust to manage the KEEPALIVE message MESSAGE_INFO For total message number ROUTER_TT For keep connection with the peer router DUMMYINFO To check BGPview ’ s condition ROUTE_INFO ROUTE_HISTORY

12. Broadband Communication Lab. 12 KESG / APAN Message Analysis

13. Broadband Communication Lab. 13 KESG / APAN Data Analysis All message is update message OPEN : WITHDRAW = 89% : 11% Only 1 OPEN message KEEPALIVE MESSAGE = (3msg./1min.) NO Notification Message About 12Mbyte/1day 7660(APAN-JP) 2200(RENATER3) 2523(APAN-JP) 7610(SingaREN) Entries in the International Links

14. Broadband Communication Lab. 14 KESG / APAN Asymmetric Paths KOREN User 1 User 2 User 3 JAPAN SingaREN TEIN Inside of the KOREN… Commercial Network?? Commercial Network?? Outside of the KOREN…

15. Broadband Communication Lab. 15 KESG / APAN APs in International Links KOREN AS9270 JAPAN AS7660 APII 8Mbps G-H 1Gbps #1 G-H 1Gbps #2 Others??? TO JAPAN

16. Broadband Communication Lab. 16 KESG / APAN APs in International Links KOREN AS9270 USA STARTAP HPCnet 45Mbps TransPAC 155Mbps * 2 Others??? TO USA

17. Broadband Communication Lab. 17 KESG / APAN Asymmetric Path Detection Basically, {traceroute} is the only to find exact asymmetric paths We can guess the APs by collecting routing information Match next hop, routing table If the path is outside of the KOREN By collecting routing table & BGP table IF the path is inside of the KOREN By PMI APD system For International Path International collaboration must be needed

18. Broadband Communication Lab. 18 KESG / APAN PMI Approach APDAgent APDServer 2. Interface IP list from each router 1. RSH “show ip aliases” 3. U ser selects APDAgent IP 7. S how result of APD 4. RSH“traceroute execute” 5. Store router interface IP and measured IP 6. S ends result which is compared

19. Broadband Communication Lab. 19 KESG / APAN Measurement Area Approach Netflow data based, inbound & outbound traffic analysis Make set of SRC AS Number of inbound traffic and DST AS Number of outbound traffic AS (in, seoul) = {AS1, AS2, … } AS (out, seoul) = {AS3, AS4, … } AS (in, daejeon) = {AS5, AS6, … } AS (out, daejeon) = {AS7, AS8, … } Ex. AS n ∈ AS (in,seoul) and AS n ∈ AS (out,daejeon) the path with AS n is asymmetirc

20. Broadband Communication Lab. 20 KESG / APAN APD System Approach All table must be gathered Seoul, Daejeon, Suwon, Kwangju … PMI system + measurement area data Implementing Matching function in Analyzer Analyzer will be added in modified BGPview system in 2 nd year Algorithm must be developed for address/AS PATH matching

21. Broadband Communication Lab. 21 KESG / APAN Conclusion After Asymmetric Path Detection, What is the Next? Asymmetric Paths are not abnormal … Basic Information for load balancing For International APD … Way to International collaboration

22. Broadband Communication Lab. Thank you