IDR Working Group Y. Joo Internet-Draft E. Hwang Intended status: Informational Y. Kim Expires: April 21, 2011 Korea Internet & Security Agency of Korea S. Baek Korea Internet Neutral eXchange October 18, 2010 4-octet AS number application scenario for stable network operation draft-joo-idr-fouras-application-scenario-00.txt Abstract This document is designed to help organizations in their use of 4- octet AS numbers in the future by checking the possibility of interaction between 2-octet AS numbers and 4-octet AS numbers for each scenario, based on the compatibility of heterogeneous equipment used in the actual network related to 4-octet AS numbers, and by verifying the interoperability of networks specified in each scenario - before using 4-octet AS numbers, before applying 4-octet AS numbers, as well as the influence on service traffic at the time of interaction. Status of this Memo This Internet-Draft is submitted to IETF in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet- Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on April 21, 2011. Copyright Notice Copyright (c) 2010 IETF Trust and the persons identified as the Joo, et al. Expires April 21, 2011 [Page 1] Internet-Draft 4-octet AS number application scenario October 2010 document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . .2 2. Definition of terms . . . . . . . . . . . . . . . . . . . . . .2 3. Use and composition of 4-octet AS numbers . . . . . . . . . . .2 4. 4-octet AS number applications. . . . . . . . . . . . . . . . .3 4.1. 4-octet AS number application scenario . . . . . . . . . .3 4.2. 2-octet <-> 4-octet <-> 2-octet link . . . . . . . . . . . 4 4.3. 4-octet <-> 2-octet <-> 4-octet link . . . . . . . . . . . 5 5. Additional items to consider for 4-octet application. . . . . .5 5.1. If OLD speaker exists in the iBGP segment within a 4-octet AS number. . . . . . . . . . . . .5 5.2. Equipment load amount measurement in line with 4-octet AS number use. . . . . . . . . . . . .6 5.3. Verification of 4-octet AS number applications in the IPv6 environment. . . . . . . . . . . .7 6. Conclusion. . . . . . . . . . . . . . . . . . . . . . . . . . 8 7. Acknowledgements. . . . . . . . . . . . . . . . . . . . . . . 9 8. Normative References. . . . . . . . . . . . . . . . . . . . . 9 9. Informative References. . . . . . . . . . . . . . . . . . . . 9 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10 Joo, et al. Expires April 21, 2011 [Page 2] Internet-Draft 4-octet AS number application scenario October 2010 1. Introduction AS numbers that are currently in use are based on the 2-octet system, and this is expected to become exhausted in the near future, like the IPv4 address system. 4-octet AS numbers are designed as an extension to 2-octet AS numbers, and the number of AS numbers available for allocation is increased by 65,000 times to cope with AS number exhaustion. A shortage is not likely in the short term, but long-term supply may be problematic. This document is designed to help organizations in their use of 4- octet AS numbers in the future by checking the possibility of interaction between 2-octet AS numbers and 4-octet AS numbers for each scenario, based on the compatibility of heterogeneous equipment used in the actual network related to 4-octet AS numbers, and by verifying the interoperability of networks specified in each scenario - before using 4-octet AS numbers, before applying 4-octet AS numbers, as well as the influence on service traffic at the time of interaction. 2. Definition of terms - New Speaker: BGP router that supports RFC4893 and 4-octet or 2-octet configuration (in other words, OS upgraded router) - Old Speaker : BGP router that cannot support RFC4893, and supports 2-octet configuration only (in other words, OS non-upgraded router) 3. Use and composition of 4-octet AS numbers - "AS TRANS#23456" was newly reserved for interoperability between 4-octet AS number capable speakers and non 4-octet capable BGP speakers. - Mechanisms that build up AS PATH information using AS_PATH and AS4_PATH were implemented. - Mapping at AS_PATH using the reserved AS23456 is used. - ISP allocated with new 4-octet AS numbers can configure a complete AS Path because these numbers are compatible with 2-octet numbers. - ISPs that once used allocated 2-octet numbers can link with the Joo, et al. Expires April 21, 2011 [Page 3] Internet-Draft 4-octet AS number application scenario October 2010 ISPs newly allocated with 4-octet AS numbers. - However, 4-octet AS numbers (e.g., AS65536(1.0)) are not accurately recognized, but recognized as the reserved "AS23456" - ISPs allocated with 2-octet AS numbers can link with 4-octet AS numbers without the need for an OS upgrade. - ISPs can upgrade the OS and replace the equipment gradually, in order to introduce the route that can recognize 4-octet numbers. 4. 4-octet AS number applications 4.1 4-octet AS number application scenario The heterogeneous environment using 2-octet AS numbers was configured, and this was similar to the actual network configuration. Then, a linkage with 4-octet AS numbers in the network was applied, and the scenario to the service traffic test was performed over stages. ======== ============= AS64496 ------------------AS64497 ======== ============= | | ============= =============== AS65550(1.14) ------- AS65551(1.15) (iBGP congruation) ============== ================ [Figure 1] The command used to apply 4-octet AS numbers to the equipment is different for each manufacturer. The router used for the scenario only accept the ASDOT setting, because only the OS that supports ASDOT type 4-octet AS was released. Equipment belonging to each AS number shown in Figure 1 performs the full-mesh type interface among all AS numbers, before configuring and unfolding the scenario. A total of three peers were established - AS64497, which is the remainder of AS64496 excluding itself, and 131100 and 131101 - 4- octet AS numbers. However, it was found that two 4-octet AS numbers were recognized as AS23456, as there was an OLD speaker that could not recognize 4-octet AS numbers at all. Joo, et al. Expires April 21, 2011 [Page 4] Internet-Draft 4-octet AS number application scenario October 2010 AS65550(1.14) was a NEW speaker set with 4-octet AS numbers. It was found that AS65550(1.14) exchanges AS-PATH with the peer expressed by 4-octet AS numbers between heterogeneous equipment in the interface information and routing table. The routing table information that transits the network in question was clearly expressed, as the interface was established with two 2- octet AS numbers excluding 2.28 (131100) - own AS number, and one 4- octet AS number - 2.29 (131101). In addition, equipment that is a NEW speaker assigned with 4-octet AS numbers and linked by iBGP, instead of a border router, has only one optimal set of path information, not the multiple path information recognized as 4-octet AS numbers. Regardless of the 4-octet expression method - ASDOT or ASPLAIN, it is recognized and expressed by local equipment only, and could not affect the interface work or routing table exchange at all 4.2 2-octet <-> 4-octet <-> 2-octet link This test is designed for cases in which heterogeneous equipment is configured in such a way that the service traffic path passes through the border area of 2-octet numbers and 4-octet numbers several times. The test was designed to check how traffic generated in a 2-octet AS number network affects service quality if it is sent to the 2-octet AS number network via the 4-octet AS number network. The test was made in the configuration shown in Figure 2. ======= ============= AS64496 ------------------AS64497 ======== ============= | | | | | ============= | |------ AS65551(1.15) ---| ============== [Figure 2] The test result shows that traffic is sent from the PC connected to AS64496 to the FTP server connected to AS64497 via AS65551(1.15) It was found that traffic arrived at the destination. Joo, et al. Expires April 21, 2011 [Page 5] Internet-Draft 4-octet AS number application scenario October 2010 4.3 4-octet <-> 2-octet <-> 4-octet link Among various test cases in which the service traffic path passes through the border area of 2-octet numbers and 4-octet numbers several times, this test was designed to check how traffic generated in a 4-octet AS number network affects service quality if it is sent to the 4-octet AS number network via the 2-octet AS number network. The test was made in the configuration shown in Figure 3. ============= | ------------------ AS64497 | ============= | | ============= ================== AS65550(1.14) ------- AS65551(1.15) (iBGP congruation) ============== ================== [Figure 3] The above figure shows the trace route result that traffic is traced from the PC connected to AS65551(1.15) to the FTP server connected to AS65550(1.14) via AS64497. The file was sent to the FTP server connected to AS65551(1.15) from the PC connected to AS65550(1.14) via AS64497, which clearly indicated that traffic was sent reverse. 5. Additional items to consider for 4-octet AS number 5.1 If OLD speaker exists in the iBGP segment within a 4-octet AS number =============== AS65551(1.15) (iBGP congruation) ================ There was a problem wherein the same AS number cannot be set for the OLD speaker in the iBGP segment, as 4-octet AS numbers are not supported. It was checked as to whether AS23456 could be used in the iBGP segment, because it cannot be used according to the 4-octet AS number Joo, et al. Expires April 21, 2011 [Page 6] Internet-Draft 4-octet AS number application scenario October 2010 standard, as it is a reserved AS number. As AS23456 is used to interface with 4-octet AS numbers in OLD speaker, Local-AS of the OLD speaker was set to 23456, but the interface itself failed. To make another attempt, Local-AS of the OLD speaker was set to the private AS number for testing. In conclusion, it is recommended to exclude the OLD speaker (equipment not recognizing 4-octet AS numbers) from the iBGP segment in the 4-octet AS number. On the other hand, if the 4-octet AS number network is used, the border router is supposed to be composed of equipment that can basically recognize and run 4-octet AS numbers. Therefore, this network can operate regardless of the counterpart peer's status - use of 2-octet AS numbers or 4-octet AS numbers. However, problems may be presented if any internal equipment that interfaces with iBGP cannot recognize 4-octet AS numbers. Basically, this kind of equipment should use 2-octet AS numbers (because 4-octet AS numbers cannot be used), and iBGP interface cannot be established with 4-octet AS numbers. In conclusion, the 2-octet private AS number should be used. (According to the test results, interface with 4-octet AS numbers was not established if set to AS23456.) This implies that the network does not use a single AS number. In summary, if the network uses 2-octet AS numbers, equipment does not need to recognize 4-octet AS numbers. (However, it is recommended to upgrade the border router that recognizes 4-octet AS numbers for the purpose of routing policy flexibility.) If the network uses 4-octet AS numbers, the network would run stably only when all equipment to be installed with the BGP is upgraded. 5.2 Equipment load amount measurement in line with 4-octet AS number use For proper comparison, this test compared the same equipment and memory use amounts. Joo, et al. Expires April 21, 2011 [Page 7] Internet-Draft 4-octet AS number application scenario October 2010 ============================================================ Applied AS number | 13110(4-octet) | AS64497(2-octet) ------------------------------------------------------------ Memory use amount(bit) | 33,949,910 | 29,239,556 ------------------------------------------------------------ Number of neighbors | 3 | 3 ------------------------------------------------------------ Number of prefixes | 10 | 10 ============================================================ [Figure 4] As shown in Figure 4, there was approximately a 16% difference in the rate of use, even though the same number of peers and network tables is managed (received 9, connected 1, best 4). As this difference can become larger with an increase of interfacing neighbors and managing network tables, it would be more stable for equipment using 4-octet AS numbers to secure sufficient memory. Of course, the equipment's memory use amount can differ depending on the OS version installed in the equipment, as the AS_PATH information in 4-octet AS numbers uses data size two times more than that of 2- octet AS numbers, due to the number configuration system. In theory, the memory use amount of 4-octet AS_PATH requires two times as much memory as 2-octet AS_PATH. 5.3 Verification of 4-octet AS number applications in the IPv6 environment With the anticipation that the future IP environment will gradually transit to an IPv6 environment, it was verified whether 4-octet AS numbers to be newly applied can be interfaced in the IPv6 environment just like in the IPv4 environment. For interface compatibility in the AS number environment composed of heterogeneous equipment, the BGP serial IP and announce network were defined with IPv6, as shown in Figure 5. The verification was designed to determine if there were any problems in the interaction between 2-octet AS numbers and 4-octet AS numbers in the IPv6 environment. To apply the IPv6 address, the IPv6 routing option should be enabled (activated) in each equipment item for BGP interface with IPv6. ========= =============== AS64496 -------- AS65551(1.15) ========= =============== [Figure 5] Joo, et al. Expires April 21, 2011 [Page 8] Internet-Draft 4-octet AS number application scenario October 2010 It was found that interaction with 4-octet AS numbers in the IPv6 environment is not an obstacle at all, according to the results of verifying the BGP neighbor status and routing table exchange after completing the settings. 6. Conclusion The result of the interaction between 4-octet AS numbers and 2-octet AS numbers shows that the NEW speaker, which supports 4-octet AS numbers, can apply 4-octet AS numbers just like BGP declaration in the existing environment. The only difference is that the declared AS number is 32 bits (4 bytes) in size, instead of 16 bits (2 bytes). In addition, the interface between the network applied with 4-octet AS numbers and the one applied with 2-octet AS numbers can be established without difficulty using the agreed AS number "AS23456". However, the OLD speaker that recognizes 2-octet AS numbers only cannot separate networks uniquely and establish a routing policy, while the AS23456 network size grows as the number of 4-octet AS number networks increases. Therefore, it is necessary to plan OS and hardware upgrades so that OLD speaker systems can recognize 4-octet AS numbers. This is in order to cope with the full-scale use of 4-octet AS numbers and the corresponding increase in the number of networks. The test result indicated that 4-octet AS number interaction is not affected by the IP environment - IPv4 or IPv6. Theoretically, the interface using 4-octet AS numbers should not cause large differences in speed, because the data service is affected by the packet forwarding capability of the transit equipment, although first peering establishment and routing table updating could take more time than those using 2-octet AS numbers. Considering that speed is not dropped in proportion to the number of 4-octet AS number transit points, the test in more diverse environments should use 4-octet AS numbers, instead of conducting a simple test. Joo, et al. Expires April 21, 2011 [Page 9] Internet-Draft 4-octet AS number application scenario October 2010 7. Acknowledgements The authors would like to thank Baek Seong-hyeok who built and tested a test bed for 4-octet AS number application, as well as many supporters who helped in drawing useful conclusions, including Joo Yongwan, Kim Yunjeong, Yoo Jiyeol, Lim Junhyeong, Baek Hyeongjong, Lee Jiyeong, Kim Seohui, Park Hyeonseung, Choi Yunmi, Yang Yeongha, Jeon Jiyeong, Kim Yunsog, and Kim Hyeongjun. In addition, we would like to appreciate the RFC authors through this paper for their useful guidelines to 4-octet AS support. 8. Normative References [BGP] Rekhter, Y., Li, T., and Hares, S., "A Border Gateway Protocol 4(BGP-4)", RFC 4271, January 2006. [RFC4893] Q. Vohra, E. Chen, "BGP Support for Four-octet AS number Space", RFC 4893, May 2007. [RFC5396] G. Huston, G.Michaelson, "Textual Representation of Autonomous (AS) Numbers", RFC 5396, December 2008. 9. Informative References [AS-EXT-COM] Rekhter, Y., Ramachandra, S., and Tappan, D. "Four- octet AS Specific BGP Extended Community", draft- rekhter-as4octet [RFC1997] Chandra, R., Traina, P., and T., Li., "BGP Communities Attribute", RFC 1997, August 1996. [RFC3392] Chandra, R. and J. Scudder, "Capabilities Advertisement with BGP-4", RFC3392, November 2002. [RFC3065] Traina, P., McPherson, D., and J. Scudder, "Autonomous System Confederations for BGP", RFC3065, February 2001. Joo, et al. Expires April 21, 2011 [Page 10] Internet-Draft 4-octet AS number application scenario October 2010 Authors' Addresses Joo Yong-wan Korea Internet & Security Agency of Korea 11F 398 Seochoro Seocho-gu Seoul, 137-857 Korea Email: ywju@kisa.or.kr Hwang Eui-jong Korea Internet & Security Agency of Korea 11F 398 Seochoro Seocho-gu Seoul, 137-857 Korea Email: hej@kisa.or.kr Baek Seong-hyeok KINX Dogok-dong, Gangnam-gu Seoul, 137-857 Korea Email: shbaek@kinx.net Kim Yoon-jeong Korea Internet & Security Agency of Korea 3F 398 Seochoro Seocho-gu Seoul, 137-857 Korea Email: kyoonj@kisa.or.kr Joo, et al. Expires April 21, 2011 [Page 11]