Network Working Group Jin Lizhong (ED) Internet Draft Feng Jun Expiration Date: Septembet 2007 ZTE Corporation March 2007 Inter-AS Pseudo Wire Extention draft-jin-pwe3-pw-inter-as-ext-00.txt Status of this Memo By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of 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. Abstract This document describes another way to set up a PW between two ASs in the scenario of directly connected ASBR between the two ASs. The Single-Segment PW or PW Segment of a MS-PW setup between two directly connected ASBRs dose not need PSN tunnel, so as to provide a more simple way to set up inter-as PW. In the scenario described Jin, et al. [Page 1] Internet Draft draft-jin-pwe3-pw-inter-as-ext-00.txt March 2007 in this draft, MP-EBGP can also be used to signal the mapping of PW, then no other protocols are existed between the two ASBRs. 1. Specification of Requirements The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119]. 2. Introduction In many network topology, the ASBRs between two different ASs are directly connected. The new way to set up inter-as PW described in this draft bases on this scenario. Figure 1 shows the scenario. In the MS-PW draft [I-D.draft-ietf-pwe3-segmented-pw-04] and [I-D. draft-ietf-pwe3-dynamic-ms-pw-02], if we want to set up a MS-PW across two different AS, then a PSN tunnel is needed between the two ASs or ASBRs according [RFC4447], whatever the ASBRs are directly connected. \ / AS1 | | AS2 ST-PE----S-PE1(ASBR1)---------S-PE2(ASBR2)----TT-PE | | / \ Figure 1: Inter-AS scenario The two S-PEs are at the same time ASBRs in Figure 1. ST-PE needs to set up a MS-PW to TT-PE, then a segment PW between S-PE1 and S-PE2 needs an PSN tunnel according the PW setup mechanism. An inter-as MPLS tunnel is needed according [RFC4447], maybe it is RSVP-TE tunnel or LDP tunnel. As we know, it is a little difficult to provide such a tunnel between two ASs, for the PE devices in the two ASs may not support the same type of inter-as tunnel. If the two S-PEs are not ASBRs or not directly connected, then an inter-as tunnel is a MUST; but if they are also ASBRs and directly connected, then the inter-as tunnel is not needed. It is more simple of not providing a PSN tunnel between the two ASBRs and no additional requirements are needed for the ASBRs. 3. PW without PSN tunnel If a Single-Segment PW or PW Segment of a MS-PW is setup between two directly connected ASBRs, then the PSN tunnel is not needed. In the MPLS label based network, the ASBR received PW packets from Jin, et al. [Page 2] Internet Draft draft-jin-pwe3-pw-inter-as-ext-00.txt March 2007 intra-as MPLS tunnel, pops the external label if PHP is disabled or explicit label is used, switches the PW label with the one sent by peer ASBR, then sends the packets to peer ASBR. The peer ASBR switches the PW label with the one sent by peer PE, pushes the external label if necessary, then sends the packets to the peer PE through a new intra-as MPLS tunnel. PW packets switched between the two ASBRs will not have PSN tunnel label, only PW label is switched. But the packets switched in the same AS still need two-label stack switching. The LDP Target session is still set up between the two ASBRs using the same address with BGP. The method described above can be a complement for both [I-D. draft-ietf-pwe3-segmented-pw-04] and [I-D.draft-ietf-pwe3-dynamic-ms- pw-02]. 4. MS-PW without LDP signaling between two ASBRs For the dynamic MS-PW described in [I-D.draft-ietf-pwe3-dynamic-ms- pw-02], MP-BGP is already used to exchanged the MS-PW path information. In the above scenario, LDP Target session is still needed and exists between two ASBRs. This results LDP protocol enabled between the two ASBRs. We can use MP-EBGP to signal the mapping of PW instead of LDP session between the two ASBRs. A new type of NLRI with AFI and SAFI should be assigned by IANA. MP-EBGP UPDATA packet needs to contain the PWid FEC or Generalized PWid FEC element and Generic Label TLV, see figure 2. The PWid FEC/Generalized PWid FEC and Generic Label are encoded in NLRI. The encoding method is the same with that defined in [RFC3107]. The processing of reachable NLRI is the same with that of LDP mapping message that described in [RFC 4447], while processing of unreachable NLRI is the same with that of LDP withdraw message described in [RFC 4447]. +---------------------------+ | Length (1 octet) | +---------------------------+ | Label (3 octets) | +---------------------------+ | PWid FEC (variable) | +---------------------------+ Figure 2: Encoding of NRLI for PW In this case, there is only BGP Protocol existed between the two ASBRs, LDP and other protocols are not needed. Then a very clear protocol border exists between the two ASs. In this draft, using of MP-EBGP to signal the mapping of dynamic Multi-Segment PW is suggested, since MP-BGP has now been used to exchange MS-PW path information. Jin, et al. [Page 3] Internet Draft draft-jin-pwe3-pw-inter-as-ext-00.txt March 2007 The method described above can be a complement for [I-D. draft-ietf-pwe3-dynamic-ms-pw-02]. 6. Applicability In the scenario of setting up a PW between two different ASs, and the two ASs support different kind of PSN tunnel, or Service Provider does not want to enable any PSN tunnel between two ASs or ASBRs, then a MS-PW can be set up with one PW Segment between two ASBRs that are directly connected. PSN tunnel between the two ASBRs is not needed. In the scenario that the Service Provider neither wants to distribute any loopback address to other AS, nor enable any other protocols except BGP between the two ASBRs, so as to ensure a clear border between two ASs, then MP-EBGP can be used to signal the mapping of PW and exchange MS-PW path information. 7. QoS considerations When the label is switched between the two ASBRs, the processing method of EXP is the same with before. 8. Intellectual Property Statement The IETF takes no position regarding the validity or scope of any Intellectual Property Rights or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; nor does it represent that it has made any independent effort to identify any such rights. Information on the procedures with respect to rights in RFC documents can be found in BCP 78 and BCP 79. Copies of IPR disclosures made to the IETF Secretariat and any assurances of licenses to be made available, or the result of an attempt made to obtain a general license or permission for the use of such proprietary rights by implementers or users of this specification can be obtained from the IETF on-line IPR repository at http://www.ietf.org/ipr. The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights that may cover technology that may be required to implement this standard. Please address the information to the IETF at ietf- Jin, et al. [Page 4] Internet Draft draft-jin-pwe3-pw-inter-as-ext-00.txt March 2007 ipr@ietf.org. 9. Full Copyright Statement Copyright (C) The IETF Trust (2007). This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights. This document and the information contained herein are provided on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. 10. Acknowledgments The authors wish to acknowledge the contributions of the authors [RFC 4447], [I-D.draft-ietf-pwe3-segmented-pw-04] and [I-D.draft-ietf -pwe3-dynamic-ms-pw-02]. 11. Normative References [RFC3107] "Carrying Label Information in BGP-4", Y. Rekhter., et al., rfc 3107 May 2001 [RFC4447] "Pseudowire Setup and Maintenance Using the Label Distribution Protocol (LDP)", Martini, L., et al., rfc4447 April 2006. 12. Informative References [I-D.draft-ietf-pwe3-segmented-pw-04] Martini et.al. "Segmented Pseudo Wire", draft-ietf-pwe3-segmented-pw-04.txt, IETF Work in Progress, February 2007 [I-D.draft-ietf-pwe3-dynamic-ms-pw-02] Martini et.al. "Dynamic Placement of Multi Segment Pseudo Wires", draft-ietf-pwe3- dynamic-ms-pw-02.txt, IETF Work in Progress, October 2006 13. Author Information Jin, et al. [Page 5] Internet Draft draft-jin-pwe3-pw-inter-as-ext-00.txt March 2007 Jin Lizhong ZTE Corporation No.68 Zijinghua Rd,Yuhuatai District, Nanjing. P.R.China. e-mail: jin.lizhong@zte.com.cn Feng Jun ZTE Corporation No.68 Zijinghua Rd,Yuhuatai District, Nanjing. P.R.China. e-mail: feng.jun99@zte.com.cn Liu Kebo ZTE Corporation No.68 Zijinghua Rd,Yuhuatai District, Nanjing. P.R.China. e-mail: liu.kebo@zte.com.cn Hu Kan ZTE Corporation No.68 Zijinghua Rd,Yuhuatai District, Nanjing. P.R.China. e-mail: hu.kan@zte.com.cn Wang Liangjun ZTE Corporation No.68 Zijinghua Rd,Yuhuatai District, Nanjing. P.R.China. e-mail: wang.liangjun@zte.com.cn Jin, et al. 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