CCAMP Working Group Zafar Ali Hassan Sheikh Internet Draft Cisco Systems, Inc. Tomohiro Otani KDDI R&D Laboratories, Inc. Intended status: BCP July 9, 2007 Expires: January 2008 Address Resolution for GMPLS controlled PSC Ethernet Interfaces draft-ali-arp-over-gmpls-controlled-ethernet-psc-i-04.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 This Internet-Draft will expire on August 9, 2007. Copyright Notice Copyright (C) The IETF Trust (2007). Expires January 2008 [Page 1] draft-ali-arp-over-gmpls-controlled-ethernet-psc-i-04.txt July 2007 Abstract This document outlines some interoperability issues observed with the use of ARP over GMPLS controlled Ethernet router-to-router (PSC) interfaces transiting from a non-Ethernet core, e.g., FSC or LSC GMPLS core. The document also recommends some procedures to address these issues. The aim of this document is to facilitate and ensure better interworking of GMPLS-capable Label Switching Routers (LSRs), based on experience gained in interoperability testing. Conventions used in this document In examples, "C:" and "S:" indicate lines sent by the client and server respectively. 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 RFC-2119. Table of Contents 1. Introduction...............................................2 2. Address to use for ARP Resolution..........................5 3. Security Considerations....................................5 4. IANA Considerations........................................5 5. References.................................................5 5.1. Normative References..................................5 5.2. Informative References................................5 Author's Addresses............................................6 Intellectual Property Statement...............................6 Disclaimer of Validity........................................7 1. Introduction This draft addresses the scenario where edge routers are connected via a non-Ethernet switch capable GMPLS core, e.g., FSC or LSC core [RFC3471], [RFC3473]. Furthermore, the interfaces between the router and the optical device (OXC) are Ethernet, and considered as point-to-point. Unlike POS links where a L2 adjacency resolution is not required, the Ethernet links require Expires January 2008 [Page 2] draft-ali-arp-over-gmpls-controlled-ethernet-psc-i-04.txt July 2007 that the ARP be resolved (also known as Layer 2 MAC address) before any forwarding works on this link. This draft addresses the following scenario, <---------------------- GMPLS Tunnel -----------------------> RTR1 <---- GE TE link ----> OXC <---- GE TE link ----> RTR2 segment # 1 segment # 2 Figure 1: Reference Diagram. Here TE links can be numbered or unnumbered. Similarly, tunnel interface can be numbered or unnumbered. Furthermore, segment # 1 and segment #2 may or may not be in the same subnets. When an LSP Path is established between the Ingress Router (RTR1) to Egress Router (RTR2), Ethernet interface at the two routers comes up. However, before this LSP (or interface) can forward any IP traffic, MAC address of the remote router needs to be resolved. The remote MAC address learning is the same procedure used in ARP resolution to be able to map and ip address to a MAC address on an Ethernet segment. End-point MAC address needs to be re-learned once the ARP cache entries time-out, or every time the path taken by the GMPLS LSP changes (e.g., due to re-routing or re-optimization). This introduces latency that is at least equal to the round trip delay. Such latency adds to the traffic switchover delay and consequently traffic loss for 1:1 protected LSP without extra traffic, or when LSP route changes due to re-routing (restoration) or re-optimization, etc. Interoperability issues in learning end-point MAC address using ARP are also found among vendors at various Interoperability events/ testing efforts. This is because different vendors use different IP address for ARP resolution. Some LSR vendor uses the address of the TE link at the end-point, while others adapt to use tunnel interface address for ARP resolution. When both end- point TE link address and tunnel interface addresses are unnumbered, the ARP needs to be performed using loopback addresses or unique node-ids. Some LSRs do not reply to ARP request sent to a loopback address unless proxy Arp is used or unless there is no issues with the L3 reachability of such loopback address. When tunnel interface is protected, i.e., it has working and protecting LSP-es, the ARP requested for a given tunnel IF address should resolve ARP for the physical interfaces Expires January 2008 [Page 3] draft-ali-arp-over-gmpls-controlled-ethernet-psc-i-04.txt July 2007 along the path of working and protecting LSP. Issue associated with ARP latency and traffic loss for 1:1 protected LSP without extra traffic, or when LSP route changes due to due to re-routing (restoration) or re-optimization, etc. could not be addressed. Furthermore tunnel IF address can also be unnumbered. This document provides some recommendations for the use of the MAC addresses resolution (ARP resolution) for a GMPLS LSP. In the following, we provide reason behind recommendations provided in this document. Consider following scenarios. Please refer to Figure 1. 1. When numbered TE links are used but segment # 1 and segment # 2 are in different subnets: In this case disjoint subnets are used with numbered TE links between the Ingress LSR and the Optical node, and the Egress LSR and the optical node. In this situation we really have no way of resolving ARP using the addresses of the underlying TE link Ethernet links without using static ARP entries. The issue is that the subnets are different so the ARP request received by RTR2 from RTR1 will be rejected as it is not known to RTR2, and vice versa. Instead, if the ARP request if for the GMPLS tunnel instead then there should be no problem as the GMPLS tunnel is point- to-point virtual link with IPV4 addresses in the same subnet. 2. When the GMPLS tunnel is numbered but the TE links are Unnumbered and RTR1 does not have loopback address used by RTR2 in its forwarding database, and vice versa. An example of such scenario is the case when optical and packet TE links are flooded with different IGP instances. In this case, we are again faced with the same issue of L2 ARP adjacency resolution between RTR1 and RTR2. RTR2 will reject the ARP request for RTR1 as it will not find the unnumbered address (used by RTR1) in its forwarding database. This issue would not be encountered if we were resolving the ARP on GMPLS tunnel address. 3. If the GMPLS tunnel is unnumbered then the ARP resolution needs to be done using Loopback addresses associated with the GMPLS tunnel. 4. GMPLS Protection Case: The use of the GMPLS tunnel IP address for ARP resolution can also be extended to the case where the GMPLS tunnel is providing 1:1 protection i.e. a working LSP and a protected LSP exists for the GMPLS tunnel. The protected and the working LSP of the GMPLS tunnel are typically using different physical interfaces with different MAC address and TE link addresses. In this case, using the same GMPLS tunnel IP addresses for resolving ARP for both working and the Expires January 2008 [Page 4] draft-ali-arp-over-gmpls-controlled-ethernet-psc-i-04.txt July 2007 protecting links would require the router to associate two physical interfaces with different MAC addresses with the same GMPLS tunnel IP address. The use of this implementation along with the creation of such mapping would also eliminate the problem of ARP cache timeout on the protecting link; and hence can address the above-mentioned ARP latency issue related to protection/ restoration or reoptimization case. 2. Address to use for ARP Resolution An LSR SHOULD use tunnel interface address for ARP request. An LSR, based on a local decision, can determine if the Interface is point-to-point and SHOULD resolve APR using loopback addresses. Similarly, for point-to-point interfaces, an LSR SHOULD resolve APR for two or more physical interfaces using the same IP address (this is to address ARP Latency issue mentioned-above). In the case of protected tunnels, the ARP cache SHOULD NOT timeout the ARP entry on both the working and the protecting LSPs. To meet this requirement, an LSR MAY resolve the ARP at the GMPLS tunnel setup time and MAY use an infinite ARP timeout (this is to make sure that ARP entire will not timeout as long as the GMPLS tunnel is UP). Alternatively, an LSR MAY implement a periodic ARP refresh scheme for the GMPLS tunnel to keep the ARP cache refreshed for both the working and the protected LSP. 3. Security Considerations This document does not introduce new security issues. 4. IANA Considerations This document does not require any IANA consideration. 5. References 5.1. Normative References Expires January 2008 [Page 5] draft-ali-arp-over-gmpls-controlled-ethernet-psc-i-04.txt July 2007 5.2. Informative References [RFC3471] Generalized Multi-Protocol Label Switching (GMPLS) Signaling Functional Description, RFC 3471, L. Berger, et al, January 2003. [RFC3473] "Generalized Multi-Protocol Label Switching (GMPLS) Signaling Resource ReserVation Protocol-Traffic Engineering (RSVP-TE) Extensions", RFC 3473, L. Berger, et al, January 2003. Author's Addresses Zafar Ali Cisco Systems Inc. 2000 Innovation Dr., Kanata, Ontario, K2K 3E8 Canada. Phone: (613) 889-6158 Email: zali@cisco.com Hassan Sheikh Cisco Systems Inc. 2000 Innovation Dr., Kanata, Ontario, K2K 3E8 Canada. Phone: (613) 254-3356 Email: hassans@cisco.com Tomohiro Otani KDDI R&D Laboratories, Inc. 2-1-15 Ohara Fujimino-shi Saitama, 356-8502. Japan Phone: +81-49-278-7357 Email: otani@kddilabs.jp 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. 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Disclaimer of Validity 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. 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. Expires January 2008 [Page 7]