TRILL Working Group Yizhou Li INTERNET-DRAFT Donald Eastlake Intended Status: Standard Track Linda Dunbar Huawei Technologies Radia Perlman EMC Igor Gashinsky Yahoo Expires: April 30, 2015 October 27, 2014 TRILL: ARP/ND Optimization draft-yizhou-trill-arp-optimization-00 Abstract This document describes mechanisms to optimize the ARP (Address Resolution Protocol) and ND (Neighbor Discovery) traffic in TRILL campus. Such optimization reduces the flooding over campus. 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/1id-abstracts.html The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html Copyright and License Notice Copyright (c) 2013 IETF Trust and the persons identified as the document authors. All rights reserved. Yizhou, et al [Page 1] INTERNET DRAFT Problems of Active-Active connection July 2013 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 Simplified BSD License. Table of Contents 1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.1 Terminology . . . . . . . . . . . . . . . . . . . . . . . . 3 2 IP/MAC address mappings . . . . . . . . . . . . . . . . . . . . 3 3. Handling ARP/ND messages . . . . . . . . . . . . . . . . . . . 4 3.1 Get the mapping information of the sender's IP and MAC for non-zero IP. . . . . . . . . . . . . . . . . . . . . . . . . 4 3.2 Determine how to reply the ARP/ND request. . . . . . . . . . 5 3.3 Determine how to handle the ARP/ND response. . . . . . . . . 6 4. Handling RARP (Reverse Address Resolution Protocol) messages . 6 5 Security Considerations . . . . . . . . . . . . . . . . . . . . 6 6 IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 7 6 References . . . . . . . . . . . . . . . . . . . . . . . . . . 7 5.1 Normative References . . . . . . . . . . . . . . . . . . . 7 5.2 Informative References . . . . . . . . . . . . . . . . . . 8 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 8 Yizhou, et al [Page 2] INTERNET DRAFT Problems of Active-Active connection July 2013 1 Introduction IEEE 802.1 bridges forward an ARP/ND query as an ordinary broadcast/multicast frame to all links belonging to the same VLAN. RBridges May implement an "optimized ARP/ND response" when the target's location is assumed to be known by the ingress RBridge. ARP/ND query flooding can be avoided. 1.1 Terminology 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 [RFC2119]. The acronyms and terminology in [RFC6325] is used herein with the following additions: TRILL switch - an alternative term for an RBridge. 2 IP/MAC address mappings Traditionally an RBridge learns the MAC and nickname correspondence of a remote host as per [RFC6325] from TRILL data frame received. No IP address information is learned directly from the TRILL data frame. Interface Addresses (IA) APPsub-TLV [IA] enhanced TRILL base protocol by allowing IP and MAC address mappings to be distributed at the control plane by any RBridge. This APPsub-TLV appears inside the TRILL GENINFO TLV specified in ESADI [RFC7357] but may also occur in other application contexts. Edge Directory Assist Mechanisms [DirMech] makes use of this APPsub-TLV too for its push model. An RBridge can easily know the IP/MAC address mappings of the hosts in the local network that is attached to it via the access ports by receiving the ARP [RFC826] or ND [RFC4861] messages. If the RBridge has not saved sender's IP/MAC address pair in the received data packet, it may save the information and use Interface Addresses APPsub-TLV distribute them to other RBridges. Then the relevant remote RBridges (normally those attached by hosts from the same Data Label as the original ARP/ND messages) receives and saves such mapping information too. There are others ways that RBridges saves IP/MAC address mappings in advance, e.g. import from management system and distribution by directory servers [DirMech]. The examples given above show that RBridges may have saved a host's triplet of {IP address, MAC address, ingress nickname} for a given Yizhou, et al [Page 3] INTERNET DRAFT Problems of Active-Active connection July 2013 Data Label (VLAN or FGL) before that host sends or receives any real data packet. Note such information may or may not be a complete list and may or may not exist on all RBridges. Information are possibly from different sources. RBridges can use Flags Field in APPsub-TLV to identify if the source is directory server or local observation by the sender. Different confidence level may also be used to indicate the reliability of the mapping information. 3. Handling ARP/ND messages ARP [RFC826] message is detected by its Ethertype of 0x0806. ND [RFC4861] defines five different ICMPv6 packet types. ARP/ND is commonly used on a link to (1) query for the MAC address corresponding to an IPv4 address, (2) test if an IPv4/IPv6 address is already in use, or (3) to announce the new or updated info on any of IPv4/IPv6 address, MAC address, and/or point of attachment. To simplify the text, we use the following terms in this section. IP address - indicated protocol address which is normally IPv4 address in ARP, IPv6 address in ND sender's IP/MAC address - sender protocol/hardware address in ARP, source IP address and source link- layer address in ND target's IP/MAC address - target protocol/hardware address in ARP, target address and target link- layer address in ND When an ingress RBridge receives an ARP/ND message, it can perform the following steps described in sub-sections. 3.1 Get the mapping information of the sender's IP and MAC for non-zero IP. If the information of the sender's MAC has not been saved by the ingress RBridge before, populate the information of sender's IP/MAC to its ARP table; else if the sender's MAC has been saved before however with a different IP address mapped, the RBridge should verify if a duplicate IP address has already been in use. The RBridge may take different strategies to do so, for example, ask the authoritative entity like directory servers or encapsulate and unicast the ARP/ND message to the location where it believes a duplicate address is in use. The ingress RBridge may use IA APPsub-TLV [IA] with the Local flag set in ESADI [RFC7357] to distribute any new or updated IP/MAC information obtained in this step. If push directory server is used, such information can be distributed as per [DirMech]. Yizhou, et al [Page 4] INTERNET DRAFT Problems of Active-Active connection July 2013 3.2 Determine how to reply the ARP/ND request. a) If the message is a generic ARP/ND request and the ingress RBridge knows target's IP address, the ingress RBridge may decide to take one or combination of the following actions: 1. send an ARP/ND response directly to the querier, with the target's MAC address, as believed by the ingress RBridge 2. encapsulate the ARP/ND request to the target's Designated RBridge, and have the Designated RBridge at the target forward the query to the target. This behavior has the advantage that a response to the request is authoritative. If the request does not reach the target, then the querier does not get a response 3. block ARP/ND requests that occur for some time after a request to the same target has been launched, and then respond to the querier when the response to the recently-launched query to that target is received 4. pull the most up-to-date records if pull directory server is in use [DirMech] and reply to the querier 5. flood the request as per RFC6325 b) If the message is a generic ARP request and the ingress RBridge does not know target's IP address, the ingress RBridge may take one of the following actions. 1. flood the message as per RFC6325 2. use directory server to pull the information [DirMech] and reply to the querier 3. drop the message c) If the message is a gratuitous ARP which can be identified by the same sender's and target's "protocol" address fields or an Unsolicited Neighbor Advertisements [RFC4861] in ND: The RBridge may use IA APPsub-TLV [IA] with the Local flag set to distribute the sender's MAC and IP mapping information. When directory server is deployed and complete Push Directory information is used by all the TRILL switches in the Data Label, gratuitous ARP or unsolicited NA SHOULD be discarded rather than ingressed. Otherwise, they are either ingressed and flooded as per RFC6325 or discarded depending on local policy. Yizhou, et al [Page 5] INTERNET DRAFT Problems of Active-Active connection July 2013 d) If the message is a Address Probe ARP Query [RFC5227] which can be identified by the sender's protocol (IPv4) address field being zero and the target's protocol address field being the IPv4 address to be tested or a Neighbor Solicitation for DAD (Duplicate Address Detection) which has unspecified source address [RFC4862]: it should be handled as the generic ARP message as in a) and b). It should be noted in the case of secure neighbor discovery (SEND) [RFC3971], cryptography might prevent local reply by the ingress RBridge, since the RBridge would not be able to sign the response with the target's private key. It is not essential that all RBridges use the same strategy for which option to select for a particular ARP/ND query. It is up to the implementation. 3.3 Determine how to handle the ARP/ND response. If the ingress RBridge R1 decides to unicast the ARP/ND request to the target's Designated RBridge R2 as shown in subsection 3.2 item a or to flood the request as per RFC6325, then R2 decapsulates the query, and initiate an ARP/ND query on the target's link. When/if the target responds, R2 encapsulates and unicast the response to R1, which decapsulates the response and send it to the querier. R2 should initiates a link state update to inform all the other RBridges of the target's location, layer 3 address, and layer 2 address, in addition to forwarding the reply to the querier. The update message can be carried by IA APPsub-TLV [IA] with the Local flag set in ESADI [RFC7357] or as per [DirMech] if push directory server is in use. 4. Handling RARP (Reverse Address Resolution Protocol) messages RARP [RFC903] uses the same packet format as ARP but a different Ethertype (0x8035) and opcode values. Its use is similar to the generic ARP Request/Response as described in 3.2 a) and b). The difference is that it is intended to query for the target "protocol" address corresponding to the target "hardware" address provided. It should be handled by doing a local cache or directory server lookup on the target "hardware" address provided to find a mapping to the desired "protocol" address. Normally, look up a MAC address to find the corresponding IP address. 5 Security Considerations ARP and ND messages can be easily forged. Therefore the learning of MAC/IP addresses from them should not be considered as reliable. RBridge can use the confidence level in received IA APPsub-TLV to determine the reliability of MAC/IP address mapping. It is up to the Yizhou, et al [Page 6] INTERNET DRAFT Problems of Active-Active connection July 2013 implementation to decide if an RBridge should distribute the IP and MAC address mappings received from ARP/ND to other RBridges in the same VLAN/FGL. The ingress RBridge should also rate limit the ARP/ND queries for the same target to be injected to the TRILL campus prevent the possible attack. 6 IANA Considerations No IANA action is required. RFC Editor: please delete this section before publication. 6 References 5.1 Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman, "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861, September 2007. [RFC4862] Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless Address Autoconfiguration", RFC 4862, September 2007. [RFC826] Plummer, D., "An Ethernet Address Resolution Protocol", RFC 826, November 1982. [RFC903] Finlayson, R., Mann, T., Mogul, J., and M. Theimer, "A Reverse Address Resolution Protocol", STD 38, RFC 903, June 1984 [RFC6165] Banerjee, A. and D. Ward, "Extensions to IS-IS for Layer-2 Systems", RFC 6165, April 2011. [RFC6325] Perlman, R., et.al. "RBridge: Base Protocol Specification", RFC 6325, July 2011. [RFC6326bis] Eastlake, D., Banerjee, A., Dutt, D., Perlman, R., and A. Ghanwani, "TRILL Use of IS-IS", draft-eastlake-isis- rfc6326bis, work in progress. [RFC6327bis] Eastlake 3rd, D., R. Perlman, A. Ghanwani, H. Yang, and Yizhou, et al [Page 7] INTERNET DRAFT Problems of Active-Active connection July 2013 V. Manral, "TRILL: Adjacency", draft-ietf-trill- rfc6327bis, work in progress. [RFC6439] Eastlake, D. et.al., "RBridge: Appointed Forwarder", RFC 6439, November 2011. 5.2 Informative References [RFC3971] Arkko, J., Ed., Kempf, J., Zill, B., and P. Nikander, "SEcure Neighbor Discovery (SEND)", RFC 3971, March 2005. [RFC5227] Cheshire, S., "IPv4 Address Conflict Detection", RFC 5227, July 2008. [RFC7067] Dunbar, L., Eastlake 3rd, D., Perlman, R., and I. Gashinsky, "Directory Assistance Problem and High-Level Design Proposal", RFC 7067, November 2013. [IA] Eastlake, D., Li Y., R. Perlman, "TRILL: Interface Addresses APPsub-TLV", draft-eastlake-trill-ia-appsubtlv, work in progress. [DirMech] Dunbar, L., Eastlake 3rd, D., Perlman, R., I. Gashinsky. and Li Y., TRILL: Edge Directory Assist Mechanisms", draft-ietf-trill-directory-assist-mechanisms, work in progress. Authors' Addresses Yizhou Li Huawei Technologies 101 Software Avenue, Nanjing 210012 China Phone: +86-25-56625375 EMail: liyizhou@huawei.com Donald Eastlake Huawei R&D USA 155 Beaver Street Milford, MA 01757 USA Phone: +1-508-333-2270 Email: d3e3e3@gmail.com Yizhou, et al [Page 8] INTERNET DRAFT Problems of Active-Active connection July 2013 Linda Dunbar Huawei Technologies 5430 Legacy Drive, Suite #175 Plano, TX 75024, USA Phone: +1-469-277-5840 EMail: ldunbar@huawei.com Radia Perlman EMC 2010 256th Avenue NE, #200 Bellevue, WA 98007 USA Email: Radia@alum.mit.edu Igor Gashinsky Yahoo 45 West 18th Street 6th floor New York, NY 10011 USA EMail: igor@yahoo-inc.com Yizhou, et al [Page 9]