IDR G. Van de Velde Internet-Draft K. Patel Intended status: Standards Track Cisco Systems Expires: April 02, 2013 R. Raszuk NTT MCL Inc. R. Bush Internet Initiative Japan October 2012 BGP Remote-Next-Hop draft-vandevelde-idr-remote-next-hop-02 Abstract The BGP Remote-Next-Hop is a new optional transitive attribute intended to facilitate automatic tunneling across an AS on a per address family basis. The attribute carries one or more tunnel end- points for a NLRI. Additionally, tunnel encapsulation information is communicated to successfully setup these tunnels. Status of This Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. 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." This Internet-Draft will expire on April 02, 2013. Van de Velde, et al. Expires April 02, 2013 [Page 1] Internet-Draft October 2012 Copyright Notice Copyright (c) 2012 IETF Trust and the persons identified as the 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 Simplified BSD License. This document may not be modified, and derivative works of it may not be created, and it may not be published except as an Internet-Draft. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Requirements Language . . . . . . . . . . . . . . . . . . . . 2 3. Tunnel Encapsulation attribute versus BGP Remote-Next-Hop attribute . . . . . . . . . . . . . . . . . . . . . . . . . . 3 4. BGP Remote-Next-Hop attribute TLV Format . . . . . . . . . . 3 5. Use Case scenarios . . . . . . . . . . . . . . . . . . . . . . 4 5.1. Multi-homing for IPv6 . . . . . . . . . . . . . . . . . . 4 5.2. Dynamic Network Overlay Infrastructure . . . . . . . . . . 5 5.3. The Tunnel end-point is NOT the originating BGP speaker . 5 5.4. Networks that do not support BGP Remote-Next-Hop attribute 5 5.5. Networks that do NOT support BGP Remote-Next-Hop attribute 5 6. BGP Remote-Next-Hop Community . . . . . . . . . . . . . . . . 5 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5 8. Security Considerations . . . . . . . . . . . . . . . . . . . 6 8.1. Protecting the validity of the BGP Remote-Next-Hop attribut 6 9. Privacy Considerations . . . . . . . . . . . . . . . . . . . . 6 10. Change Log . . . . . . . . . . . . . . . . . . . . . . . . . . 6 11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 6 11.1. Normative References . . . . . . . . . . . . . . . . . . 6 11.2. Informative References . . . . . . . . . . . . . . . . . 7 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 7 1. Introduction [RFC5512] defines an attribute attached to an NLRI to signal tunnel end-point encapsulation information between two BGP speakers. It assumes that the exchanged tunnel endpoint is the NLRI. This document defines a new BGP transitive attribute known as a Remote-Next-Hop BGP attribute for Intra-AS and Inter-AS usage which removes that assumption. The tunnel endpoint information and the tunnel encapsulation information is carried within a Remote-Next-Hop BGP attribute. This attribute is tagged on an any BGP NLRI. This way the Address Family (AF) of the NLRI exchanged is decoupled from the tunnel SAFI address- family defined in [RFC5512]. 2. Requirements Language Van de Velde, et al. Expires April 02, 2013 [Page 2] Internet-Draft October 2012 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" are to be interpreted as described in [RFC2119] only when they appear in all upper case. They may also appear in lower or mixed case as English words, without any normative meaning. 3. Tunnel Encapsulation attribute versus BGP Remote-Next-Hop attribute The Tunnel Encapsulation attribute [RFC5512] is based on the principle that the tunnel end-point is the BGP speaker originating the update and is inserted as the NLRI in the exchange, with the consequence that it is impossible to set the endpoint it to an arbitrary IP address. There are use cases where it is desired that the tunnel end-point address should be a different address, or set of addresses, than the originating BGP speaker. The BGP Remote-Next-Hop attribute provides the ability to have one or more different tunnel end-point addresses from either the IPv4 and/or the IPv6 address-families. The sub-TLVs from the Tunnel Encapsulation Attribute [RFC5512] are reused for the BGP Next-Hop-Attribute. Due to the intrinsic nature of both attributes, the tunnel encapsulation end-point assumes that the tunnel end-point is both the NLRI exchanged and the originating router, while the BGP Remote-Next- Hop attribute is inserted for an exchanged NLRI by adding a set of tunnel end-points, these two attributes are mutually exclusive. 4. BGP Remote-Next-Hop attribute TLV Format This attribute is an optional transitive attribute [RFC1771]. The BGP Remote-Next-Hop attribute is is composed of a set of Type- Length-Value (TLV) encodings. The type code of the attribute is (IANA to assign). Each TLV contains information corresponding to a particular tunnel technology and tunnel end-point Address. The TLV is structured as follows: Van de Velde, et al. Expires April 02, 2013 [Page 3] Internet-Draft October 2012 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tunnel Type (2 Octets) | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Addr len | Tunnel Address (IPv4 or IPv6) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | AS Number | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tunnel Parameters | ~ ~ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Tunnel Type (2 octets): identifies the type of tunneling technology being signaled. This document defines the following types: - L2TPv3 over IP [RFC3931]: Tunnel Type = 1 - GRE [RFC2784]: Tunnel Type = 2 - IP in IP [RFC2003] [RFC4213]: Tunnel Type = 7 Unknown types MUST be ignored and skipped upon receipt. Length (2 octets): the total number of octets of the value field. Tunnel Address Length - Addr len (1 octet): Length of Tunnel Address. Set to 4 bytes for an IPv4 address and 16 bytes for an IPv6 address. AS Number - The AS number originating the BGP Remote-Next-Hop attribute and is either a 2-byte AS or 4-Byte AS number Value (variable): comprised of multiple sub-TLVs. Each sub-TLV consists of three fields: a 1-octet type, 1-octet length, and zero or more octets of value. The sub-TLV definitions and the sub-TLV data are described in depth in [RFC5512]. 5. Use Case scenarios This section provides a short overview of some use-cases for the BGP Remote-Next-Hop attribute. Use of the BGP Remote-Next-Hop is not limited to the examples in this section. 5.1. Multi-homing for IPv6 When an end-user IPv6 network is multi-homed to the Internet, it may be assigned more than a single prefix originated by various upstream ASs. Each AS prefers to only announce a supernet of all its assigned IPv6 prefixes, unlike IPv4 where the AS announced the end-users assigned prefix. The goal of this BGP policy behaviour is to keep the number of entries in the IPv6 global BGP table to a minimum, it also it also results in well known resiliency improvements. Van de Velde, et al. Expires April 02, 2013 [Page 4] Internet-Draft October 2012 For example, if an end-user IPv6 is peering with 2 different Service providers AS1 and AS2. In this case the IPv6 end-user will have at least one prefix assigned from each of these service providers. The devices at the IPv6 end-user will each receive an address from these prefixes. The devices will in most cases, when building IPv6 sessions (TCP, etc...), do so with only a single IPv6 address. The decision which IPv6 address the device will use is documented in [RFC3484]. If one if the links between the end-user and one of the neighboring AS's breaks, a consequence will be that a set of sessions need to be reset, or that a section of the end-user network becomes unreachable. With usage of the BGP-remote-Next-Hop attribute the service provider can tunnel that packet towards an alternate BGP Remote-Next-Hop at the end-users alternate provider and restore the network connectivity even though the local link towards the end-user is broken. 5.2. Dynamic Network Overlay Infrastructure With the BGP Remote-Next-Hop feature it is possible to build and dynamically create an overlay tunneled network with privacy, traffic isolation, and virtual private networks. 5.3. The Tunnel end-point is NOT the originating BGP speaker Note that, in each network environment, the originating router is the preferred tunnel end-point server. It may be that the network administrator has deployed an independent set of tunnel end-point servers across their network, which may or may not speak BGP. The BGP Remote-Next-Hop attribute provides the ability to signal this via BGP. 5.4. Networks that do not support BGP Remote-Next-Hop attribute If a device does not support this attribute, and receives this attribute, then normal NLRI BGP forwarding is used as the attribute is optional and transitive. 5.5. Networks that do NOT support BGP Remote-Next-Hop attribute If a BGP speaker does understand this attribute, and receives this attribute, then the BGP speaker MAY, by configuration, skip use or not use the information within this attribute. 6. BGP Remote-Next-Hop Community place-holder for an BGP extension to signal valid prefixes allowed to be considered as tunnel end-points. To be completed. 7. IANA Considerations This memo asks the IANA for a new BGP attribute assignment. Van de Velde, et al. Expires April 02, 2013 [Page 5] Internet-Draft October 2012 8. Security Considerations This technology could be used as technology as man in the middle attack, however with existing RPKI validation for BGP that risk is reduced. The distribution of Tunnel end-point address information can result in potential DoS attacks if the information is sent by malicious organisations. Therefore is it strongly recommended to install traffic filters, IDSs and IPSs at the perimeter of the tunneled network infrastructure. 8.1. Protecting the validity of the BGP Remote-Next-Hop attribute It is possible to inject a rogue BGP Remote-Next-Hop attribute to an NLRI resulting in Monkey-In-The-Middle attack (MITM). To avoid this type of MITM attack, it is strongly recommended to use a technology a mechanism to verify that for NLRI it is the expected BGP Remote-Next- Hop. We anticipate that this can be done with an expansion of RPKI- Based origin validation, see [I-D.ietf-sidr-pfx-validate]. This does not avoid the fact that rogue AS numbers may be inserted or injected into the AS-Path. To achieve protection against that threat BGP Path Validation should be used, see [I-D.ietf-sidr-bgpsec- overview]. 9. Privacy Considerations This proposal may introduce privacy issues, however with BGP security mechanisms in place they should be prevented. 10. Change Log Initial Version: 16 May 2012 Hacked for -01: 17 July 2012 11. References 11.1. Normative References [RFC1771] Rekhter, Y. and T. Li, "A Border Gateway Protocol 4 (BGP-4)", RFC 1771, March 1995. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC2784] Farinacci, D., Li, T., Hanks, S., Meyer, D. and P. Traina, "Generic Routing Encapsulation (GRE)", RFC 2784, March 2000. [RFC3484] Draves, R., "Default Address Selection for Internet Protocol version 6 (IPv6)", RFC 3484, February 2003. Van de Velde, et al. Expires April 02, 2013 [Page 6] Internet-Draft October 2012 [RFC3931] Lau, J., Townsley, M. and I. Goyret, "Layer Two Tunneling Protocol - Version 3 (L2TPv3)", RFC 3931, March 2005. [RFC4213] Nordmark, E. and R. Gilligan, "Basic Transition Mechanisms for IPv6 Hosts and Routers", RFC 4213, October 2005. [RFC5512] Mohapatra, P. and E. Rosen, "The BGP Encapsulation Subsequent Address Family Identifier (SAFI) and the BGP Tunnel Encapsulation Attribute", RFC 5512, April 2009. 11.2. Informative References [I-D.ietf-sidr-bgpsec-overview] Lepinski, M. and S. Turner, "An Overview of BGPSEC", Internet-Draft draft-ietf-sidr-bgpsec-overview-02, May 2012. [I-D.ietf-sidr-pfx-validate] Mohapatra, P., Scudder, J., Ward, D., Bush, R. and R. Austein, "BGP Prefix Origin Validation", Internet-Draft draft-ietf-sidr-pfx-validate-10, October 2012. Authors' Addresses Gunter Van de Velde Cisco Systems De Kleetlaan 6a Diegem 1831 Belgium Phone: +32 2704 5473 Email: gvandeve@cisco.com Keyur Patel Cisco Systems 170 W. Tasman Drive San Jose, CA 95124 95134 USA Email: keyupate@cisco.com Robert Raszuk NTT MCL Inc. 101 S Ellsworth Avenue Suite 350 San Mateo, CA 94401 US Email: robert@raszuk.net Van de Velde, et al. Expires April 02, 2013 [Page 7] Internet-Draft October 2012 Randy Bush Internet Initiative Japan 5147 Crystal Springs Bainbridge Island, Washington 98110 US Email: randy@psg.com Van de Velde, et al. Expires April 02, 2013 [Page 8]