Network Working Group V. Manral, Ed. Internet-Draft IPInfusion Inc. Intended status: Informational October 02, 2010 Expires: April 5, 2011 Bidirectional Forwarding Detection (BFD) Encapsulation over TRILL draft-manral-trill-bfd-encaps-00 Abstract BFD is a widely deployed Operation, Administration, and Maintenance (OAM) mechanism in IP and MPLS networks. However, in the present form a BFD packet cannot be sent over a TRILL network as it is either IP/ UDP encapsulated or encapsulated directly over MPLS or using ACH encapsulation. This document defines BFD encapsulation over TRILL to address this shortcoming. Requirements Language 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]. 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 5, 2011. Copyright Notice Copyright (c) 2010 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 Manral Expires April 5, 2011 [Page 1]
Internet-Draft BFD TRILL Encapsulation October 2010 (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 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. BFD over TRILL . . . . . . . . . . . . . . . . . . . . . . . . 3 4. BFD TRILL Header . . . . . . . . . . . . . . . . . . . . . . . 4 5. BFD Control Packet Encapsulation . . . . . . . . . . . . . . . 5 6. Security Considerations . . . . . . . . . . . . . . . . . . . . 5 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 6 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 6 9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 6 9.1. Normative References . . . . . . . . . . . . . . . . . . . 6 9.2. Informative References . . . . . . . . . . . . . . . . . . 6 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 6 Manral Expires April 5, 2011 [Page 2]
Internet-Draft BFD TRILL Encapsulation October 2010 1. Introduction Faster convergence is a very critical feature of TRILL networks. Networks use relatively slow "TRILL Hello" mechanisms in the IS-IS protocol, to detect failures. BFD protocol provides a low-overhead, short-duration detection of failures in the path between forwarding engines. This document describes a TRILL encapsulation for BFD packets for networks that do not use IP addressing or for ones where it is not desireable. 2. Terminology MPLS: Multi Protocol Label Switching IS-IS: Intermediate-System to Intermediate-System TTL: Time To Live 3. BFD over TRILL BFD over TRILL support is similar to BFD over IP support except where it is explicitly so mentioned. When running BFD over TRILL both Single Hop as well as in Multi Hop sessions are supported. Asynchronous mode is supported, however the demand mode is not supported for TRILL. BFD over TRILL supports the Echo function, however this can be used for only Single hop sessions. The TRILL Header Hop count in the BFD packets sent out with a value of 63. To prevent spoofing attacks, the TRILL Hop count of a received session is checked. For a single Hop session if the Hop count is less than 63 the packet is discarded if the GTSM mode [RFC5082] is set. For Multi Hop sessions the Hop count check can be disabled or the bfdTrillAcceptedHopCount value can be configured. If a packet is received with a hop count of less than bfdTrillAcceptedHopCount, the packet is discarded. The format of the echo packet is not defined. A new BFD TRILL header is defined. Authentication mechanisms as supported in BFD are also supported for BFD running over TRILL. Manral Expires April 5, 2011 [Page 3]
Internet-Draft BFD TRILL Encapsulation October 2010 4. BFD TRILL Header 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 2 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Reserved |E|M| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 1: BFD TRILL Header When BFD TRILL Header is a 32 bit field which is followed by the BFD packet. 2 bits in the header are defined. M - Multihop session E - BFD Echo packet M bit MUST be set for a BFD Multi Hop session. E bit MUST be set for Echo packets. Other flags are sent with a value of 0 and ignored on receipt Manral Expires April 5, 2011 [Page 4]
Internet-Draft BFD TRILL Encapsulation October 2010 5. BFD Control Packet Encapsulation Outer Ethernet Header: +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Next Hop Destination Address | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Next Hop Destination Address | Sending RBridge MAC Address | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Sending RBridge Port MAC Address | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Ethertype = C-Tag [802.1Q] | Outer.VLAN Tag Information | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ TRILL Header: +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Ethertype = TRILL | V | R |M|Op-Length| Hop Count | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Egress (Dist. Tree) Nickname | Ingress (Origin) Nickname | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Inner Ethernet Header: +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Dest-RBridge MAC Address | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Dest-RBridge MAC continued | Origin RBridge MAC Address | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Origin RBridge MAC Address continued | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Ethertype = C-Tag [802.1Q] | Inner.VLAN Tag Information | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Ethertype = TRILL-BFD | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ BFD Payload prefixed by BFD TRILL HEADER (formatted as BFD): +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | BFD TRILL HEADER + BFD PACKET DATA PAYLOAD | Frame Check Sequence: +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | FCS (Frame Check Sequence) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 2: BFD encapsulation 6. Security Considerations This draft raises no new security considerations than those already mentioned in the BFD [RFC5880]. By keeping a seperate flag for Single Hop and Multihop sessions it allows the TTL check to be performed thus preventing spoofing of packets. Manral Expires April 5, 2011 [Page 5]
Internet-Draft BFD TRILL Encapsulation October 2010 However the same is possible even without the changes mentioned in this document. A device should rate limit the LSP ping packets redirected to the CPU so that the CPU is not overwhelmed. 7. IANA Considerations IANA maintains the registry for the Ether Type and a new Ether type for TRILL-BFD is requested to for the packet procedures defined in the draft. The suggested value is XX. 8. Acknowledgements The authors would like to thank a lot of folks. Names will be disclosed soon. 9. References 9.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC5082] Gill, V., Heasley, J., Meyer, D., Savola, P., and C. Pignataro, "The Generalized TTL Security Mechanism (GTSM)", RFC 5082, October 2007. [RFC5880] Katz, D. and D. Ward, "Bidirectional Forwarding Detection (BFD)", RFC 5880, June 2010. 9.2. Informative References Author's Address Vishwas Manral (editor) IPInfusion Inc. 1188 E. Arques Ave. Sunnyvale, CA 94085 USA Phone: 408-400-1900 Fax: Email: vishwas@ipinfusion.com URI: Manral Expires April 5, 2011 [Page 6]