Internet Engineering Task Force N. Akiya Internet-Draft C. Pignataro Intended status: Standards Track D. Ward Expires: February 2, 2015 Cisco Systems August 1, 2014 Seamless Bidirectional Forwarding Detection (S-BFD) for IPv4, IPv6 and MPLS draft-akiya-bfd-seamless-ip-04 Abstract This document defines procedures to use Seamless Bidirectional Forwarding Detection (S-BFD) for IPv4, IPv6 and MPLS environments. 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 February 2, 2015. Copyright Notice Copyright (c) 2014 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 Akiya, et al. Expires February 2, 2015 [Page 1] Internet-Draft Seamless BFD for IP August 2014 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 . . . . . . . . . . . . . . . . . . . . . . . . 2 2. S-BFD UDP Port . . . . . . . . . . . . . . . . . . . . . . . 2 3. S-BFD Echo UDP Port . . . . . . . . . . . . . . . . . . . . . 3 4. S-BFD Packet Demultiplexing . . . . . . . . . . . . . . . . . 3 5. Initiator Procedures . . . . . . . . . . . . . . . . . . . . 3 5.1. Details of S-BFD Packet Sent by SBFDInitiator . . . . . . 3 5.2. Target vs. Remote Entity (S-BFD Discriminator) . . . . . 4 6. Responder Procedures . . . . . . . . . . . . . . . . . . . . 4 6.1. Details of S-BFD Packet Sent by SBFDReflector . . . . . . 5 7. Security Considerations . . . . . . . . . . . . . . . . . . . 5 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6 10. Contributing Authors . . . . . . . . . . . . . . . . . . . . 6 11. References . . . . . . . . . . . . . . . . . . . . . . . . . 7 11.1. Normative References . . . . . . . . . . . . . . . . . . 7 11.2. Informative References . . . . . . . . . . . . . . . . . 7 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7 1. Introduction Seamless Bidirectional Forwarding Detection (S-BFD), [I-D.ietf-bfd-seamless-base], defines a generalized mechanism to allow network nodes to seamlessly perform continuity checks to remote entities. This document defines necessary procedures to use S-BFD on IPv4, IPv6 and MPLS environments. The reader is expected to be familiar with the IP, MPLS BFD and S-BFD terminologies and protocol constructs. 2. S-BFD UDP Port A new UDP port is defined for the use of the S-BFD on IPv4, IPv6 and MPLS environments: TBD1. SBFDReflector session MUST listen for incoming S-BFD packets on the port TBD1. SBFDInitiator sessions MUST transmit S-BFD packets with destination port TBD1. The source port of the S-BFD packets transmitted by SBFDInitiator sessions MUST be in the range 49152 through 65535. The same UDP source port number MUST be used for all S-BFD packets associated with a particular SBFDInitiator session. The source port number MAY be unique among all SBFDInitiator sessions on the system. Akiya, et al. Expires February 2, 2015 [Page 2] Internet-Draft Seamless BFD for IP August 2014 3. S-BFD Echo UDP Port A new UDP port is defined for the use of the S-BFD Echo function on IPv4, IPv6 and MPLS environments: TBD2. This document defines only the UDP port value for the S-BFD Echo function. 4. S-BFD Packet Demultiplexing Received BFD control packet MUST be demultiplexed with the destination UDP port field. If the port is TBD1, then the packet MUST be looked up to locate a corresponding SBFDReflector session based on the value from the "your discriminator" field in the table describing S-BFD discriminators. If the port is not TBD1, then the packet MUST be looked up to locate a corresponding SBFDInitiator session or classical BFD session based on the value from the "your discriminator" field in the table describing BFD discriminators. If the located session is an SBFDInitiator, then the destination IP address of the packet SHOULD be validated to be for self. 5. Initiator Procedures S-BFD packets are transmitted with IP header, UDP header and BFD control header ([RFC5880]). When S-BFD packets are explicitly label switched (i.e. not IP routed which happen to go over an LSP, but explicitly sent on a specific LSP), the former is prepended with a label stack. Note that this document does not make a distinction between a single-hop S-BFD scenario and a multi-hop S-BFD scenario, both scenarios are supported. Necessary values in the BFD control headers are described in [I-D.ietf-bfd-seamless-base]. Section 5.1 describes necessary values in the MPLS header, IP header and UDP header when an SBFDInitiator on the initiator is sending S-BFD packets. 5.1. Details of S-BFD Packet Sent by SBFDInitiator o Specifications common to both IP routed S-BFD packets and explicitly label switched S-BFD packets: * Source IP address field of the IP header MUST be set to a local IP address. * UDP destination port MUST be set to a well-known UDP destination port assigned for S-BFD: TBD1. * UDP source port MUST be set to a value in the range 49152 through 65535. Akiya, et al. Expires February 2, 2015 [Page 3] Internet-Draft Seamless BFD for IP August 2014 o Specifications for IP routed S-BFD packets: * Destination IP address field of the IP header MUST set to an IP address of the target. * TTL field of the IP header SHOULD be set to 255. o Specifications for explicitly label switched S-BFD packets: * S-BFD packets MUST have the label stack that is expected to reach the target. * TTL field of the top most label SHOULD be 255. * The destination IP address MUST be chosen from the 127/8 range for IPv4 and from the 0:0:0:0:0:FFFF:7F00/104 range for IPv6. * TTL field of the IP header MUST be set to 1. 5.2. Target vs. Remote Entity (S-BFD Discriminator) Typically, an S-BFD packet will have "your discriminator" field corresponding to an S-BFD discriminator of the remote entity located on the target network node defined by the destination IP address or the label stack. It is, however, possible for an SBFDInitiator to carefully set "your discriminator" and TTL fields to perform a continuity test towards a target but to a transit network node. Section 5.1 intentionally uses the word "target", instead of "remote entity", to accommodate this possible S-BFD usage through TTL expiry. This also requires S-BFD packets not be dropped by the responder node due to TTL expiry. Thus implementations on the responder MUST allow received S-BFD packets taking TTL expiry exception path to reach corresponding reflector BFD session. 6. Responder Procedures S-BFD packets are IP routed back to the initiator, and will have IP header, UDP header and BFD control header. Necessary values in the BFD control header are described in [I-D.ietf-bfd-seamless-base]. Section 6.1 describes necessary values in the IP header and UDP header when an SBFDReflector on the responder is sending S-BFD packets. Akiya, et al. Expires February 2, 2015 [Page 4] Internet-Draft Seamless BFD for IP August 2014 6.1. Details of S-BFD Packet Sent by SBFDReflector o Destination IP address field of the IP header MUST be copied from source IP address field of received S-BFD packet. o Source IP address field of the IP header MUST be set to a local IP address. o TTL field of the IP header SHOULD be set to 255. o UDP destination port MUST be copied from received UDP source port. o UDP source port MUST be copied from received UDP destination port. 7. Security Considerations Security considerations for S-BFD are discussed in [I-D.ietf-bfd-seamless-base]. Additionally, implementing the following measures will strengthen security aspects of the mechanism described by this document: o Implementations MUST provide filtering capability based on source IP addresses of received S-BFD packets: [RFC2827]. o Implementations MUST NOT act on received S-BFD packets containing Martian addresses as source IP addresses. o Implementations MUST ensure that response S-BFD packets generated to the initiator by the SBFDReflector have a reachable target (ex: destination IP address). 8. IANA Considerations A new value TBD1 is requested from the "Service Name and Transport Protocol Port Number Registry". The requested registry entry is: Akiya, et al. Expires February 2, 2015 [Page 5] Internet-Draft Seamless BFD for IP August 2014 Service Name (REQUIRED) s-bfd Transport Protocol(s) (REQUIRED) udp Assignee (REQUIRED) IESG Contact (REQUIRED) BFD Chairs Description (REQUIRED) Seamless Bidirectional Forwarding Detection (S-BFD) Reference (REQUIRED) draft-akiya-bfd-seamless-ip Port Number (OPTIONAL) TBD1 (Requesting 7784) A new value TBD2 is requested from the "Service Name and Transport Protocol Port Number Registry". The requested registry entry is: Service Name (REQUIRED) s-bfd-echo Transport Protocol(s) (REQUIRED) udp Assignee (REQUIRED) IESG Contact (REQUIRED) BFD Chairs Description (REQUIRED) Seamless Bidirectional Forwarding Detection (S-BFD) Echo Function Reference (REQUIRED) draft-akiya-bfd-seamless-ip Port Number (OPTIONAL) TBD2 (Requesting 7785) 9. Acknowledgements Authors would like to thank Marc Binderberger from Cisco Systems for providing valuable comments. 10. Contributing Authors Tarek Saad Cisco Systems Email: tsaad@cisco.com Siva Sivabalan Cisco Systems Email: msiva@cisco.com Akiya, et al. Expires February 2, 2015 [Page 6] Internet-Draft Seamless BFD for IP August 2014 Nagendra Kumar Cisco Systems Email: naikumar@cisco.com 11. References 11.1. Normative References [I-D.ietf-bfd-seamless-base] Akiya, N., Pignataro, C., Ward, D., Bhatia, M., and J. Networks, "Seamless Bidirectional Forwarding Detection (S-BFD)", draft-ietf-bfd-seamless-base-01 (work in progress), June 2014. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC5880] Katz, D. and D. Ward, "Bidirectional Forwarding Detection (BFD)", RFC 5880, June 2010. 11.2. Informative References [RFC2827] Ferguson, P. and D. Senie, "Network Ingress Filtering: Defeating Denial of Service Attacks which employ IP Source Address Spoofing", BCP 38, RFC 2827, May 2000. Authors' Addresses Nobo Akiya Cisco Systems Email: nobo@cisco.com Carlos Pignataro Cisco Systems Email: cpignata@cisco.com Dave Ward Cisco Systems Email: wardd@cisco.com Akiya, et al. Expires February 2, 2015 [Page 7]