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Versions: 00 01 02 03 04 05 draft-ietf-bfd-seamless-ip

Internet Engineering Task Force                                 N. Akiya
Internet-Draft                                              C. Pignataro
Intended status: Standards Track                                 D. Ward
Expires: February 24, 2015                                 Cisco Systems
                                                         August 23, 2014


        Seamless Bidirectional Forwarding Detection (S-BFD) for
                          IPv4, IPv6 and MPLS
                     draft-akiya-bfd-seamless-ip-05

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 24, 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



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   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 Control Packet Demultiplexing . . . . . . . . . . . . .   3
   5.  Initiator Procedures  . . . . . . . . . . . . . . . . . . . .   3
     5.1.  Details of S-BFD Control 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 Control 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 control packets on the port TBD1.  SBFDInitiator
   sessions MUST transmit S-BFD control packets with destination port
   TBD1.  The source port of the S-BFD control packets transmitted by
   SBFDInitiator sessions can be of any but MUST NOT be TBD1.  The same
   UDP source port number MUST be used for all S-BFD control packets
   associated with a particular SBFDInitiator session.  The source port
   number MAY be unique among all SBFDInitiator sessions on the system.



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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.  SBFDInitiator sessions MUST
   transmit S-BFD echo packets with destination port TBD2.  This
   document defines only the UDP port value for the S-BFD Echo function.
   The source port and the procedures for the S-BFD Echo function are
   outside the scope of this document.

4.  S-BFD Control 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 control packets are transmitted with IP header, UDP header and
   BFD control header ([RFC5880]).  When S-BFD control 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 control packets.

5.1.  Details of S-BFD Control Packet Sent by SBFDInitiator

   o  Specifications common to both IP routed S-BFD control packets and
      explicitly label switched S-BFD control packets:

      *  Source IP address field of the IP header MUST be set to a local
         IP address that is expected to be routable by the target (i.e.
         not IPv6 link-local address when the target is multiple hops
         away).





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      *  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 that is not TBD1.

   o  Specifications for IP routed S-BFD control 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 control
      packets:

      *  S-BFD control 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 control 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 control packets not be dropped by the
   responder node due to TTL expiry.  Thus implementations on the
   responder MUST allow received S-BFD control packets taking TTL expiry
   exception path to reach corresponding reflector BFD session.

6.  Responder Procedures

   S-BFD control packets are IP routed back to the initiator, and will
   have IP header, UDP header and BFD control header.  If an
   SBFDReflector receives an S-BFD control packet with UDP source port
   as TBD1, the packet MUST be discarded.  Necessary values in the BFD



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   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
   control packets.

6.1.  Details of S-BFD Control 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 control packet.

   o  Source IP address field of the IP header MUST be set to a local IP
      address that is expected to be visible by the initiator (i.e. not
      IPv6 link-local address when the initiator is multiple hops away).

   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 control packets: [RFC2827].

   o  Implementations MUST NOT act on received S-BFD control packets
      containing Martian addresses as source IP addresses.

   o  Implementations MUST ensure that response S-BFD control 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:










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     Service Name (REQUIRED)
       s-bfd
     Transport Protocol(s) (REQUIRED)
       udp
     Assignee (REQUIRED)
       IESG <iesg@ietf.org>
     Contact (REQUIRED)
       BFD Chairs <bfd-chairs@tools.ietf.org>
     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 <iesg@ietf.org>
     Contact (REQUIRED)
       BFD Chairs <bfd-chairs@tools.ietf.org>
     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




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   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-02 (work in
              progress), August 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







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