One document matched: draft-akiya-bfd-seamless-ip-04.txt
Differences from draft-akiya-bfd-seamless-ip-03.txt
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
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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 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.
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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. 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.
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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.
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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:
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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-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
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