BFD Encapsulated in Large Packets
draft-ietf-bfd-large-packets-02
Network Working Group J. Haas
Internet-Draft Juniper Networks, Inc.
Intended status: Standards Track A. Fu
Expires: May 4, 2020 Bloomberg L.P.
November 1, 2019
BFD Encapsulated in Large Packets
draft-ietf-bfd-large-packets-02
Abstract
The Bidirectional Forwarding Detection (BFD) protocol is commonly
used to verify connectivity between two systems. BFD packets are
typically very small. It is desirable in some circumstances to know
that not only is the path between two systems reachable, but also
that it is capable of carrying a payload of a particular size. This
document discusses thoughts on how to implement such a mechanism
using BFD in Asynchronous mode.
Requirements Language
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 normative meaning.
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
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material or to cite them other than as "work in progress."
This Internet-Draft will expire on May 4, 2020.
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Copyright Notice
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document authors. All rights reserved.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. BFD Encapsulated in Large Packets . . . . . . . . . . . . . . 3
3. Implementation and Deployment Considerations . . . . . . . . 3
3.1. Implementations that do not support Large BFD Packets . . 3
3.2. Selecting MTU size to be detected . . . . . . . . . . . . 4
3.3. Detecting MTU mismatches . . . . . . . . . . . . . . . . 4
3.4. Equal Cost Multiple Paths (ECMP) or other Load Balancing
Considerations . . . . . . . . . . . . . . . . . . . . . 5
3.5. S-BFD . . . . . . . . . . . . . . . . . . . . . . . . . . 5
4. Security Considerations . . . . . . . . . . . . . . . . . . . 5
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 6
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 6
7.1. Normative References . . . . . . . . . . . . . . . . . . 6
7.2. Informative References . . . . . . . . . . . . . . . . . 7
Appendix A. Related Features . . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7
1. Introduction
The Bidirectional Forwarding Detection (BFD) [RFC5880] protocol is
commonly used to verify connectivity between two systems. However,
some applications may require that the Path MTU [RFC1191] between
those two systems meets a certain minimum criteria. When the Path
MTU decreases below the minimum threshold, those applications may
wish to consider the path unusable.
BFD may be encapsulated in a number of transport protocols. An
example of this is single-hop BFD [RFC5881]. In that case, the link
MTU configuration is typically enough to guarantee communication
between the two systems for that size MTU. BFD Echo mode
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(Section 6.4 of [RFC5880]) is sufficient to permit verification of
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