Internet DRAFT - draft-eastlake-lldp-mac
draft-eastlake-lldp-mac
Network Working Group D. Eastlake
Internet-Draft Futurewei Technologies
Intended status: Standards Track 25 December 2023
Expires: 27 June 2024
MAC Address for Layer 3 Link Local Discovery Protocol (LLDP)
draft-eastlake-lldp-mac-01
Abstract
IEEE 802 has defined a number of protocols which can operate between
adjacent Ethernet stations at Layer 2, including bridges, and may be
useful between Layer 3 aware stations such as IP routers and hosts.
An example is the Link Layer Discover Protocol (IEEE Std 802.1AB,
LLDP). This document specifies a MAC address that can be used for
this purpose for interoperability despite intervening bridges.
Status of This Memo
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This Internet-Draft will expire on 27 June 2024.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Notations Used in This Document . . . . . . . . . . . . . 2
2. Network Layers and MAC Addresses . . . . . . . . . . . . . . 3
3. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
4. Security Considerations . . . . . . . . . . . . . . . . . . . 5
5. Normative References . . . . . . . . . . . . . . . . . . . . 5
6. Informative References . . . . . . . . . . . . . . . . . . . 5
Appendix A. EUI-48 Assignment Request . . . . . . . . . . . . . 6
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 7
1. Introduction
IEEE 802 [IEEE802] has defined a number of protocols which operate
between adjacent Ethernet stations at Layer 2, including bridges,
such as the Link Layer Discover Protocol ([IEEE802.1AB] LLDP) and the
Link Aggregation Control Protocol ([IEEE802.1AX] LACP). LLDP and
other such protocols may be useful between adjacent Layer 3 [ISO]
aware stations such as IP routers and hosts. This document specifies
a MAC address that can be used for that purpose despite intervening
bridges.
1.1. Notations Used in This Document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
In this document the terms/acronyms listed below have the indicated
meaning:
"LACP" Link Aggregation Control Protocol [IEEE802.1AX].
"Layer 2" Layer 2 in the ISO model [ISO].
"Layer 3" Layer 3 in the ISO model [ISO].
"LLDP" Link Layer Discovery Protocol [IEEE802.1AB].
"MAC" Media Access Control [RFC7042bis] (not Message Authentication
Code).
"PDU" Protocol Data Unit.
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2. Network Layers and MAC Addresses
LLDP [IEEE802.1AB] is a Layer 2 [ISO] protocol providing for the
unacknowledged announcement of information by an Ethernet station to
other stations on the same Ethernet link. There are proposals for
the use of LLDP between L3 aware stations such as between a host and
its first hop IP router or between IP adjacent routers. Examples are
[LLDP1] [LLDP2] [LLDP3].
As illustrated in the figure below, uses of LLDP and similar
protocols between Ethernet stations have a scope of adjacency
controlled by the multicast destination MAC address [RFC7042bis] of
the Ethernet frame used to transmit the LLDP PDU.
* Customer bridges use 0x0180C2000000 for LLDP and the like. Frames
sent to that address are transparently forwarded through any lower
level bridges, such as the provider bridges shown below. On the
other hand, IP routers do not forward frames sent to unknown
multicast addresses unless configured to do so. Thus, frames sent
to this address by the customer bridge shown near the bottom of
the figure will not reach either of the customer bridges shown
higher up in the figure due to the intervening IP router.
* Provider bridges use 0x0180C2000008 for LLDP. Frames sent to that
address are transparently forwarded by lower level bridges (not
shown in the figure) and are blocked by higher level bridges, such
as customer bridges. They are also blocked as described in the
previous point by IP routers.
LLDP or similar Ethernet frames intended to be between adjacent IP
routers or between a host and its first hop IP router need to avoid
use of a destination MAC address that might be intercepted by any
intervening bridge. The multicast destination MAC addresses used by
bridges are the block from 0x0180C2000000 to 0x0180C200003F but it
would be best to be conservative and avoid all addresses from
0x0180C2000000 to 0x0180C2FFFFFF. An address meeting this criterion
is specified in Section 3 below and its use is RECOMMENDED.
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+-------+
| Host |
+-------+
|
+---------+
|L3 Router|
+---------+
. \
. +---------------+
. |Customer Bridge|
. +---------------+
. : \
. : +---------------+
. : |Provider Bridge|
. : +---------------+
. : |
. : +---------------+
. : |Provider Bridge|
. : +---------------+
. : /
. +---------------+
. |Customer Bridge|
. +---------------+
. /
+---------+
|L3 Router|
+---------+
. \
. +---------------+
. |Customer Bridge|
. +---------------+
. /
+-------+
| Host |
+-------+
Figure 1: Geneve Header
Note: The above figure is simplified. For example, where one or
two customer bridges or provider bridges are shown, there could be
zero or some larger number. There could also be one or more
bridges between the host shown at the top of the figure and its
first hop IP router. Only two levels of bridge are shown
(customer and provider) but [IEEE802.1Q] specifies additional
levels of bridges.
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3. IANA Considerations
IANA is requested to assign a 48-bit multicast MAC address
[0x00000E900004 suggested] under the IANA OUI for use with Link Layer
Discovery Protocol and similar protocols between Layer 3 routers as
per the request in Appendix A. The entry in the "IANA Multicast
48-bit MAC Addresses" registry is as follows:
Addresses Usage Reference
--------- ------------------------- ---------------
[tbd] Layer 3 LLDP and the like [this document]
(Alternatively, there could be more than on MAC address assigned for
different L3 or higher layer [ISO] purposes.)
4. Security Considerations
TBD
5. Normative References
[IEEE802.1AB]
802, IEEE., "IEEE Standard for Local and metropolitan area
networks - Station and Media Access Control Connectivity
Discovery", IEEE Std 802.1AB-2016, 29 January 2016.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC7042bis]
Eastlake 3rd, D., Abley, J.N., and Y. Li, "IANA
Considerations and IETF Protocol and Documentation Usage
for IEEE 802 Parameters", Work in progress, 6 November
2023, <https://datatracker.ietf.org/doc/draft-ietf-
intarea-rfc7042bis/>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
6. Informative References
[IEEE802.1AX]
802, IEEE., "IEEE Standard for Local and metropolitan area
networks - Link Aggregation", IEEE Std 802.1AX-2014.
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[IEEE802.1Q]
802.1 WG, IEEE., "Bridges and Bridged Networks", IEEE Std
802.1Q-2014, 3 November 2014.
[IEEE802] 802, IEEE., "IEEE 802 LAN/MAN Standards Committee", IEEE
Std 802, <http://www.ieee802.org>.
[ISO] ISO/IEC, "Information technology - Open Systems
Interconnection - Basic Reference Model: The Basic Model",
ISO/IEC 7498-1:1994(E), 15 June 1996.
[LLDP1] Lindem, A., Patel, K., Zandi, S., Haas, J., and X. Xu,
"BGP Logical Link Discovery Protocol (LLDP) Peer
Discovery", Work in progress,
<https://datatracker.ietf.org/doc/draft-acee-idr-lldp-
peer-discovery/>.
[LLDP2] Congdon, P. and P. Bottorff, "LSVR IETF Organizationally
Specific TLVs for IEEE Std 802.1AB (LLDP)", work
in progress, <https://datatracker.ietf.org/doc/draft-
congdon-lsvr-lldp-tlvs/>.
[LLDP3] Richardson, M. and L. Xia, "Autonomic Control Plane design
for Layer-Two Switched Networks", Work in progress,
<https://datatracker.ietf.org/doc/draft-richardson-anima-
l2-friendly-acp/>.
Appendix A. EUI-48 Assignment Request
(not yet submitted)
Applicant Name: Donald E. Eastlake III
Applicant Email: d3e3e3@gmail.com
Applicant Telephone: +1-508-333-2270
Use Name: L3-LLDP
Document: [this document]
Specify whether this is an application for EUI-48 or EUI-64
identifiers: EUI-48
Size of Block requested: 1
Specify multicast, unicast, or both: multicast
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Author's Address
Donald E. Eastlake 3rd
Futurewei Technologies
2386 Panoramic Circle
Apopka, Florida 32703
United States of America
Phone: +1-508-333-2270
Email: d3e3e3@gmail.com
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