< draft-dlep-lid-01.txt   draft-dlep-lid-02.txt >
Mobile Ad hoc Networks Working Group R. Taylor Mobile Ad hoc Networks Working Group R. Taylor
Internet-Draft Airbus Defence & Space Internet-Draft Airbus Defence & Space
Intended status: Standards Track July 20, 2017 Intended status: Standards Track S. Ratliff
Expires: January 21, 2018 Expires: May 15, 2018 VT iDirect
November 11, 2017
Link Identifier Extension to DLEP Link Identifier Extension to DLEP
draft-dlep-lid-01 draft-dlep-lid-02
Abstract Abstract
There exists a class of modems that wish to support the Dynamic Link There exists a class of modems that wish to support the Dynamic Link
Exchange Protocol (DLEP) [RFC8175] but do not present a single Layer Exchange Protocol (DLEP) [RFC8175] but do not present a single Layer
2 network domain as required by DLEP. Such devices may be: 2 network domain as required by DLEP. Such devices may be:
o Modems that maintain a varying link to some upstream backbone o Modems that maintain a varying link to some upstream backbone
network infrastructure, where the ability to announce link state network infrastructure, where the ability to announce link state
and DLEP metrics is desired, but the concept of a DLEP destination and DLEP metrics is desired, but the concept of a DLEP destination
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Copyright Notice Copyright Notice
Copyright (c) 2017 IETF Trust and the persons identified as the Copyright (c) 2017 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
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include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
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described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Requirements . . . . . . . . . . . . . . . . . . . . . . 3 1.1. Requirements . . . . . . . . . . . . . . . . . . . . . . 3
2. Operation . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Operation . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.1. Identifier Restrictions . . . . . . . . . . . . . . . . . 4 2.1. Identifier Restrictions . . . . . . . . . . . . . . . . . 4
2.2. Link Identifier Data Item . . . . . . . . . . . . . . . . 4 2.2. Negotiation . . . . . . . . . . . . . . . . . . . . . . . 4
3. Security Considerations . . . . . . . . . . . . . . . . . . . 5 3. Link Identifier Data Item . . . . . . . . . . . . . . . . . . 5
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5 4. Security Considerations . . . . . . . . . . . . . . . . . . . 5
4.1. DLEP Link Identifier Flag . . . . . . . . . . . . . . . . 5 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
5. References . . . . . . . . . . . . . . . . . . . . . . . . . 6 5.1. DLEP Link Identifier Flag . . . . . . . . . . . . . . . . 6
5.1. Normative References . . . . . . . . . . . . . . . . . . 6 6. References . . . . . . . . . . . . . . . . . . . . . . . . . 6
5.2. Informative References . . . . . . . . . . . . . . . . . 6 6.1. Normative References . . . . . . . . . . . . . . . . . . 6
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 6 6.2. Informative References . . . . . . . . . . . . . . . . . 6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7
1. Introduction 1. Introduction
The Dynamic Link Exchange Protocol (DLEP) [RFC8175] describes a The Dynamic Link Exchange Protocol (DLEP) [RFC8175] describes a
protocol for modems to advertise the status of wireless links between protocol for modems to advertise the status of wireless links between
reachable destinations to attached routers. The core specification reachable destinations to attached routers. The core specification
of the protocol assumes that every modem in the radio network has an of the protocol assumes that every modem in the radio network has an
attached DLEP router, and the MAC address of the DLEP interface on attached DLEP router, and requires that the MAC address of the DLEP
the router is used to identify the destination in the network for interface on the attached router is used to identify the destination
purposes of reporting the state and quality of the link to that in the network for purposes of reporting the state and quality of the
destination. link to that destination.
This document describes a DLEP Extension allowing modems that do not This document describes a DLEP Extension allowing modems that do not
meet the strict requirement that DLEP must be implemented on a single meet the strict requirement that DLEP must be implemented on a single
Layer 2 domain to use DLEP to describe link state and quality to one Layer 2 domain to use DLEP to describe link availability and quality
or more destinations reachable only at Layer 3. to one or more destinations reachable beyond a local or remote device
on the Layer 2 domain. A router can use this knowledge to influence
any routing or flow-control decisions regarding traffic to this
destination, understanding that such traffic flows via Layer 3.
To enable routers to take advantage of the DLEP protocol this A Layer 3 destination may be an attached DLEP router, in the case of
extension adds a single enhancement to the DLEP protocol: A new Link a modem that provides Layer 3 wide area network connectivity between
Identifier Data Item. This Data Item replaces the use of the MAC devices, or a logical destination that describes a set of attached
Address Data Item whenever the DLEP destination does not have a subnets, when referring to some upstream backbone network
router reachable by MAC address. infrastructure.
By using the Link Identifier Data Item, the modem implementation can To enable devices to take advantage of the DLEP protocol this
announce the link state and quality to a uniquely identified extension adds a single enhancement: A new Link Identifier Data Item
destination in the network, either logical or physical, explicitly (Section 3).
indicating that the destination is not reachable via a single Layer 2
domain. A router can use this knowledge to influence any routing or
flow-control decisions regarding traffic to this destination,
understanding that such decisions apply at Layer 3.
1.1. Requirements 1.1. Requirements
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in BCP 14, RFC 2119 document are to be interpreted as described in BCP 14, RFC 2119
[RFC2119]. [RFC2119].
2. Operation 2. Operation
To refer to a Layer 3 DLEP Destination, the DLEP session participant
adds a Link Identifier Data Item (Section 3) to the relevant
Destination Message, and (as usual) includes a MAC Address Data Item.
When paired with a Link Identifier Data Item, the MAC Address Data
Item describes the MAC address of the node in the network beyond
which the Layer 3 DLEP Destination resides. The MAC address MAY
belong to the DLEP peer modem, if the over-the-air network is not a
single Layer 2 domain, or MAY be the MAC address of a remote node in
the Layer 2 domain that has indicated that it has DLEP Destinations
reachable beyond it. How such remote destinations are discovered is
beyond the scope of this specification.
As only modems are initially aware of Layer 3 DLEP Destinations, Link
Identifier Data Items referring to a new link MUST first appear in a
DLEP Destination Up Message from the modem to the router. Once a
link has been identified in this way, Link Identifier Data Items MAY
be used by either DLEP participant during the lifetime of a DLEP
session. Because of this, a router MUST NOT send a DLEP Destination
Announce Message containing a Link Identifier Data Item referring to
a link that has not been mentioned in a prior DLEP Destination Up
Message.
Because the MAC Address associated with any DLEP Destination Message
containing a Link Identifier Data Item is not the Layer 2 address of
the destination, all DLEP Destination Up Messages MUST contain Layer
3 information. In the case of modems that provide Layer 3 wide area
network connectivity between devices, this means one or more IPv4 or
IPv6 Address Data Items providing the Layer 3 address of the
destination. When referring to some upstream backbone network
infrastructure, this means one or more IPv4 or IPv6 Attached Subnet
Data Items, for example: '0.0.0.0/0' or '::/0'. This allows the DLEP
peer router to understand the properties of the link to those routes.
When the DLEP peer router wishes to forward packets to the Layer 3
destination or subnet, the MAC address associated with the link MUST
be used as the Layer 2 destination of the packet.
2.1. Identifier Restrictions
A Link identifier is 4 octets in length. The method for generating
identifiers is a modem implementation matter and out of scope of this
document. Routers MUST NOT make any assumptions about the meaning of
identifiers, or how identifiers are generated.
Within a single DLEP session, all link identifiers MUST be unique per
MAC Address. This means that a Layer 3 DLEP Destination is uniquely
identified by the pair: {MAC Address,Link Id}.
Identifiers MUST NOT be reused, i.e. a {MAC Address,Link Id} pair
that has been used to refer to one destination MUST NOT be recycled
to refer to a different destination within the lifetime of a single
DLEP session.
2.2. Negotiation
To use this extension, as with all DLEP extensions, the extension To use this extension, as with all DLEP extensions, the extension
MUST be announced during DLEP session initialization. A router MUST be announced during DLEP session initialization. A router
advertises support by including the value 'Link Identitifers' (TBD1) advertises support by including the value 'Link Identifiers' (TBD1),
in the Extension Data Item within the Session Intitialization Section 5, in the Extension Data Item within the Session
Message. A modem advertises support by including the value 'Link Initialization Message. A modem advertises support by including the
Identitifers' (TBD1) in the Extension Data Item within the Session value 'Link Identifiers' (TBD1) in the Extension Data Item within the
Intitialization Response Message. If both DLEP peers advertise Session Initialization Response Message. If both DLEP peers
support for this extension then the Link Identifier Data Item MAY be advertise support for this extension then the Link Identifier Data
used. Item MAY be used.
If a modem requires support for this extension in order to describe If a modem requires support for this extension in order to describe
destinations, and the router does not advertise support, then the destinations, and the router does not advertise support, then the
modem MUST NOT include a Link Identifier Data Item in any DLEP modem MUST NOT include a Link Identifier Data Item in any DLEP
Message. However, the modem SHOULD NOT immediately terminate the Message. However, the modem SHOULD NOT immediately terminate the
DLEP session, rather it should use session-wide DLEP Data Items to DLEP session, rather it SHOULD use session-wide DLEP Data Items to
announce general information about all reachable destinations via the announce general information about all reachable destinations via the
modem. By doing this, a modem allows a router not supporting this modem. By doing this, a modem allows a router not supporting this
extension to at least make a best guess at the state of any reachable extension to at least make a best guess at the state of any reachable
network. A modem MUST NOT attempt to re-use the MAC Address Data network. A modem MUST NOT attempt to re-use the MAC Address Data
Item to perform some kind of sleight-of-hand, assuming that the Item to perform some kind of sleight-of-hand, assuming that the
router will notice the DLEP Peer Type of the modem is special in some router will notice the DLEP Peer Type of the modem is special in some
way. way.
Even when the Link Identifiers extension is in use for a DLEP 3. Link Identifier Data Item
session, both peers MUST support sending and receiving Messages
concerning DLEP destinations using the standard DLEP MAC Address Data
Item, as the use of this extension does not alter the representation
of multicast logical destinations.
2.1. Identifier Restrictions
Within a single DLEP session, all identifiers used by this extension,
both logical and physical, MUST be unique, and MUST be of the same
octet length as the MAC address of the interface in use for the DLEP
session, as per MAC Address Data Items. This removes the need for an
extra LID length negotiation step during Session Initialization.
Identifiers MUST NOT be reused, i.e. an indentifier that has been
used to refer to one destination MUST NOT be recycled to refer to a
different destination within the lifetime of a single DLEP session.
The method for generating identifiers is a modem implementation
matter and out of scope of this document. Routers MUST NOT make any
assumptions about the meaning of identifiers, or how identifiers are
generated.
Router implementations MUST NOT assume that LIDs will not clash with
any MAC Address Data Items also in use during the DLEP session, LIDs
exist in a separate numbering space.
2.2. Link Identifier Data Item
The Link Identifier Data Item MAY be used whenever a MAC Address Data The Link Identifier Data Item MAY be used wherever a MAC Address Data
Item is defined as useable in core DLEP. A single Link Identifier Item is defined as usable in core DLEP.
Data Item MUST only be used in place of a single MAC Address Data
Item. A Link Identifier Data Item MUST NOT appear in the same DLEP
Message as a MAC Address Data Item.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Data Item Type | Length | | Data Item Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flags | Link Identifier... : | Flags | Link Identifier... :
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Data Item Type: TBD2 Data Item Type: TBD2, Section 5
Length: Same as the MAC Address Data Item in use by the session. Length: 5
Flags: Flags field, defined below. Flags: Flags field, defined below.
Link Identifier: The unique identifier of the link destination. Link Identifier: The 4 octet unique identifier of the Layer 3
This identifier has no implicit meaning and is only used to destination. This identifier has no implicit meaning and is only
discriminate between multiple links. used to discriminate between multiple links.
The Flags field is defined as: The Flags field is defined as:
0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
| Reserved | | Reserved |
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
Reserved: MUST be zero. Left for future assignment. Reserved: MUST be zero. Left for future assignment.
3. Security Considerations 4. Security Considerations
As an extension to the core DLEP protocol, the security As an extension to the core DLEP protocol, the security
considerations of that protocol apply to this extension. This considerations of that protocol apply to this extension. This
extension adds no additional security mechanisms or features. extension adds no additional security mechanisms or features.
None of the features introduced by this extension require extra None of the features introduced by this extension require extra
consideration by an implementation. consideration by an implementation.
4. IANA Considerations 5. IANA Considerations
Upon approval of this document, IANA is requested to: Upon approval of this document, IANA is requested to:
o Assign a new value (TBD1) from the Specification Required section o Assign a new value (TBD1) from the Specification Required section
of the DLEP Extensions Registry, named "Link Identifiers". of the DLEP Extensions Registry, named "Link Identifiers".
o Assign a new value (TBD2) from the Specification Required section o Assign a new value (TBD2) from the Specification Required section
of the DLEP Data Item Type Values Registry, named "Link of the DLEP Data Item Type Values Registry, named "Link
Identifier". Identifier".
4.1. DLEP Link Identifier Flag 5.1. DLEP Link Identifier Flag
Upon approval of this document, IANA is requested to create a new Upon approval of this document, IANA is requested to create a new
DLEP registry, named "Link Identifier Flags". DLEP registry, named "Link Identifier Flags".
The following table provides initial registry values and the The following table provides initial registry values and the
[RFC5226] defined policies that should apply to the registry: [RFC5226] defined policies that should apply to the registry:
+------------+------------------------------------+ +------------+------------------------------------+
| Bit | Description/Policy | | Bit | Description/Policy |
+------------+------------------------------------+ +------------+------------------------------------+
| 0-7 | Unassigned/Specification Required | | 0-7 | Unassigned/Specification Required |
+------------+------------------------------------+ +------------+------------------------------------+
5. References 6. References
5.1. Normative References 6.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997, <https://www.rfc-
<http://www.rfc-editor.org/info/rfc2119>. editor.org/info/rfc2119>.
[RFC8175] Ratliff, S., Jury, S., Satterwhite, D., Taylor, R., and B. [RFC8175] Ratliff, S., Jury, S., Satterwhite, D., Taylor, R., and B.
Berry, "Dynamic Link Exchange Protocol (DLEP)", RFC 8175, Berry, "Dynamic Link Exchange Protocol (DLEP)", RFC 8175,
DOI 10.17487/RFC8175, June 2017, DOI 10.17487/RFC8175, June 2017, <https://www.rfc-
<http://www.rfc-editor.org/info/rfc8175>. editor.org/info/rfc8175>.
5.2. Informative References 6.2. Informative References
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", RFC 5226, IANA Considerations Section in RFCs", RFC 5226,
DOI 10.17487/RFC5226, May 2008, DOI 10.17487/RFC5226, May 2008, <https://www.rfc-
<http://www.rfc-editor.org/info/rfc5226>. editor.org/info/rfc5226>.
Author's Address Authors' Addresses
Rick Taylor Rick Taylor
Airbus Defence & Space Airbus Defence & Space
Quadrant House Quadrant House
Celtic Springs Celtic Springs
Coedkernew Coedkernew
Newport NP10 8FZ Newport NP10 8FZ
UK UK
Email: rick.taylor@airbus.com Email: rick.taylor@airbus.com
Stan Ratliff
VT iDirect
13861 Sunrise Valley Drive, Suite 300
Herndon, VA 20171
USA
Email: sratliff@idirect.net
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