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Is this intentional? Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) -- Obsolete informational reference (is this intentional?): RFC 5226 (Obsoleted by RFC 8126) Summary: 1 error (**), 0 flaws (~~), 1 warning (==), 2 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Mobile Ad hoc Networks Working Group R. Taylor 3 Internet-Draft Airbus Defence & Space 4 Intended status: Standards Track S. Ratliff 5 Expires: May 15, 2018 VT iDirect 6 November 11, 2017 8 Link Identifier Extension to DLEP 9 draft-dlep-lid-02 11 Abstract 13 There exists a class of modems that wish to support the Dynamic Link 14 Exchange Protocol (DLEP) [RFC8175] but do not present a single Layer 15 2 network domain as required by DLEP. Such devices may be: 17 o Modems that maintain a varying link to some upstream backbone 18 network infrastructure, where the ability to announce link state 19 and DLEP metrics is desired, but the concept of a DLEP destination 20 router for the backbone does not apply. Examples of such devices 21 can include LTE modems, IEEE 802.11 stations not in ad-hoc mode, 22 and some satellite terminals. 24 o Modems that provide Layer 3 wide area network connectivity between 25 devices, where individual DLEP destinations do exist, but are not 26 directly reachable by MAC address. 28 This document introduces an optional extension to the core DLEP 29 specification, allowing DLEP to be used between routers and modems 30 that operate in this way. 32 Note: 34 o This document is intended as an extension to the core DLEP 35 specification, and readers are expected to be fully conversant 36 with the operation of core DLEP. 38 Status of This Memo 40 This Internet-Draft is submitted in full conformance with the 41 provisions of BCP 78 and BCP 79. 43 Internet-Drafts are working documents of the Internet Engineering 44 Task Force (IETF). Note that other groups may also distribute 45 working documents as Internet-Drafts. The list of current Internet- 46 Drafts is at http://datatracker.ietf.org/drafts/current/. 48 Internet-Drafts are draft documents valid for a maximum of six months 49 and may be updated, replaced, or obsoleted by other documents at any 50 time. It is inappropriate to use Internet-Drafts as reference 51 material or to cite them other than as "work in progress." 53 This Internet-Draft will expire on May 15, 2018. 55 Copyright Notice 57 Copyright (c) 2017 IETF Trust and the persons identified as the 58 document authors. All rights reserved. 60 This document is subject to BCP 78 and the IETF Trust's Legal 61 Provisions Relating to IETF Documents 62 (http://trustee.ietf.org/license-info) in effect on the date of 63 publication of this document. Please review these documents 64 carefully, as they describe your rights and restrictions with respect 65 to this document. Code Components extracted from this document must 66 include Simplified BSD License text as described in Section 4.e of 67 the Trust Legal Provisions and are provided without warranty as 68 described in the Simplified BSD License. 70 Table of Contents 72 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 73 1.1. Requirements . . . . . . . . . . . . . . . . . . . . . . 3 74 2. Operation . . . . . . . . . . . . . . . . . . . . . . . . . . 3 75 2.1. Identifier Restrictions . . . . . . . . . . . . . . . . . 4 76 2.2. Negotiation . . . . . . . . . . . . . . . . . . . . . . . 4 77 3. Link Identifier Data Item . . . . . . . . . . . . . . . . . . 5 78 4. Security Considerations . . . . . . . . . . . . . . . . . . . 5 79 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 80 5.1. DLEP Link Identifier Flag . . . . . . . . . . . . . . . . 6 81 6. References . . . . . . . . . . . . . . . . . . . . . . . . . 6 82 6.1. Normative References . . . . . . . . . . . . . . . . . . 6 83 6.2. Informative References . . . . . . . . . . . . . . . . . 6 84 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7 86 1. Introduction 88 The Dynamic Link Exchange Protocol (DLEP) [RFC8175] describes a 89 protocol for modems to advertise the status of wireless links between 90 reachable destinations to attached routers. The core specification 91 of the protocol assumes that every modem in the radio network has an 92 attached DLEP router, and requires that the MAC address of the DLEP 93 interface on the attached router is used to identify the destination 94 in the network for purposes of reporting the state and quality of the 95 link to that destination. 97 This document describes a DLEP Extension allowing modems that do not 98 meet the strict requirement that DLEP must be implemented on a single 99 Layer 2 domain to use DLEP to describe link availability and quality 100 to one or more destinations reachable beyond a local or remote device 101 on the Layer 2 domain. A router can use this knowledge to influence 102 any routing or flow-control decisions regarding traffic to this 103 destination, understanding that such traffic flows via Layer 3. 105 A Layer 3 destination may be an attached DLEP router, in the case of 106 a modem that provides Layer 3 wide area network connectivity between 107 devices, or a logical destination that describes a set of attached 108 subnets, when referring to some upstream backbone network 109 infrastructure. 111 To enable devices to take advantage of the DLEP protocol this 112 extension adds a single enhancement: A new Link Identifier Data Item 113 (Section 3). 115 1.1. Requirements 117 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 118 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 119 document are to be interpreted as described in BCP 14, RFC 2119 120 [RFC2119]. 122 2. Operation 124 To refer to a Layer 3 DLEP Destination, the DLEP session participant 125 adds a Link Identifier Data Item (Section 3) to the relevant 126 Destination Message, and (as usual) includes a MAC Address Data Item. 127 When paired with a Link Identifier Data Item, the MAC Address Data 128 Item describes the MAC address of the node in the network beyond 129 which the Layer 3 DLEP Destination resides. The MAC address MAY 130 belong to the DLEP peer modem, if the over-the-air network is not a 131 single Layer 2 domain, or MAY be the MAC address of a remote node in 132 the Layer 2 domain that has indicated that it has DLEP Destinations 133 reachable beyond it. How such remote destinations are discovered is 134 beyond the scope of this specification. 136 As only modems are initially aware of Layer 3 DLEP Destinations, Link 137 Identifier Data Items referring to a new link MUST first appear in a 138 DLEP Destination Up Message from the modem to the router. Once a 139 link has been identified in this way, Link Identifier Data Items MAY 140 be used by either DLEP participant during the lifetime of a DLEP 141 session. Because of this, a router MUST NOT send a DLEP Destination 142 Announce Message containing a Link Identifier Data Item referring to 143 a link that has not been mentioned in a prior DLEP Destination Up 144 Message. 146 Because the MAC Address associated with any DLEP Destination Message 147 containing a Link Identifier Data Item is not the Layer 2 address of 148 the destination, all DLEP Destination Up Messages MUST contain Layer 149 3 information. In the case of modems that provide Layer 3 wide area 150 network connectivity between devices, this means one or more IPv4 or 151 IPv6 Address Data Items providing the Layer 3 address of the 152 destination. When referring to some upstream backbone network 153 infrastructure, this means one or more IPv4 or IPv6 Attached Subnet 154 Data Items, for example: '0.0.0.0/0' or '::/0'. This allows the DLEP 155 peer router to understand the properties of the link to those routes. 157 When the DLEP peer router wishes to forward packets to the Layer 3 158 destination or subnet, the MAC address associated with the link MUST 159 be used as the Layer 2 destination of the packet. 161 2.1. Identifier Restrictions 163 A Link identifier is 4 octets in length. The method for generating 164 identifiers is a modem implementation matter and out of scope of this 165 document. Routers MUST NOT make any assumptions about the meaning of 166 identifiers, or how identifiers are generated. 168 Within a single DLEP session, all link identifiers MUST be unique per 169 MAC Address. This means that a Layer 3 DLEP Destination is uniquely 170 identified by the pair: {MAC Address,Link Id}. 172 Identifiers MUST NOT be reused, i.e. a {MAC Address,Link Id} pair 173 that has been used to refer to one destination MUST NOT be recycled 174 to refer to a different destination within the lifetime of a single 175 DLEP session. 177 2.2. Negotiation 179 To use this extension, as with all DLEP extensions, the extension 180 MUST be announced during DLEP session initialization. A router 181 advertises support by including the value 'Link Identifiers' (TBD1), 182 Section 5, in the Extension Data Item within the Session 183 Initialization Message. A modem advertises support by including the 184 value 'Link Identifiers' (TBD1) in the Extension Data Item within the 185 Session Initialization Response Message. If both DLEP peers 186 advertise support for this extension then the Link Identifier Data 187 Item MAY be used. 189 If a modem requires support for this extension in order to describe 190 destinations, and the router does not advertise support, then the 191 modem MUST NOT include a Link Identifier Data Item in any DLEP 192 Message. However, the modem SHOULD NOT immediately terminate the 193 DLEP session, rather it SHOULD use session-wide DLEP Data Items to 194 announce general information about all reachable destinations via the 195 modem. By doing this, a modem allows a router not supporting this 196 extension to at least make a best guess at the state of any reachable 197 network. A modem MUST NOT attempt to re-use the MAC Address Data 198 Item to perform some kind of sleight-of-hand, assuming that the 199 router will notice the DLEP Peer Type of the modem is special in some 200 way. 202 3. Link Identifier Data Item 204 The Link Identifier Data Item MAY be used wherever a MAC Address Data 205 Item is defined as usable in core DLEP. 207 0 1 2 3 208 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 1 209 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 210 | Data Item Type | Length | 211 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 212 | Flags | Link Identifier... : 213 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 215 Data Item Type: TBD2, Section 5 217 Length: 5 219 Flags: Flags field, defined below. 221 Link Identifier: The 4 octet unique identifier of the Layer 3 222 destination. This identifier has no implicit meaning and is only 223 used to discriminate between multiple links. 225 The Flags field is defined as: 227 0 1 2 3 4 5 6 7 228 +-+-+-+-+-+-+-+-+ 229 | Reserved | 230 +-+-+-+-+-+-+-+-+ 232 Reserved: MUST be zero. Left for future assignment. 234 4. Security Considerations 236 As an extension to the core DLEP protocol, the security 237 considerations of that protocol apply to this extension. This 238 extension adds no additional security mechanisms or features. 240 None of the features introduced by this extension require extra 241 consideration by an implementation. 243 5. IANA Considerations 245 Upon approval of this document, IANA is requested to: 247 o Assign a new value (TBD1) from the Specification Required section 248 of the DLEP Extensions Registry, named "Link Identifiers". 250 o Assign a new value (TBD2) from the Specification Required section 251 of the DLEP Data Item Type Values Registry, named "Link 252 Identifier". 254 5.1. DLEP Link Identifier Flag 256 Upon approval of this document, IANA is requested to create a new 257 DLEP registry, named "Link Identifier Flags". 259 The following table provides initial registry values and the 260 [RFC5226] defined policies that should apply to the registry: 262 +------------+------------------------------------+ 263 | Bit | Description/Policy | 264 +------------+------------------------------------+ 265 | 0-7 | Unassigned/Specification Required | 266 +------------+------------------------------------+ 268 6. References 270 6.1. Normative References 272 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 273 Requirement Levels", BCP 14, RFC 2119, 274 DOI 10.17487/RFC2119, March 1997, . 277 [RFC8175] Ratliff, S., Jury, S., Satterwhite, D., Taylor, R., and B. 278 Berry, "Dynamic Link Exchange Protocol (DLEP)", RFC 8175, 279 DOI 10.17487/RFC8175, June 2017, . 282 6.2. Informative References 284 [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an 285 IANA Considerations Section in RFCs", RFC 5226, 286 DOI 10.17487/RFC5226, May 2008, . 289 Authors' Addresses 291 Rick Taylor 292 Airbus Defence & Space 293 Quadrant House 294 Celtic Springs 295 Coedkernew 296 Newport NP10 8FZ 297 UK 299 Email: rick.taylor@airbus.com 301 Stan Ratliff 302 VT iDirect 303 13861 Sunrise Valley Drive, Suite 300 304 Herndon, VA 20171 305 USA 307 Email: sratliff@idirect.net