DLEP Multi-Hop Forwarding Extension
draft-ietf-manet-dlep-multi-hop-extension-00
The information below is for an old version of the document.
Document | Type |
This is an older version of an Internet-Draft that was ultimately published as RFC 8629.
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Authors | Bow-Nan Cheng , Lou Berger | ||
Last updated | 2017-08-13 (Latest revision 2017-02-09) | ||
RFC stream | Internet Engineering Task Force (IETF) | ||
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Additional resources | Mailing list discussion | ||
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IESG | IESG state | Became RFC 8629 (Proposed Standard) | |
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draft-ietf-manet-dlep-multi-hop-extension-00
Network Working Group B. Cheng Internet-Draft Lincoln Laboratory Intended status: Standards Track L. Berger, Ed. Expires: August 13, 2017 LabN Consulting, L.L.C. February 9, 2017 DLEP Multi-Hop Forwarding Extension draft-ietf-manet-dlep-multi-hop-extension-00 Abstract This document defines an extension to the DLEP protocol that enables a the reporting and control of Multi-Hop Forwarding by DLEP capable modems. 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 August 13, 2017. Copyright Notice Copyright (c) 2017 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 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. Cheng & Berger Expires August 13, 2017 [Page 1] Internet-Draft DLEP Multi-Hop Extension February 2017 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1.1. Key Words . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Extension Usage and Identification . . . . . . . . . . . . . 3 3. Extension Data Items . . . . . . . . . . . . . . . . . . . . 3 3.1. Hop Count . . . . . . . . . . . . . . . . . . . . . . . . 3 3.2. Hop Control . . . . . . . . . . . . . . . . . . . . . . . 5 3.2.1. Reset . . . . . . . . . . . . . . . . . . . . . . . . 6 3.2.2. Terminate . . . . . . . . . . . . . . . . . . . . . . 6 3.2.3. Direct Connection . . . . . . . . . . . . . . . . . . 6 3.2.4. Suppress Forwarding . . . . . . . . . . . . . . . . . 7 4. Security Considerations . . . . . . . . . . . . . . . . . . . 7 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7 5.1. Extension Type Value . . . . . . . . . . . . . . . . . . 7 5.2. Data Item Values . . . . . . . . . . . . . . . . . . . . 8 5.3. Hop Control Actions Registry . . . . . . . . . . . . . . 8 6. References . . . . . . . . . . . . . . . . . . . . . . . . . 9 6.1. Normative References . . . . . . . . . . . . . . . . . . 9 6.2. Informative References . . . . . . . . . . . . . . . . . 9 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9 1. Introduction The Dynamic Link Event Protocol (DLEP) is defined in [I-D.ietf-manet-dlep]. It provides the exchange of link related control information between DLEP peers. DLEP peers are comprised of a modem and a router. DLEP defines a base set of mechanisms as well as support for possible extensions. This document defines one such extension. Some modem technologies support connectivity to destinations via multi-hop forwarding. DLEP Destination messages can be used to report such connectivity, see [I-D.ietf-manet-dlep], but do not provide any information related to the number or capacity of the hops. The extension defined in this document enables modems to inform routers when multi-hop forwarding is being used, and routers to request that modems change multi-hop forwarding behavior. The extension defined in this document is referred to as "Multi-Hop Forwarding". This document defines a new DLEP Extension Type Value in Section 2 which is used to indicate the use of the extension, and three new DLEP Data Items in Section 3. Cheng & Berger Expires August 13, 2017 [Page 2] Internet-Draft DLEP Multi-Hop Extension February 2017 1.1. Key Words 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, RFC 2119 [RFC2119]. 2. Extension Usage and Identification The use of the Multi-Hop Forwarding Extension SHOULD be configurable. To indicate that the extension is to be used, an implementation MUST include the Multi-Hop Forwarding Extension Type Value in the Extensions Supported Data Item. The Extensions Supported Data Item is sent and processed according to [I-D.ietf-manet-dlep]. The Multi-Hop Forwarding Extension Type Value is TBA1, see Section 5. 3. Extension Data Items Three data items are defined by this extension. The Hop Count Data Item is used by a modem to provide the number of network hops traversed to reach a particular destination. The Hop Control Data Item is used by a router to request that a modem alter connectivity to a particular destination. The Suppress Forwarding Data Item is used by a router to request that a modem disable multi-hop forwarding on either a device or destination basis. 3.1. Hop Count The Hop Count Data Item is used by a modem to indicate the number of physical hops between the modem and a specific destination. In other words, each hop represents a transmission and the number of hops is equal to the number of transmissions required to go from a router connected modem to the destination's connected modem. The minimum number of hops is 1, which represents the router's locally connected modem. The data item also contains an indication of when a destination which currently has a hop count of greater than one (1) could be made direcly reachable by a modem, e.g., by re-aiming an antenna. The Hop Count Data Item SHOULD be carried in the Destination Up, Destination Update, Destination Announce Response, and Link Characteristics Response Messages when the Hop Count to a destination is greater than one (1). A router receiving a Hop Count Data Item MAY use this information in its forwarding and routing decisions, and specific use is out of Cheng & Berger Expires August 13, 2017 [Page 3] Internet-Draft DLEP Multi-Hop Extension February 2017 scope of this document. The absence of the Hop Count Data Item MUST be interpreted by the router as a Hop Count value of one (1). The format of the Hop Count Data Item is: 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Data Item Type | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Hop Count |P| Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Data Item Type: TBA2 Length: 4 Hop Count: An unsigned 8-bit integer indicating the number of network hops required (i.e., number of times a packet will be transmitted) to reach the destination indicated in the message. The special value of 255 (0xFF) is used to indicate that the number of hops is an unknown number greater than one (1). This field MUST contain a value of at least one (1) if the associated destination is reachable. A value of zero (0) is used to indicated that processing of a Hop Control action, see Section 3.2, has resulted in a destination no longer being reachable. A zero value MUST NOT be used in any message other then a Destination Announce Response Message. P: The P-bit indicates that a destination is potentially directly reachable. When the P-bit is set, the router MAY request a direct link to the associated destination using the Hop Control Data Item described below. Reserved: MUST be set to zero by the sender (a modem) and ignored by the receiver (a router). Cheng & Berger Expires August 13, 2017 [Page 4] Internet-Draft DLEP Multi-Hop Extension February 2017 3.2. Hop Control The Hop Control Data Item is used by a router to request a change in connectivity to a particular destination, or in multi-hop processing on a device wide basis. A router can request multi-hop reachable destination be changed to a single hop. A router can also indicate that the modem terminate connectivity to a particular destination. The Hop Control Data Item MAY be carried in the Session Update Message or Destination Announce Message. A router that receives the Hop Control in a Session Update Message SHOULD attempt to make the change indicated by the data item for the whole device. Results of any changes made are reflected in Destination Down and Destination Update Messages. The modem MUST notify the router of each destination that is no longer reachable via a Destination Down Message. The modem MUST notify the router of any changes in Hop Counts via Destination Update Messages. A router that receives the Hop Control in a Destination Announce Message SHOULD attempt to make the change indicated by the data item for the associated destination MAC address. Once the change is made, or fails or is rejected, the modem MUST respond with a Destination Announce Response Message containing an updated Hop Count Data Item. The format of the Hop Control Data Item is: 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Data Item Type | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Hop Control Actions | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Data Item Type: TBA3 Length: 4 Hop Control Actions: An unsigned 16-bit value with the following meaning: Cheng & Berger Expires August 13, 2017 [Page 5] Internet-Draft DLEP Multi-Hop Extension February 2017 +-------+---------------------+ | Value | Action | +-------+---------------------+ | 0 | Reset | | | | | 1 | Terminate | | | | | 2 | Direct Connection | | | | | 3 | Suppress Forwarding | +-------+---------------------+ Table 1: Hop Control Actions Values 3.2.1. Reset The Reset Action requests that the default behavior be restored. When received in a Session Update Message message, a modem SHOULD clear all control actions that have previously been processed on a device wide basis, and revert to its configured behavior. When received in a Destination Announce Message, a modem SHOULD clear all control actions that have previously been processed for the destination indicated in the message. 3.2.2. Terminate The Terminate Action is only valid on a per destination basis and MUST NOT be sent in a Session Update Message message. It indicates that the modem SHOULD attempt to terminate communication with the destination identified in the message. This request has no impact for multi-hop destinations and may fail even in a single hop case, i.e. MAY result in the Hop Count to the destination not being impacted by the processing of the request 3.2.3. Direct Connection The Direct Connection is only valid on a per destination basis and MUST NOT be sent in a Session Update Message message. It indicates that the modem SHOULD attempt to establish a direct connection with the destination identified in the message. This action SHOULD only be sent for destinations for which the Hop Count is greater than 1 and has the P-Bit set in the previously received Hop Count Data Item. Results of the request for the destination identified in the message are provided as described above. If any other destination is impacted in the processing of this action, the modem MUST send a Destination Update Message for each impacted destination. Cheng & Berger Expires August 13, 2017 [Page 6] Internet-Draft DLEP Multi-Hop Extension February 2017 3.2.4. Suppress Forwarding The Suppress Forwarding Action is used by a router to indicate to its peer that multi-hop forwarding is to be suppressed. A router may request that multi-hop forwarding may be suppressed on a device wide or destination specific basis. A modem which receives the Suppress Forwarding Data Item in a Session Update Message MUST suppress multi-hop forwarding on a device wide basis. Impact to destination hop counts are provided to the router by the modem as described above. A modem which receives the Suppress Forwarding Data Item in a Destination Announce Message MUST suppress multi-hop forwarding for only the destination indicated in the message. Results are provided as described above. 4. Security Considerations The extension introduces a new mechanism for flow control between a router and modem using the DLEP protocol. The extension does not inherently introduce any additional threats above those documented in [I-D.ietf-manet-dlep]. The approach taken to Security in that document applies equally when running the extension defined in this document. 5. IANA Considerations This document requests the assignment of 3 values by IANA. All assignments are to registries defined by [I-D.ietf-manet-dlep]. It also requests creation of one new registry. 5.1. Extension Type Value This document requests 1 new assignment to the DLEP Extensions Registry named "Extension Tyoe Values" in the range with the "Specification Required" policy. The requested value is as follows: +------+----------------------+ | Code | Description | +------+----------------------+ | TBA1 | Multi-Hop Forwarding | +------+----------------------+ Table 2: Requested Extension Type Value Cheng & Berger Expires August 13, 2017 [Page 7] Internet-Draft DLEP Multi-Hop Extension February 2017 5.2. Data Item Values This document requests 2 new assignments to the DLEP Data Item Registry named "Data Item Values" in the range with the "Specification Required" policy. The requested values are as follows: +-----------+-------------+ | Type Code | Description | +-----------+-------------+ | TBA2 | Hop Count | | | | | TBA3 | Hop Control | +-----------+-------------+ Table 3: Requested Data Item Values 5.3. Hop Control Actions Registry Upon approval of this document, IANA is requested to create a new DLEP registry, named "Hop Control Actions Values". The following table provides initial registry values and the [RFC5226]. defined policies that should apply to the registry: +-------------+------------------------+ | Value | Action/Policy | +-------------+------------------------+ | 0 | Reset | | | | | 1 | Terminate | | | | | 2 | Direct Connection | | | | | 3 | Suppress Forwarding | | | | | 4-65519 | Specification Required | | | | | 65520-65534 | Private Use | | | | | 65535 | Reserved | +-------------+------------------------+ Table 4: Hop Control Actions Values Cheng & Berger Expires August 13, 2017 [Page 8] Internet-Draft DLEP Multi-Hop Extension February 2017 6. References 6.1. Normative References [I-D.ietf-manet-dlep] Ratliff, S., Jury, S., Satterwhite, D., Taylor, R., and (. (Unknown), "Dynamic Link Exchange Protocol (DLEP)", draft- ietf-manet-dlep-24 (work in progress), July 2016. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, <http://www.rfc-editor.org/info/rfc2119>. 6.2. Informative References [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA Considerations Section in RFCs", BCP 26, RFC 5226, DOI 10.17487/RFC5226, May 2008, <http://www.rfc-editor.org/info/rfc5226>. Authors' Addresses Bow-Nan Cheng Lincoln Laboratory Massachusetts Institute of Technology 244 Wood Street Lexington, MA 02420-9108 Email: bcheng@ll.mit.edu Lou Berger (editor) LabN Consulting, L.L.C. Email: lberger@labn.net Cheng & Berger Expires August 13, 2017 [Page 9]