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Routing Manet DLEP PHY TLV This document defines an extension to the Dynamic Link Exchange Protocol (DLEP) to provide the utilization of a radio channel.

Introduction The Dynamic Link Exchange Protocol (DLEP) is defined in . 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. Radio channel utilization provides a packet/frame independent measurement how a radio channel is used and how much resources are still available. While incoming and outgoing traffic can be easily measured on the router, the amount of airtime used by management traffic of the radio is invisible to the router, as is unicast traffic between two adjacent radios (unless the radio supports promiscous mode). This could present the a fully utilized radio channel to the router as totally empty. Getting a direct radio level information how much time on the radio channel has been used up by incoming or outgoing data or control frames allows a router to calculate a better routing metric or allows management agents to detect a channel being unusable for communication because of external jamming.

Requirements Language In many IETF documents, several words, when they are in all capitals as shown below, are used to signify the requirements in the specification. These capitalized words can bring significant clarity and consistency to documents because their meanings are well defined. This document defines how those words are interpreted in IETF documents when the words are in all capitals.

• These words can be used as defined here, but using them is not required. Specifically, normative text does not require the use of these key words. They are used for clarity and consistency when that is what's wanted, but a lot of normative text does not use them and is still normative.
• The words have the meanings specified herein only when they are in all capitals.
• When these words are not capitalized, they have their normal English meanings and are not affected by this document.

Authors who follow these guidelines should incorporate this phrase near the beginning of their 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 when, and only when, they appear in all capitals, as shown here.

Extension Usage and Identification The use of the Channel Utilization Extension SHOULD be configurable. To indicate that the Channel Utilization Extension is to be used, an implementation MUST include the Radio Channel Utilization Extension ID in the Extensions Supported Data Item. The Extensions Supported Data Item is sent and processed according to . The Channel Utilization TLVs can be used by the router to improve the tracking of channel usage by different radios and give a more exact estimate how much free capacity the channel has currently. This information can be used for adjusting timing intervals between automatically generated data, e.g. HELLO messages of the local routing protocol. All four Data Items are 64 bit unsigned integers time measurements in nanoseconds since an arbitrary starting point, e.g. the radio bootup. Each value monotonically increases for the entire duration of the DLEP session; they are never reset. Each of the four data items tracks the time the radio is in a certain type of operation. Channel utilization data types

Type	Description
Active	Time the radio has been operational and able to interact with the channel
Busy	Time the radio channel was blocked for an arbitrary reason
RX	Time the radio was receiving data
TX	Time the radio was transmitting data

A radio that doesn't track the time for receiving (RX) and transmitting (TX) data explicitly MUST add all time intervals the radio channel is not free into the Radio Channel Busy Data Item. The time the radio channel has been free can be calculated by substracting the values of Busy, Rx and Tx from the value provided by the Radio Active Channel Data Item. By tracking these values over time the router can calculate the channel usage statistics for routing metrics or report the received value to a management layer. A radio that is using independent channel resources for each neighbor (e.g. by beam forming) can also track and report channel usage time for each DLEP neighbor.

Data Items All four Data Items of this extension can be used both as Session specific and Destination specific metrics. If the radio is only tracking channel usage on the interface level, the Data Items are used in SessionInitResponse and SessionUpdate messages. If the radio also is tracking channel usage for each Destination, they are also used in DestinationUp, DestinationUpdate and DestinationAnnounceResponse messages. All four Data Items contain a single 64 bit unsigned integer time interval measured in nanoseconds as the TLV value.

Radio Channel Active Data Item Radio Channel Active Item contains information how long the radio channel has been active. This provides the router with a reference to interpret the values provided by the other three Data Items. Because of this the value in this item must be larger than the values in the other three Data Items this extensions defines together. This Data Item is mandatory for SessionInitResponse messages. The format of the Radio Channel Active Data Item is:

Data Item Type:

TBD1

Length:

8

Active Time:

Time in nanoseconds since the channel has been in use.

Radio Channel Busy Data Item Radio Channel Busy Item contains information how much time the radio channel has been busy, not including the time provided in the Channel Rx and Chanel Tx Data Item. The format of the Radio Channel Busy Data Item is:

Data Item Type:

TBD2

Length:

8

Busy Time:

Time in nanoseconds the channel was busy during its active time.

Radio Channel Rx Data Item Radio Channel Rx Item contains information how much time the local radio has been receiving data from other radios. The format of the Radio Channel Rx Data Item is:

Data Item Type:

TBD3

Length:

8

Rx Time:

Time in nanoseconds the local radio has received data from other radios during its active time.

Radio Channel Tx Data Item Radio Channel Tx Item contains information how much time the local radio has been transmitting data to other radios. The format of the Radio Channel Tx Data Item is:

Data Item Type:

TBD4

Length:

8

Tx Time:

Time in nanoseconds the local radio has transmitted data to other radios during its active time.

Security Considerations The extension introduces a new Data Item for DLEP. The extension does not inherently introduce any additional vulnerabilities above those documented in . The approach taken to security in that document applies equally when running the extension defined in this document.

IANA Considerations As described below, IANA has assigned two values per this document. Both assignments are to registries defined by .

Extension Type Value IANA has assigned the following value in the "Extension Type Values" registry within the "Dynamic Link Exchange Protocol (DLEP) Parameters" registry. The new value is in the range with the "Specification Required" policy: New Extension Type Value

Code	Description	Reference
TBD5	Radio Channel Utilization	This document

Data Item Value IANA has assigned the following value in the "Data Item Type Values" registry within the "Dynamic Link Exchange Protocol (DLEP) Parameters" registry. The new value is in the range with the "Specification Required" policy: New Data Item Value

Type Code	Description	Reference
TBD1	Radio Channel Active	This document
TBD2	Radio Channel Busy	This document
TBD3	Radio Channel Rx	This document
TBD4	Radio Channel Tx	This document

Normative References In many standards track documents several words are used to signify the requirements in the specification. These words are often capitalized. This document defines these words as they should be interpreted in IETF documents. This document specifies an Internet Best Current Practices for the Internet Community, and requests discussion and suggestions for improvements. RFC 2119 specifies common key words that may be used in protocol specifications. This document aims to reduce the ambiguity by clarifying that only UPPERCASE usage of the key words have the defined special meanings. When routing devices rely on modems to effect communications over wireless links, they need timely and accurate knowledge of the characteristics of the link (speed, state, etc.) in order to make routing decisions. In mobile or other environments where these characteristics change frequently, manual configurations or the inference of state through routing or transport protocols does not allow the router to make the best decisions. This document introduces a new protocol called the Dynamic Link Exchange Protocol (DLEP), which provides a bidirectional, event-driven communication channel between the router and the modem to facilitate communication of changing link characteristics. Informative References Many protocols make use of points of extensibility that use constants to identify various protocol parameters. To ensure that the values in these fields do not have conflicting uses and to promote interoperability, their allocations are often coordinated by a central record keeper. For IETF protocols, that role is filled by the Internet Assigned Numbers Authority (IANA). To make assignments in a given registry prudently, guidance describing the conditions under which new values should be assigned, as well as when and how modifications to existing values can be made, is needed. This document defines a framework for the documentation of these guidelines by specification authors, in order to assure that the provided guidance for the IANA Considerations is clear and addresses the various issues that are likely in the operation of a registry. This is the third edition of this document; it obsoletes RFC 5226.