DLEP Radio Band Extension

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 consist 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 to provide information about the frequency bands used by the radio. This extension does not consider radios which use frequency hopping. Frequency hopping is a much more complicated topic that should be considered in a documents of its own.

Requirements Language 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 Radio Band Extension SHOULD be configurable. To indicate that the Radio Band Extension is to be used, an implementation MUST include the Radio Band Extension Type Value in the Extensions Supported Data Item. The Extensions Supported Data Item is sent and processed according to .

Radio Band Data Item Radio Band Data Item contains information about which radio frequency resources are being used. The Data item MUST be used in the Session Initialization Response message and MAY be used in Session Update messages. The Radio Band Data Item can be used multiple times in the same message to represent multiple radio bands. If the radio/modem wants to provide the destination specific radio bands, the Radio Band Data Item MAY be used in Destination Up, Destination Update and Destination Announce Response messages. Frequency selection is often controlled by the radio configuration. By giving the radio a standardized way to transmit its selected frequency configuration the router can aggregate multiple radios settings into a common information page, can do some basic checking for configuration mistakes by comparing known radio group configuration with their frequency by radio (if the routers have a second communication channel) or forward the data to an upper layer for visualization. The information in this Item gives the router an easy way to calculate the spectral efficiency of a radio link, how much bandwidth is used for the current data-rate reported by DLEP. This can be integrated into the routing metric to focus traffic on links that use the spectrum efficiently. The Item can also be used as an interface to a cognitive radio controller on the router, analyzing the correlation of transmission disruptions with the frequency bands and could be used to change the frequency of the radio in a standardized way. In this case the Radio Band Data Item MAY be used in the Link Characteristics Request and Link Characteristics Response message. Both values in the TLV (Carrier Frequency and Bandwidth) are 64 bit unsigned integers. The format of the Radio Band Data Item is:

Radio Band Data Item Format

Data Item Type:: TBD1
Length:: 17
Center Frequency:: The center frequency of the band in Hz.
Bandwidth:: The bandwidth of the band in Hz.
Flags:: Flags field as defined below.

The Flags field is defined as:

Radio Band Data Item Flags

U:: Uplink Flag, indicating the band is used for transmitting data.
D:: Downlink Flag, indicating the band is used for receiving data.
Reserved:: MUST be written as zero. Ignored on receipt and left for future assignment.

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 .

Data Item Type Values IANA has assigned the following value in the "Data Item Type Values" registry defined by , chapter 15.4. The new value is in the range with the "Specification Required" policy: Data Item Type Values

Type Code	Description
TBD1	Radio Band

Extension Type Values IANA has assigned the following value in the "Extension Type Values" registry defined by , chapter 15.6. The new value is in the range with the "Specification Required" policy: DLEP Extension Types

Code	Description
TBD2	Radio Band