MIT Lincoln Laboratory

Massachusetts Institute of Technology 244 Wood Street Lexington MA 02421-6426 USA bcheng@ll.mit.edu

LabN Consulting, L.L.C.

lberger@labn.net

MANET This document defines an extension to the Dynamic Link Exchange Protocol (DLEP) to provide the range of latency that can be experienced on a link.

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. The base DLEP specification includes the Latency Data Item, which provides a single, implementation-dependent latency value on a link. This document adds the ability to relay the minimum and maximum latency range seen on a link. The extension defined in this document is referred to as "Latency Range". This document defines a new DLEP Extension Type Value that is used to indicate the use of the extension; see . A new DLEP Data Item is defined in .

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 when, and only when, they appear in all capitals, as shown here.

Extension Usage and Identification The use of the Latency Range Extension SHOULD be configurable. To indicate that the Latency Range Extension is to be used, an implementation MUST include the Latency Range Extension Type Value in the Extensions Supported Data Item. The Extensions Supported Data Item is sent and processed according to . Note: The usage of the extension defined in this document does not impact processing associated with the Latency Data Item defined in . The Latency Range Extension Type Value is 4; see .

Latency Range Data Item The Latency Range Data Item serves much the same purpose as the Latency Data Item defined in with the addition of being able to communicate the latency range that can be experienced by traffic on a link. The Latency Range Data Item MUST be included in the Session Initialization Response Message, with default values to be used on a session-wide basis. The Latency Range Data Item also MAY be carried in any message where the Latency Data Item is allowed and is carried as an additional data item. When present, the Latency Range Data Item MUST be processed according to the same rules as the Latency Data Item defined in . The format of the Latency Range Data Item is:

Data Item Type:

28

Length:

16

Maximum Latency:

A 64-bit unsigned integer, representing the longest transmission delay, in microseconds, that a packet encounters as it is transmitted over the link.

Minimum Latency:

A 64-bit unsigned integer, representing the shortest transmission delay, in microseconds, that a packet can encounter as it is transmitted over the link.

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
4	Latency Range

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
28	Latency Range

References Normative References Informative References

Acknowledgments Helpful comments were received from members of the MANET working group, including , , and .