Dynamic Link Exchange Protocol (DLEP) Latency Range
Extension
MIT Lincoln Laboratory
Massachusetts Institute of Technology
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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 .