Mdl Standards; Fdl Standards; Timeout Of Received Mdl And Fdl Messages; Table 9: Mdl And Fdl Message Strings And Message Types - Juniper JUNOSE SOFTWARE FOR E SERIES 11.3.X - PHYSICAL LAYER CONFIGURATION GUIDE 2010-09-24 Configuration Manual

JunosE 11.3.x Physical Layer Configuration Guide
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modules that support MDL and FDL, see ERX Module Guide, Appendix A, Module Protocol
Support.
You can use MDL and FDL messages to determine the status of a link and to display
statistics for the remote end of a connection. MDL and FDL messages do not interfere
with other data transmitted over the link.

MDL Standards

You can configure channelized T3 interfaces to send MDL messages that comply with
ANSI T1.107a-1990 Standard for Telecommunications—Digital Hierarchy – Supplement
to Formats Specification (August 1990). MDL messages identify a particular link by
sharing common codes for data such as the equipment identifier, line identifier, frame
identifier, and unit.

FDL Standards

Similarly, you can configure T1 channels to send FDL messages that comply with either
or both of the following standards:
ANSI T1.403-1989 Standard for Telecommunications—Network and Customer
Installation Interfaces – DS1 Metallic Interface – Robbed-bit Signaling State Definitions
(1989)
FDL messages that comply with the ANSI standard identify a particular link by sharing
common codes for data such as the equipment identifier, line identifier, frame identifier,
and unit.
AT&T Technical Reference 54016—Requirements for Interfacing Digital Terminal
Equipment to Services Employing the Extended Superframe Format (September 1989)
FDL messages that comply with the AT&T standard identify a particular link by sharing
performance data and do not use common codes for data such as the equipment
identifier, line identifier, frame identifier, and unit.

Timeout of Received MDL and FDL Messages

When a line module receives an MDL or FDL message string, it stores the strings for a
period of 10 seconds after the last message was received. If the line module does not
receive another message of any type containing the same string within 10 seconds, it
erases the local copy of the message.
Most MDL and FDL message strings are common to all three types of messages that can
be transmitted: path identifications, idle signals, and test signals. Certain message strings,
however, are unique to a particular message type. Table 9 on page 106 briefly describes
each MDL/FDL message string and indicates, with a checkmark ( ), the types of messages
in which it can be sent.

Table 9: MDL and FDL Message Strings and Message Types

Message
String Description
eic Equipment identification code
Path Idle Signal
Message Message
Copyright © 2010, Juniper Networks, Inc.
Test Signal
Message