Juniper JUNOSE 11.2.X MULTICAST ROUTING, Configuration Manual

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MDL Standards
You can configure 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.
Timeout of Received MDL Messages
When a line module receives an MDL 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 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 5 on page 46 briefly describes
each MDL message string and indicates, with a checkmark (
✓ ), the types of messages
in which it can be sent.
Table 5: MDL Message Strings and Message Types
Test Signal
Message Idle Signal
Message Path
Message
Description
Message
String
✓ ✓ ✓
Equipment identification code eic
✓ ✓ ✓ Frame identification code fic
✓ – – Generator number generator
✓ ✓ ✓ Line identification code lic
– – ✓ Facility identification code pfi
–
✓
– Equipment port number port
✓ ✓ ✓ Unit identification code unit
As long as another message of any type containing the same string is received within 10
seconds, the line module retains the local copy of the message string and resets the
10-second timer for that string.
For example, if a line module receives an MDL test signal message containing an eic
string, and then receives a idle signal message within 10 seconds that also contains an
eic string, it retains the local copy of the most recent eic string received and resets the
10-second timer for that message. However, if 10 seconds pass without the line module
receiving a path identification, test signal, or idle signal message containing an eic string,
the line module erases the local copy of the eic message string.
Copyright © 2010, Juniper Networks, Inc. 46
JunosE 11.2.x Physical Layer Configuration Guide