Technical Documentation

Configure Encapsulation to Cisco-HDLC


To set the encapsulation on a T1 physical interface, follow these steps:

  1. In configuration mode, go to the following hierarchy level:
    [edit]user@host# edit interfaces interface-name
  2. Configure Cisco-HDLC:
    [edit interfaces interface-name]user@host# set encapsulation cisco-hdlc
  3. Verify the configuration:
    user@host# show

    For example:

    [edit interfaces t1-0/1/1:8]user@host# show encapsulation hdlc;
  4. Commit the change:
    user@host# commit

    For example:

    [edit interfaces t1-0/1/1:8]user@host# commit commit complete
  5. Check the interface configuration

    user@host# run show interfaces t1-2/1/0:20
    Physical interface: t1-2/1/0:20, Enabled, Physical link is Up
    Interface index: 210, SNMP ifIndex: 173
    Link-level type: Cisco-HDLC, MTU: 1504, Clocking: Internal, Speed: T1,   Loopback: Local, FCS: 16,
    Mode: C/Bit parity, Framing: ESF
    Device flags   : Present Running
    Interface flags: Point-To-Point SNMP-Traps
    Link flags     : Keepalives
    Keepalive settings: Interval 10 seconds, Up-count 1, Down-count 3
    Keepalive: Input: 39 (00:00:06 ago), Output: 0 (never)
    CoS queues     : 4 supported
    Last flapped   : 2004-05-20 21:46:27 UTC (00:14:28 ago)
    Input rate     : 16 bps (0 pps)
    Output rate    : 160 bps (0 pps)
    DS1   alarms   : None
    DS3   alarms   : None
    DS1   defects  : None
    DS3   defects  : None
    Logical interface t1-2/1/0:20.0 (Index 74) (SNMP ifIndex 213)
    Flags: Point-To-Point SNMP-Traps Encapsulation: Cisco-HDLC
    Protocol inet, MTU: 1500
    Flags: None
    Addresses, Flags: Is-Preferred Is-Primary
    Destination:, Local:


This command sets the interface encapsulation to the Cisco HDLC transport protocol. You must configure the interface with Cisco HDLC to ensure that the logical interface remains up in preparation for the ping test.

Published: 2010-01-29