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Checking the FCS Configuration

Purpose

If you are having problems with a connection, check your router’s FCS configuration and, if possible, the FCS configuration on the router on the other side of the connection.

Action

From the Junos OS CLI operational mode, use one of the following two commands to check the SONET frame checksum:

user@host> show configuration interfaces |interface-name

user@host> show interfacesinterface-name

Note: The option to display a specific configuration with the show configuration command hierarchy was introduced in Junos OS Release 5.3.

Sample Output 1

user@host> show configuration interfaces so-0/0/0

encapsulation cisco-hdlc;
sonet-options {
fcs 32;
    payload-scrambler;
}
unit 0 {
    family inet {
        address 9.0.0.2/32 {
            destination 9.0.0.1;
        }
    }
    family mpls;
}

Sample Output 2

user@host> show interfaces so-0/0/1

Physical interface: so-0/0/1, Enabled, Physical link is Up
  Interface index: 48, SNMP ifIndex: 114
  Link-level type: PPP, MTU: 4474, Clocking: Internal, SONET mode, Speed: OC3, Loopback: None, FCS: 32,
   Payload scrambler: Disabled
  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: 70627 (00:00:07 ago), Output: 70791 (00:00:08 ago)
  LCP state: Opened
  NCP state: inet: Opened, inet6: Not-configured, iso: Opened, mpls: Not-configured
  Input rate     : 78056456 bps (6504 pps)
  Output rate    : 78044840 bps (6503 pps)
  SONET alarms   : None
  SONET defects  : None
  Logical interface so-0/0/1.0 (Index 61) (SNMP ifIndex 118) 
    Flags: Point-To-Point SNMP-Traps Encapsulation: PPP
    Protocol inet, MTU: 4470, Flags: None
      Addresses, Flags: Is-Preferred Is-Primary
        Destination: 192.168.50.0/30, Local: 192.168.50.1
    Protocol iso, MTU: 4470, Flags: None

Meaning

Sample output 1 shows that FCS 32 is configured. If you use the show configuration or show configuration interfaces command, you must scroll to the particular interface for the FCS configuration status.

Meaning

Sample output 2 shows that FCS 32 is configured. To change the FCS configuration, see Returning to the Default 16-Bit Checksum, Configuring a 16-Bit Checksum, or Configuring a 32-Bit Checksum.