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Check the SONET Frame Checksum

Purpose

If you are having problems with a connection, check that the FCS matches on both sides of the connection.

To check the SONET frame checksum, follow these steps:

  1. Examine Output for Framing Errors
  2. Check the FCS Configuration


Examine Output for Framing Errors

Purpose

By examining the output for an interface, you can determine if framing errors are incrementing in the absence of any SONET alarms or defects.

Action

From the JUNOS command-line interface (CLI) operational mode, use the following command to check for framing errors:

user@host> show interfaces interface-name extensive

Sample Output


user@router1> show interfaces so-1/0/0 extensive
Physical interface: so-1/0/0, Enabled, Physical link is Up
  Interface index: 13, SNMP ifIndex: 18, Generation: 12
  Link-level type: PPP, MTU: 4474, Clocking: Internal, SONET mode, Speed: OC3, Loopback: None, FCS: 16 , Payload scrambler: Enabled
  Device flags   : Present Running
  Interface flags: Link-Layer-Down Point-To-Point SNMP-Traps
  Link flags     : Keepalives
  Hold-times     : Up 0 ms, Down 0 ms
  Keepalive settings: Interval 10 seconds, Up-count 1, Down-count 3
  Keepalive statistics:
    Input : 6 (last seen 00:00:52 ago)
    Output: 11 (last sent 00:00:05 ago)
  LCP state: Opened
  NCP state: inet: Opened, inet6: Not-configured, iso: Opened, mpls: Conf-req-sent
  CHAP state: Not-configured
  Last flapped   : 2002-11-01 22:28:30 UTC (1w5d 23:26 ago)
  Statistics last cleared: 2002-11-14 21:52:51 UTC (00:01:50 ago)
  Traffic statistics:
   Input  bytes  :                  692                    0 bps
   Output bytes  :                  716                   32 bps
   Input  packets:                   23                    0 pps
   Output packets:                   72                    0 pps
  Input errors:
    Errors: 0, Drops: 0, Framing errors: 27 , Runts: 0, Giants: 0, Bucket drops: 0, Policed discards: 0, L3 incompletes: 0,
    L2 channel errors: 0, L2 mismatch timeouts: 0, HS link CRC errors: 0, HS link FIFO overflows: 0
  Output errors:
    Carrier transitions: 0, Errors: 0, Drops: 0, Aged packets: 0, HS link FIFO underflows: 0
  SONET alarms   : None
  SONET defects  : None
  SONET PHY:            Seconds        Count  State
    PLL Lock                  0            0  OK
    PHY Light                 0            0  OK
  SONET section:
    BIP-B1                    0            0
    SEF                       0            0  OK
    LOS                       0            0  OK
    LOF                       0            0  OK
    ES-S                      0
    SES-S                     0
    SEFS-S                    0
  SONET line:
    BIP-B2                    0            0
    REI-L                     0            0
    RDI-L                     0            0  OK
    AIS-L                     0            0  OK
    BERR-SF                   0            0  OK
    BERR-SD                   0            0  OK
    ES-L                      0
    SES-L                     0
    UAS-L                     0
    ES-LFE                    0
    SES-LFE                   0
    UAS-LFE                   0
  SONET path:
    BIP-B3                    0            0
    REI-P                     0            0
    LOP-P                     0            0  OK
    AIS-P                     0            0  OK
    RDI-P                     0            0  OK
    UNEQ-P                    0            0  OK
    PLM-P                     0            0  OK
    ES-P                      0
    SES-P                     0
    UAS-P                     0
    ES-PFE                    0
    SES-PFE                   0
    UAS-PFE                   0
  Received SONET overhead:
    F1      : 0x00, J0      : 0x00, K1      : 0x00, K2      : 0x00
    S1      : 0x00, C2      : 0xcf, C2(cmp) : 0xcf, F2      : 0x00
    Z3      : 0x00, Z4      : 0x00, S1(cmp) : 0x00, V5      : 0x00
    V5(cmp) : 0x00
  Transmitted SONET overhead:
    F1      : 0x00, J0      : 0x01, K1      : 0x00, K2      : 0x00
    S1      : 0x00, C2      : 0xcf, F2      : 0x00, Z3      : 0x00
    Z4      : 0x00, V5      : 0x00
  Received path trace: router2 so-1/3/1
    73 6c 69 70 70 65 72 79 20 73 6f 2d 31 2f 33 2f   router2 so-1/3/1
    31 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00   ................
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00   ................
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 0d 0a   ................
  Transmitted path trace: router1 so-1/0/0
    68 61 69 72 79 20 73 6f 2d 31 2f 30 2f 30 00 00   router1 so-1/0/0
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00   ................
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00   ................
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00   ................
  HDLC configuration:
    Policing bucket: Disabled
    Shaping bucket : Disabled
    Giant threshold: 4484, Runt threshold: 3
  Packet Forwarding Engine configuration:
    Destination slot: 1, PLP byte: 1 (0x00)
    CoS transmit queue             Bandwidth           Buffer Priority   Limit
                              %          bps   %        bytes
    0 best-effort            95    147744000  95            0      low    none
    3 network-control         5      7776000   5            0      low    none
  Logical interface so-1/0/0.0 (Index 8) (SNMP ifIndex 108) (Generation 9)
    Flags: Device-Down Point-To-Point SNMP-Traps Encapsulation: PPP
    Protocol inet, MTU: 4470, Generation: 15, Route table: 1
      Flags: Is-Primary
      Addresses, Flags: Dest-route-down Is-Default Is-Preferred Is-Primary
        Destination: 1.1.6.1, Local: 1.1.6.2, Broadcast: Unspecified, Generation: 15
    Protocol iso, MTU: 4470, Generation: 16, Route table: 1
      Flags: Is-Primary
    Protocol mpls, MTU: 4458, Generation: 17, Route table: 1
      Flags: Protocol-Down, Is-Primary

Meaning

The sample output shows that Router 1 is configured for FCS 16, that framing errors have incremented to 27, and that there are no SONET alarms or defects. Incrementing framing errors, in the absence of any SONET alarms or defects, are a symptom of SONET frame checksum errors.


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

user@host> show configuration interfaces |interface-name

or

user@host> show interfacesinterface-name

Note: The option to display a specific configuration with the show configuration command hierarchy was introduced in JUNOS 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 Return to the Default 16-Bit Checksum, Configure a 16-Bit Checksum, or Configure a 32-Bit Checksum.


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