Checking the SONET Frame Checksum
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:
Examining 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 OS command-line interface (CLI) operational mode, use the following command to check for framing errors:
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.
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:
or
 | 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.
