Step 3: Verify That the SONET Interface Is Up

Purpose

Displaying the status of the SONET interface provides the information you need to determine whether the physical link is up or down.

Action

To verify that the SONET interface is up, use the following JUNOS command-line interface (CLI) operational mode command:

user@host> show interfaces so-fpc/pic/port

Sample Output 1

The following output is for a SONET interface with the physical link up:

user@host# show interfaces so-2/2/0 

Physical interface: so-2/2/0, Enabled, Physical link is Up

Interface index: 21, SNMP ifIndex: 45

Link-level type: PPP, MTU: 4474, Clocking: Internal, SONET mode, Speed: OC3, 
Loopback: None, FCS: 16,

Payload scrambler: Enabled

Device flags   : Present Running Loop-Detected

Interface flags: Point-To-Point SNMP-Traps

Link flags     : Keepalives

Keepalive settings: Interval 10 seconds, Up-count 1, Down-count 3

Keepalive: Input: 0 (never), Output: 0 (never)

LCP state: Conf-req-sent

NCP state: inet: Down, inet6: Not-configured, iso: Not-configured, mpls: 
Not-configured

Input rate     : 48 bps (0 pps)

Output rate    : 56 bps (0 pps)

SONET alarms   : None

SONET defects  : None

Logical interface so-2/2/0.0 (Index 7) (SNMP ifIndex 33)

Flags: Hardware-Down Point-To-Point SNMP-Traps Encapsulation: PPP

Protocol inet, MTU: 4470, Flags: Protocol-Down

Addresses, Flags: Dest-route-down Is-Preferred Is-Primary

Destination: 10.0.2/24, Local: 10.0.2.1

What It Means

Sample output 1 shows that the physical link is up, the loop is detected, and there are no SONET alarms or defects.

If the physical link is up, continue with Check That the Received and Transmitted Path Trace Are the Same.

Sample Output 2

When you see that the physical link is down, there might be a problem with the port. Sample output 2 shows that the physical link is down:

user@host# show interfaces so-2/2/0

Physical interface: so-2/2/0, Enabled, Physical link is Down

Interface index: 21, SNMP ifIndex: 45

Link-level type: PPP, MTU: 4474, Clocking: Internal, SONET mode, Speed: OC3, 
Loopback: None, FCS: 16,

Payload scrambler: Enabled

Device flags   : Present Running Down

Interface flags: Hardware-Down Point-To-Point SNMP-Traps

Link flags     : Keepalives

Keepalive settings: Interval 10 seconds, Up-count 1, Down-count 3

Keepalive: Input: 0 (never), Output: 0 (never)

LCP state: Conf-req-sent

NCP state: inet: Down, inet6: Not-configured, iso: Not-configured, mpls: 
Not-configured

Input rate     : 0 bps (0 pps)

Output rate    : 0 bps (0 pps)

SONET alarms   : LOL, LOS

SONET defects  : LOL, LOF, LOS, SEF, AIS-L, AIS-P

Logical interface so-2/2/0.0 (Index 7) (SNMP ifIndex 33)

Flags: Hardware-Down Device-Down Point-To-Point SNMP-Traps Encapsulation: PPP

Protocol inet, MTU: 4470, Flags: Protocol-Down

Addresses, Flags: Dest-route-down Is-Preferred Is-Primary

Destination: 10.0.2/24, Local: 10.0.2.1

What It Means

The sample output shows that the physical link is down, the device flags and interface flags are down, and there are SONET alarms and defects.

Table 30 lists problem situations and actions for a physical link that is down.

Table 30: Problems and Solutions for a Physical Link That Is Down

Problem	Action
Cable mismatch	Verify that the fiber connection is correct.
Damaged and/or dirty cable	Verify that the fiber can successfully loop a known good port of the same type.
Too much or too little optical attenuation	Verify that the attenuation is correct per the PIC optical specifications.
The transmit port is not transmitting within the dBm optical range per the specifications	Verify that the Tx power of the optics is within range of the PIC optical specification.