Use Loopback Testing for Channelized OC12 Interfaces
- Checklist for Using Loopback Testing for Channelized OC12 and Channelized OC12 IQ Interfaces
- Diagnose a Suspected Hardware Problem with a Channelized OC12 or Channelized OC12 IQ Interface
- Create a Loopback
- Verify That the Interface Is Up
- Clear Interface Statistics
- Force the Link Layer to Stay Up
- Verify the Status of the Logical Interface
- Ping the Channelized Interface
- Check for Interface Error Statistics
- Diagnose a Suspected Circuit Problem
Checklist for Using Loopback Testing for Channelized OC12 and Channelized OC12 IQ Interfaces
Purpose
To use loopback testing to isolate Channelized OC12 and Channelized OC12 IQ interface problems. The naming convention for the Channelized OC12 IQ interface varies depending on the type of interface.
Action
Table 1 provides links and commands for using loopback testing to isolate Channelized OC12 and Channelized OC12 IQ interface problems.
Table 1: Checklist for Using Loopback Testing for Channelized OC12 and Channelized OC12 IQ Interfaces
Tasks | Command or Action |
|---|---|
| Diagnose a Suspected Hardware Problem with a Channelized OC12 or Channelized OC12 IQ Interface | |
Connect the TX port to the RX port. | |
[edit interfaces t3-fpc/pic/port:channel t3 options] | |
show interfaces t3-fpc/pic/port:channel extensive | |
clear interfaces statistics t3-fpc/pic/port:channel | |
[edit interfaces t3-fpc/pic/port:channel] | |
[edit interfaces t3-fpc/pic/port:channel] | |
show interfaces t3-fpc/pic/port:channel | |
ping interface t3-fpc/pic/port:channel local-IP-address bypass-routing count 1000 rapid | |
show interfaces t3-fpc/pic/port:channel extensive | |
| Diagnose a Suspected Circuit Problem | |
[edit interfaces t3-fpc/pic/port:channel t3-options] | |
Perform Steps 2 through 8 from Diagnose a Suspected Hardware Problem with a Channelized OC12 or Channelized OC12 IQ Interface. | |
Diagnose a Suspected Hardware Problem with a Channelized OC12 or Channelized OC12 IQ Interface
Problem
To diagnose a suspected hardware problem with a Channelized OC12 or Channelized OC12 IQ interface, follow these steps:
Solution
- Create a Loopback
- Verify That the Interface Is Up
- Clear Interface Statistics
- Force the Link Layer to Stay Up
- Verify the Status of the Logical Interface
- Ping the Channelized Interface
- Check for Interface Error Statistics
Create a Loopback
Purpose
You can create a physical loopback or configure a local loopback to help diagnose a suspected hardware problem. Creating a physical loopback is recommended because it allows you to test and verify the Channelized OC12 or Channelized OC12 IQ port. If a field engineer is not available to create the physical loopback, you can configure a local loopback for the interface. The local loopback creates a loopback internally in the Physical Interface Card (PIC).
 | Note: For a list of interface types associated with the Channelized OC12 IQ interface, see the Junos OS Network Interfaces Library for Routing Devices. |
Create a Physical Loopback
Action
To create a physical loopback at the port, connect the transmit port to the receive port.
Meaning
When you create and test a physical loopback, you are testing the transmit and receive ports of the PIC. This action is recommended if a field engineer is available to create the physical loop as it provides a more complete test of the PIC.
Configure a Local Loopback
Action
To configure a local loopback, follow these steps:
| Note: For a list of interface types associated with the Channelized OC12 IQ interface, see the Junos Network Interfaces Configuration Guide. |
- In configuration mode, go to the following hierarchy level:[edit]user@host# edit interfaces t3-fpc/pic/port:channel t3-options
- Configure the local loopback:[edit interfaces t3-fpc/pic/port:channel t3-options] user@host# set loopback local
The following is an example of the name for a T3 channel on a channelized DS3 interface:
[edit interfaces t3-2/1/0:2 t3-options] - Verify the configuration:user@host# show
For example:
[edit interfaces t3-2/1/0:2 t3-options]user@host# show loopback local; - Commit the configuration:user@host# commit
For example:
[edit interfaces t3-2/1/1:2 t3-options]user@host# commit commit complete
Meaning
When you create a local loopback, you create an internal loop on the interface being tested. A local loopback loops the traffic internally on that PIC. A local loopback tests the interconnection of the PIC but does not test the transmit and receive ports.
| Note: Remember to delete the loopback statement after completing the test. |
Verify That the Interface Is Up
Purpose
Display the status of a Channelized OC12 or Channelized OC12 IQ interface to determine whether the physical link is up or down.
Action
To verify that the status of the Channelized OC12 or Channelized OC12 IQ interface is up, use the following Junos OS command-line interface (CLI) operational mode command:
| Note: For a list of interface types associated with the Channelized OC12 IQ interface, see Junos Network Interfaces Configuration Guide. |
Sample Output
user@host> show interfaces t3-0/3/0:0 extensive Physical interface: t3-0/3/0:0, Enabled, Physical link is Up
Interface index: 193, SNMP ifIndex: 118, Generation: 122
Link-level type: PPP, MTU: 4474, Clocking: Internal, SONET mode, Speed: T3,
Loopback: Local, SONET Loopback: None, FCS: 16, Mode: C/Bit parity
Device flags : Present Running
Interface flags: Point-To-Point SNMP-Traps
Link flags : Keepalives
Hold-times : Up 0 ms, Down 0 ms
CoS queues : 4 supported
Last flapped : 2004-05-21 15:23:34 UTC (00:05:00 ago)
Statistics last cleared: Never
Traffic statistics:
Input bytes : 0 0 bps
Output bytes : 0 0 bps
Input packets: 0 0 pps
Output packets: 0 0 pps
Input errors:
Errors: 0, Drops: 0, Framing errors: 0, Bucket drops: 0, Policed discards: 0,
L3 incompletes: 0, L2 channel errors: 0, L2 mismatch timeouts: 0,
HS link CRC errors: 0, SRAM errors: 0
Output errors:
Carrier transitions: 1, Errors: 0, Drops: 0, Aged packets: 0
DS3 alarms : None
SONET alarms : None
DS3 defects : None
SONET defects : None
DS3 media: Seconds Count State
AIS 0 0 OK
LOF 0 0 OK
LOS 0 0 OK
IDLE 0 0 OK
YELLOW 0 0 OK
BPV 0 0
EXZ 0 0
LCV 0 0
PCV 0 0
CCV 0 0
LES 0
PES 0
PSES 0
CES 0
CSES 0
SEFS 0
UAS 0
HDLC configuration:
Policing bucket: Disabled
Shaping bucket : Disabled
Giant threshold: 4484, Runt threshold: 3
Idle cycle flag: flags, Start end flag: shared
DSU configuration:
Compatibility mode: None, Scrambling: Disabled, Subrate: Disabled
FEAC loopback: Inactive, Response: Disabled, Count: 0
DS-3 BERT configuration:
BERT time period: 10 seconds, Elapsed: 0 seconds
Algorithm: 2^3 - 1, Pseudorandom (1), Induced error rate: 10e-0
Interface transmit queues:
B/W WRR Packets Bytes
Queue0 0 0
Transmitted: 0 0
Drops: 0 0
Errors: 0
Queue1 0 0
Transmitted: 0 0
Drops: 0 0
Errors: 0
Queue2 0 0
Transmitted: 0 0
Drops: 0 0
Errors: 0
Queue3 0 0
Transmitted: 0 0
Drops: 0 0
Errors: 0
SONET PHY: Seconds Count State
PLL Lock 0 0 OK
PHY Light 0 0 OK
SONET section:
BIP-B1 1 22
SEF 0 0 OK
LOS 0 0 OK
LOF 0 0 OK
ES-S 1
SES-S 0
SEFS-S 0
SONET line:
BIP-B2 1 307
REI-L 0 0
RDI-L 3 1 OK
AIS-L 0 0 OK
BERR-SF 0 0 OK
BERR-SD 0 0 OK
ES-L 1
SES-L 0
UAS-L 0
ES-LFE 3
SES-LFE 3
UAS-LFE 0
SONET path:
BIP-B3 1 35
REI-P 1 7
LOP-P 0 0 OK
AIS-P 0 0 OK
RDI-P 0 0 OK
UNEQ-P 0 0 OK
PLM-P 1 1 OK
ES-P 1
SES-P 0
UAS-P 0
ES-PFE 1
SES-PFE 0
UAS-PFE 0
Received SONET overhead:
F1 : 0x00, J0 : 0x00, K1 : 0x00, K2 : 0x00
S1 : 0x00, C2 : 0x04, C2(cmp) : 0x04, F2 : 0x00
Z3 : 0x00, Z4 : 0x00, S1(cmp) : 0x00
Transmitted SONET overhead:
F1 : 0x00, J0 : 0x01, K1 : 0x00, K2 : 0x00
S1 : 0x00, C2 : 0x04, F2 : 0x00, Z3 : 0x00
Z4 : 0x00
Received path trace: t3-0/1/0:0
74 33 2d 30 2f 31 2f 30 3a 30 00 00 00 00 0d 0a t3-0/1/0:0......
Transmitted path trace: t3-0/3/0:0
74 33 2d 30 2f 33 2f 30 3a 30 00 00 00 00 00 00 t3-0/3/0:0......
Packet Forwarding Engine configuration:
Destination slot: 0, PLP byte: 1 (0x00)
CoS transmit queue Bandwidth Buffer Priority Limit
% bps % bytes
0 best-effort 95 42499200 95 0 low none
3 network-control 5 2236800 5 0 low none
Meaning
The sample output shows that the physical link is up and there are no OC12 alarms or defects. You should not see any OC12 alarms.
Clear Interface Statistics
Purpose
You must reset the Channelized OC12 or Channelized OC12 IQ interface statistics before initiating the ping test. Resetting the statistics provides a clean start so that previous input or output errors and packet statistics do not interfere with the current efforts to diagnose the problem.
Action
To clear all statistics for the interface, use the following Junos OS CLI operational mode command:
Sample Output
user@host> clear interfaces statistics t3-1/1/0:0 user@host>
Meaning
This command clears the interface statistics counters for the Channelized OC12 interface only.
| Note: After a Graceful Routing Engine switchover (GRES) you must run clear interface statistics again or interface statistics will display junk vales. |
Force the Link Layer to Stay Up
Purpose
To complete the loopback test, the link layer must remain up. However, Junos OS is designed to recognize that loop connections are not valid connections and to bring the link layer down. You need to force the link layer to stay up by making some configuration changes to the encapsulation and keepalives.
Force the link layer to stay up, follow these steps:
Configure Encapsulation to Cisco-HDLC
Action
To set the encapsulation on a T3 physical interface, follow these steps:
- In configuration mode, go to the following hierarchy level:[edit]user@host# edit interfaces t3-fpc/pic/port:channel
- Configure Cisco-HDLC:[edit interfaces t3-fpc/pic /port:channel ]user@host# set encapsulation cisco-hdlc
- Verify the configuration:user@host# show
For example:
[edit interfaces t3-0/1/1:8]user@host# show encapsulation hdlc; - Commit the change:user@host# commit
For example:
[edit interfaces t3-0/1/1:8]user@host# commit commit complete
Meaning
This command sets the interface encapsulation to the Cisco High-level Data-Link Control (HDLC) transport protocol.
Configure No-Keepalives
Action
To disable the sending of link-layer keepalives on a Channelized OC12 or Channelized OC12 IQ interface, follow these steps:
| Note: For a list of interface types associated with the Channelized OC12 IQ interface, see Junos Network Interfaces Configuration Guide. |
- In configuration mode, go to the following hierarchy level:[edit]user@host# edit interfaces t3-fpc/pic/port:channel
- Configure no-keepalives:[edit interfaces t3-fpc/pic/port:channel]user@host# set no-keepalives
- Verify the configuration:user@host# show
For example:
[edit interfaces t3-0/1/1:8]user@host# show no-keepalives; - Commit the change:user@host# commit
For example:
[edit interfaces t3-0/1/1:8]user@host# commit commit complete
Meaning
By setting no-keepalives, the link layer is forced to stay up. If the setting remains at keepalive, the router will recognize that the same link-layer keepalives are being looped back and will bring the link layer down.
Verify the Status of the Logical Interface
Purpose
To verify the status of the logical interface, use the following Junos OS CLI operational mode command:
Action
| Note: For a list of interface types associated with the Channelized OC12 IQ interface, see Junos Network Interfaces Configuration Guide. |
Sample Output
user@host> show interfaces t3-0/3/0:11 Physical interface: t3-0/3/0:11, Enabled, Physical link is Up
Interface index: 204, SNMP ifIndex: 129
Link-level type: Cisco-HDLC, MTU: 4474, SONET mode, Speed: T3, Loopback: Local,
SONET Loopback: None, FCS: 16, Mode: C/Bit parity
Device flags : Present Running
Interface flags: Point-To-Point SNMP-Traps
Link flags : No-Keepalives
CoS queues : 4 supported
Last flapped : 2004-05-21 15:23:34 UTC (01:34:24 ago)
Input rate : 0 bps (0 pps)
Output rate : 0 bps (0 pps)
DS3 alarms : None
SONET alarms : None
DS3 defects : None
SONET defects : None
DS-3 BERT configuration:
BERT time period: 0 seconds, Elapsed: 0 seconds
Algorithm: Unknown (0), Induced error rate: 10e-0
Logical interface t3-0/3/0:11.0 (Index 71) (SNMP ifIndex 130)
Flags: Point-To-Point SNMP-Traps Encapsulation: Cisco-HDLC
Protocol inet, MTU: 4470
Flags: None
Addresses, Flags: Is-Preferred Is-Primary
Destination: 10.0.0.0/30, Local: 10.0.0.1, Broadcast: 10.0.0.3
Meaning
The sample output shows that the channelized interface has the physical and logical links up. There are no alarms or defects.
Ping the Channelized Interface
Purpose
Use the ping command to verify the loopback connection.
Action
To ping the local interface, use the following Junos OS CLI operational mode command:
| Note: For a list of interface types associated with the Channelized OC12 IQ interface, see the Junos Network Interfaces Configuration Guide. |
Sample Output
user@host> ping interface t3-0/3/0:11 10.0.0.1
bypass-routing count 1000 rapid PING 10.0.0.1 (10.0.0.1): 56 data bytes !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! --- 10.0.0.1 ping statistics --- 1000 packets transmitted, 1000 packets received, 0% packet loss round-trip min/avg/max/stddev = 0.439/0.694/42.590/2.206 ms
Meaning
This command sends 1000 ping packets out of the channelized interface to the local IP address. The ping should complete successfully with no packet loss. If there is any persistent packet loss, open a case with the Juniper Networks Technical Assistance Center (JTAC) at support@juniper.net, or at 1-888-314-JTAC (within the United States) or 1-408-745-9500 (from outside the United States).
Check for Interface Error Statistics
Purpose
Persistent interface error statistics indicate that you need to open a case with JTAC.
Action
To check the local interface for error statistics, use the following Junos OS CLI operational mode command:
| Note: For a list of interface types associated with the Channelized OC12 IQ interface, see the Junos Network Interfaces Configuration Guide. |
Sample Output
user@host> show interfaces t3-0/3/0:11 extensive Physical interface: t3-0/3/0:11, Enabled, Physical link is Up
Interface index: 204, SNMP ifIndex: 129, Generation: 133
Link-level type: Cisco-HDLC, MTU: 4474, SONET mode, Speed: T3, Loopback: Local,
SONET Loopback: None, FCS: 16, Mode: C/Bit parity
Device flags : Present Running
Interface flags: Point-To-Point SNMP-Traps
Link flags : No-Keepalives
Hold-times : Up 0 ms, Down 0 ms
CoS queues : 4 supported
Last flapped : 2004-05-21 15:23:34 UTC (01:36:27 ago)
Statistics last cleared: Never
Traffic statistics:
Input bytes : 109318 0 bps
Output bytes : 109318 0 bps
Input packets: 1669 0 pps
Output packets: 1669 0 pps
Input errors:
Errors: 0, Drops: 0, Framing errors: 0, Bucket drops: 0, Policed discards: 0,
L3 incompletes: 0, L2 channel errors: 0, L2 mismatch timeouts: 0,
HS link CRC errors: 0, SRAM errors: 0
Output errors:
Carrier transitions: 3, Errors: 0, Drops: 0, Aged packets: 0
DS3 alarms : None
SONET alarms : None
DS3 defects : None
SONET defects : None
DS3 media: Seconds Count State
AIS 0 0 OK
LOF 0 0 OK
LOS 0 0 OK
IDLE 0 0 OK
YELLOW 0 0 OK
BPV 0 0
EXZ 0 0
LCV 0 0
PCV 0 0
CCV 0 0
LES 0
PES 0
PSES 0
CES 0
CSES 0
SEFS 0
UAS 0
HDLC configuration:
Policing bucket: Disabled
Shaping bucket : Disabled
Giant threshold: 4484, Runt threshold: 3
Idle cycle flag: flags, Start end flag: shared
DSU configuration:
Compatibility mode: None, Scrambling: Disabled, Subrate: Disabled
FEAC loopback: Inactive, Response: Disabled, Count: 0
DS-3 BERT configuration:
BERT time period: 0 seconds, Elapsed: 0 seconds
Algorithm: Unknown (0), Induced error rate: 10e-0
Interface transmit queues:
B/W WRR Packets Bytes
Queue0 0 0
Transmitted: 0 0
Drops: 0 0
Errors: 0
Queue1 0 0
Transmitted: 0 0
Drops: 0 0
Errors: 0
Queue2 0 0
Transmitted: 0 0
Drops: 0 0
Errors: 0
Queue3 0 0
Transmitted: 1669 109318
Drops: 0 0
Errors: 0
SONET PHY: Seconds Count State
PLL Lock 0 0 OK
PHY Light 0 0 OK
SONET section:
BIP-B1 1 22
SEF 0 0 OK
LOS 0 0 OK
LOF 0 0 OK
ES-S 1
SES-S 0
SEFS-S 0
SONET line:
BIP-B2 1 307
REI-L 0 0
RDI-L 3 1 OK
AIS-L 0 0 OK
BERR-SF 0 0 OK
BERR-SD 0 0 OK
ES-L 1
SES-L 0
UAS-L 0
ES-LFE 3
SES-LFE 3
UAS-LFE 0
SONET path:
BIP-B3 1 37
REI-P 1 23
LOP-P 0 0 OK
AIS-P 0 0 OK
RDI-P 0 0 OK
UNEQ-P 0 0 OK
PLM-P 1 1 OK
ES-P 1
SES-P 0
UAS-P 0
ES-PFE 1
SES-PFE 0
UAS-PFE 0
Received SONET overhead:
F1 : 0x00, J0 : 0x00, K1 : 0x00, K2 : 0x00
S1 : 0x00, C2 : 0x04, C2(cmp) : 0x04, F2 : 0x00
Z3 : 0x00, Z4 : 0x00, S1(cmp) : 0x00
Transmitted SONET overhead:
F1 : 0x00, J0 : 0x01, K1 : 0x00, K2 : 0x00
S1 : 0x00, C2 : 0x04, F2 : 0x00, Z3 : 0x00
Z4 : 0x00
Received path trace: t3-0/1/0:11
74 33 2d 30 2f 31 2f 30 3a 31 31 00 00 00 0d 0a t3-0/1/0:11.....
Transmitted path trace: t3-0/3/0:11
74 33 2d 30 2f 33 2f 30 3a 31 31 00 00 00 00 00 t3-0/3/0:11.....
Packet Forwarding Engine configuration:
Destination slot: 0, PLP byte: 1 (0x02)
CoS transmit queue Bandwidth Buffer Priority Limit
% bps % bytes
0 best-effort 95 42499200 95 0 low none
3 network-control 5 2236800 5 0 low none
Logical interface t3-0/3/0:11.0 (Index 71) (SNMP ifIndex 130) (Generation 22)
Flags: Point-To-Point SNMP-Traps Encapsulation: Cisco-HDLC
Protocol inet, MTU: 4470, Generation: 31, Route table: 0
Flags: None
Addresses, Flags: Is-Preferred Is-Primary
Destination: 10.0.0.0/30, Local: 10.0.0.1, Broadcast: 10.0.0.3, Generation: 43
Meaning
Check for any error statistics that may appear in the output. There should not be any input or output errors. If there are any persistent input or output errors, open a case with JTAC at support@juniper.net, or at 1-888-314-JTAC (within the United States) or 1-408-745-9500 (from outside the United States).
Diagnose a Suspected Circuit Problem
Purpose
When you suspect a circuit problem, it is important to work with the transport-layer engineer to resolve the problem. The transport-layer engineer may ask you to create a loop from the router to the network, or the engineer may create a loop to the router from various points in the network.
To diagnose a suspected circuit problem, follow these steps:
- Loop the Entire T3 Interface Toward the Network
- Create a Loop to the Router from Various Points in the Network
Loop the Entire T3 Interface Toward the Network
Purpose
Creating a loop from the entire T3 interface to the network allows the transport-layer engineer to test the router from various points in the network and isolate the problem..
| Note: For a list of interface types associated with the Channelized OC12 IQ interface, see the Junos Network Interfaces Configuration Guide. |
Action
To create a loop from the entire T3 interface to the network, follow these steps:
- In configuration mode, go to the following hierarchy level:[edit]user@host# edit interfaces t3-fpc/pic/port:channel t3-options
- Configure the loopback:[edit interfaces t3-fpc/pic/port:channel t3-options]user@host# set loopback remote
- Verify the configuration:user@host# show
For example:
[edit interfaces t3-2/1/1:0 t3-options]user@host# show loopback remote; - Commit the configuration:user@host# commit
Meaning
The loopback remote command loops any traffic from the network back into the network.
Create a Loop to the Router from Various Points in the Network
Purpose
The transport-layer engineer creates a loop to the router from various points in the network. You can then perform tests to verify the connection from the router to that loopback in the network.
Action
After the transport-layer engineer has created the loop to the router from the network, you must verify the connection from the router to the loopback in the network. Follow Steps 2 through 7 in Diagnose a Suspected Hardware Problem with a Channelized OC12 or Channelized OC12 IQ Interface. Keep in mind that any problems encountered in the test indicate a problem with the connection from the router to the loopback in the network.
By performing tests to loopbacks at various points in the network, you can isolate the source of the problem.
