Configuring 4-Port C37.94 Interface Module

The IEEE C37.94 standard defines the communication of protection relays with communication equipment inside a substation using optical fibers.

The IEEE defines the C37.94 standard as N * 64 kbps optical fiber interface to provide transparent communications between tele-protection relays and multiplexers equipments. The C37.94 standard describes the interconnection details for the variable N, (where N = 1, 2…12), which describes a multiple of 64 kilobit per second connections at which the communication link is to operate.

The C37.94 interface module supports four ports from port number 0 to 3.

The 4-Port C37.94 interface module is supported on the RSP2 module of the Cisco ASR 902 and ASR 903 routers.

Information About C37.94 Interface Module

This following section provides information about configuring C37.94 interface module on the Cisco ASR 903 Series Router.

Smart Grid Tele-Protection Support

The C37.94 interface module supports smart grid tele-protection.

Smart Grid refers to the electricity delivery system from the point of generation to the point of consumption using analog or digital information and the communication technology for gathering and acting on the information.

Tele-protection refers to the mechanism to quickly switch on alternative routes using tele-protection equipment when a malfunction occurs. The switchover is to improve the performance of the electric grid.

Figure 1. Smart Grid Tele-protection

Overview of C37.94 Frame

The IEEE standard defines a data frame format for C37.94 interface module. The frame format is designed to allow the passage of information in packet format from the multiplexer to the tele-protection equipment and from the tele-protection equipment to the multiplexer equipment.

Features of 4-Port C37.94 Interface Module

The features of 4-Port C37.94 Interface Module are:

  • Supports 4 independent C37.94 interfaces

  • Provides low latency connection over pseudowires

  • Supports allocation of timeslot. Timeslot ranges from 1 to 12

  • Supports Online Insertion and Removal (OIR)

  • Supports traffic switch from active to standby

  • Provides quick switchover to alternative route at the time of a route failure

  • Populates the C37.94 controller indexes in IfTable; the IfTable is defined in IF-MIB

Prerequisites

  • Provider Edges (PEs) must be reachable over MPLS network

  • Sync-E must be configured between pseudowire peers

Restrictions

  • The channelization of N * 64 kbps channels of C37.94 interface is not supported

  • The bandwidth of N * 64 kbps (N ranges from 1 to 12) is supported

  • Pseudowire configuration between local and remote PE with different time slots is not supported

  • Pseudowire configuration is supported only when C37.94 interface is configured on both PE nodes

  • C37.94 controller index in IfTable does not provide the following information:

    • Maximum Transmit Unit (MTU)

    • Counters

Benefits

  • Provides low latency connection to C37.94 interfaces

  • Supports multiple interface modules on single chassis

  • Tele-protection relay checks a failure and thus provides reliable, robust and safe electric grid

  • Provides quick switchover to an alternative route of any route failure

  • Prevents damage to the network and power outages

How to Configure C37.94 Interface Module

Configuring CEM Class

Before you configure CEM class, configure payload size and dejitter buffer values on CEM. 

enable
configure terminal
class cem mycemclass
payload-size 64
dejitter-buffer 20
idle-pattern 0x55
end

Note

  • The default payload size varies with the number of time slots selected.

Configuring CEM

Before you configure CEM group cross-connect, configure the C37.94 controller. 

enable
configure terminal
controller c3794 0/0/0
cem-group 0 timeslots 12
exit
interface cem 0/0/0
no ip address
cem 0
cem class mycemclass
xconnect 10.10.10.10 200 encapsulation mpls 
exit

Note

The controller is auto-configured when the interface module is inserted.

Verifying C37.94 Interface Module Configurations

You use the following show commands to verify the configuration of 4-Port C37.94 interface module:

  • Use the show running-config command to view the configurations. 

    Router# show running-config | sec 0/0/0

controller C3794 0/0/0
  cem-group 0 timeslots 12
interface CEM0/0/0
no ip address
cem 0
  xconnect 10.10.10.10 200 encapsulation mpls

  • Use the show xconnect command to verify the configuration of cross connect between the controllers. 

    Router# show xconnect all

Legend:    XC ST=Xconnect State  S1=Segment1 State  S2=Segment2 State
  UP=Up       DN=Down            AD=Admin Down      IA=Inactive
  SB=Standby  HS=Hot Standby     RV=Recovering      NH=No Hardware

XC ST  Segment 1                         S1 Segment 2                         S2
------+---------------------------------+--+---------------------------------+--
UP pri   ac CE0/0/0:0(CESoPSN Basic)     UP mpls 10.10.10.10 200              UP

  • Use the show cem circuit command to verify the CEM configurations. 

    Router# show cem circuit detail

CEM0/0/0, ID: 0, Line: UP, Admin: UP, Ckt: ACTIVE
Controller state: up, T1/E1 state: up
Idle Pattern: 0xFF, Idle CAS: 0x8
Dejitter: 5 (In use: 0)
Payload Size: 96
Framing: Framed (DS0 channels: 1-12)
CEM Defects Set
None

Signalling: No CAS
RTP: No RTP

Ingress Pkts:    26669            Dropped:             0                   
Egress Pkts:     26669            Dropped:             0                   

CEM Counter Details
Input Errors:    0                    Output Errors:       0                   
Pkts Missing:    0                    Pkts Reordered:      0                   
Misorder Drops:  0                    JitterBuf Underrun:  0                   
Error Sec:       0                    Severly Errored Sec: 0                   
Unavailable Sec: 0                    Failure Counts:      0                  
Pkts Malformed:  0                    JitterBuf Overrun:   0

  • Use the show controllers command to verify the controller configurations. 

    Router# show controllers c3794 0/0/0

C3794 0/0/0 - (A900-IMA4C3794) is up
Configured Channels: 1
Peer Channels      : 1
Alarm                              : Nil
Sending Y-Alarm to Peer Device     : No
Receiving Y-Alarm from Peer Device : No
Transceiver Rx Optical Power :-15 db

Associated Commands

Commands

URL

cem-group

http:/​/​www.cisco.com/​c/​en/​us/​td/​docs/​ios-xml/​ios/​interface/​command/​ir-cr-book/​ir-c1.html#wp2440628600

xconnect

http:/​/​www.cisco.com/​c/​en/​us/​td/​docs/​ios-xml/​ios/​interface/​command/​ir-cr-book/​ir-t2.html#wp8578094790

loopback

http:/​/​www.cisco.com/​c/​en/​us/​td/​docs/​ios-xml/​ios/​interface/​command/​ir-cr-book/​ir-l1.html#wp1033903426

Troubleshooting

You use the following to troubleshoot C37.94 controllers:

Alarms

The 4-Port C37.94 interface module supports the following alarms during failure:

  • Loss of Signal (LOS)

  • Path Yellow Detection

Loss of Signal

The scenario when the receiver end receives two or more errors in eight consecutive framing patterns within 1 millisecond, the Loss of Signal (LOS) alarm is declared.

The receiver end should clear LOS after receiving eight consecutive correct framing patterns.

Figure 2. LOS at Optical Receive Port of Tele-protection Equipment



Failure Scenarios

  • During the LOS condition at its optical receive port

    At Tele-protection Equipment

    • Changes the “Yellow” bit in the transmitted optical output frames from “0” to “1”.

    At Multiplexer Equipment

    • Replaces the data bits over the higher order communications link with “All Ones,” which is commonly referred to as Alarm Indication Signal (AIS).

    • Changes the “Yellow” bit in the transmitted optical output frames from “0” to “1”

    Figure 3. LOS at Optical Receive Port of Multiplexer



  • During the loss of the higher order communications link, the multiplexer should replace the data bits in the transmitted optical output frames with “All Ones.”

Figure 4. LOS at Far End Multiplexer



Path Yellow Detection

The scenario is declared as path yellow when three consecutive received frames have the “Yellow” bit = 1 and the received signal is OK (no LOS).

The receiver clears path yellow when three consecutive received frames have the “Yellow” bit = 0 or the received signal is bad (LOS).

Loopback on C37.94 Interfaces

Loopback Description

You can use the following loopbacks on the C37.94 interfaces.

Loopback

Description

loopback local line

Loops the incoming signal in the interface using the framer’s line loopback mode. The framer does not reclock or reframe the incoming data. All incoming data is received by the interface driver.

loopback local payload

Loops the incoming signal back in the interface using the payload loopback mode of the framer. The framer reclocks and reframes the incoming data before sending it back out to the network.

loopback network line

Sets the loopback toward the network before going through the framer (line).

loopback network payload

Sets the loopback toward the network after going through the framer (payload).

Configuring Loopback

Before You Begin

Before you configure loopback, you must configure the controller and the CEM.

To set a loopback local on the C37.94 interfaces, perform the following tasks in controller configuration mode: 
 
enable
configure terminal
controller c3794 0/0/0
loopback local  line
exit
To set a loopback network on the C37.94 interfaces, perform the following tasks in controller configuration mode: 
 
enable
configure terminal
controller c3794 0/0/0
loopback network  payload
exit

Note

To remove a loopback, use the no loopback command.

Verifying the Loopback Configurations

You use the following show command to verify the loopback configuration of 4-Port C37.94 interface module:

  • Use the show controllers command to view the configurations. 

    Router# show controllers c3794 0/0/0

C3794 0/0/0 - (A900-IMA4C3794) is up
Configured Channels: 12
Peer Channels      : 12
Alarm                              : Nil
Sending Y-Alarm to Peer Device     : No
Receiving Y-Alarm from Peer Device : No
Loopback                           : local line

Additional References

Related Documents

Related Topic

Document Title

Cisco IOS commands

Cisco IOS Master Commands List, All Releases

Standards and RFCs

Standard/RFC

Title

—

There are no standards and RFCs for this feature.

MIBs

MIB

MIBs Link

IF-MIB

To locate and download MIBs for selected platforms, Cisco IOS releases, and feature sets, use Cisco MIB Locator found at the following URL:

http:/​/​www.cisco.com/​go/​mibs

Technical Assistance

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