Time-division multiplexing (TDM) is a method of transmitting and receiving independent signals over a common signal path by means of synchronized switches at each end of the transmission line so that each signal appears on the line only a fraction of time in an alternating pattern. (Source: wikipedia). Nowadays, there are some subscriber that still use TDM circuit for interconnection their network with service provider. If you are vendor working with NOKIA/Alcatel-lucent or you are operator that use 7705 SAR in your edge network. It's better to know. How to configure, and how to verify your MPLS transport can carry TDM Traffic as well.


For the basic concept TDM, I hope you're done. So for this step, We will focus with how to make the service that emulate TDM traffic. If it's the first time with TDM. I recommend to read the article or maybe information from ITU-T G series.

Overview

Nokia 7705 SAR-8 has media dependent adapter that support TDM channel. and Nokia 7705 SARF has 16 port TDM channel. That port can be used as Service Access Port (SAP) to carry TDM service over MPLS (Usually called Circuit Emulation Service) or in Nokia we called CPIPE Service. Or that port can be used as Interface port that interconnection with TDM Transport Carrier, like SDH Network Transport or Microwave link that used E1/T1 interface.

Note to remember, TDM need time synchronization to deliver the traffic. and it's mandatory, without time synchronization, TDM traffic can't deliver correctly, maybe some issue will be triggered, like overun and underun, FAS, (Please refer to TDM alarm information for further information )



Hardware Preparation

7705 SAR-8 and SARF have different module to running TDM, For 7705 SAR-8, we need module to running TDM service, there are:
  1. 16-port T1/E1 ASAP Adapter card 
  2. 32-port T1/E1 ASAP Adapter card
  3. 12-port Serial Data Interface card
  4. 6-port E&M Adapter card
  5. 2-port OC3/STM1 Channelized Adapter card
  6. 4-port OC3/STM1 Channelized Adapter card
  7. 4-port DS3/E3 Adapter card 
  8. 8-port Voice & Teleprotection card
  9. 4-port T1/E1 and RS-232 Combination module 
  10. 8-port FXO Adapter card 
  11. 6-port FXS Adapter card

7705 SARF has different TDM interface, the port is integrated with the box, and the port seems like ethernet port but have their own pin configuration.
Usually there are some separation, to make differentiation between customer domain and provider domain.  Maybe some of you call it Point Of Interconnection (POI). We need (Digital Distribution Frame) DDF for this. DDF is termination point device that connect between Service Provider Device with Customer Device or Router device with Transport Device. 

The LSA DDF have two part, customer pin (Cable From Customer) and router pin (Cable From SAR-8 and SAR-F). To make it connected, TX customer should be facing with RX router and vice versa. From SAR-8 that using E1/T1 16 Port module, we need E1/T1 cable. It has 2 cable contain TX and RX like picture below.
The mapping pin and color cable from E1/T1 cable is like below :
To mapping cable E1/T1 to LSA DDF, there are some rule should be followed:
  • One LSA Block serve 5 E1 Channel/Port
  • Each Port has Tx and Rx
  • Each Sub-bundle cable contains 4 cable. 
  • Each Sub-bundle cable contains 2 port
  • Each Tx and Rx using 2 cable from E1/T1 cable, for mapping you may see the table above
  • Tx and Rx must be cross pair, it means, If the RX cable using white-blue, so the Tx cable using Turquoise-Violet (Please see the table to help you understand)
  • On The LSA, mapping the Rx cable first ( MAP-1) then continue with the Tx cable (MAP-2)
From the mapping table and the rule, we know the mapping behaviour for E1/T1 in one LSA block,

How about the 7705 SAR-F port? Like mentioned before, E1/T1 ports in SAR-F are integrated port. There are 16 port like ethernet port but have different pin. It's easy to mapping on the LSA block. Because they no need to E1/T1 cable. Usually, you may use utp cat-5 or something else. Below, the pin configuration on SAR-F E1/T1 port.




Pre-Configuration Procedure

Before we try next step, make sure IGP, MPLS, RSVP (if need it) were established. (I'll try to explain to build mpls network in other post).

Below the Topology,

To achieve the synchronization transport. TDM Customer Equipment must have same clock source with TDM Transport. In Nokia 7750-SAR8 and Nokia 7750-SARF, to receive clock information. We need to configuration system sync clock under system sync-if-timing configuration. The configuration is like below (Note: in this case, I use external as clock source, it's mean, we use clock source device as sync time reference) :
A:LAB-7705-SAR8# configure system sync-if-timing 
Before editing, you must type begin,
*A:LAB-7705-SAR8>config>system>sync-if-timing# begin 
After that, you type external, it's means you want to use external source clock reference.
            ref-order external ref1 ref2
            external
                input-interface
                    no shutdown
                exit
            exit
Then Save the configuration change
A:LAB-7705-SAR8# /admin save
For external clock port position, in your Nokia 7705-SAR8 put in CSM (Control Switch Module). See the red circle below. One port as input then other port is output to other device or to standby CSM (Note: Nokia 7705-SAR8 using 2 CSM, for redundancy).
 
But, in 7705-SARF, there is different. SAR-F box. The port that use to receive external port is on board. (SAR-F is single board device).

Verify the clock sync running well, do command
A:LAB-7705-SAR8# show system sync-if-timing 
The source clock system status must uup and the system status CSM A must Master Lock, It's mean the clock is stable and sync with clock source. In other means, the clock quality is good. Verify with command "show system sync-if-timing"
*A:LAB-7705-SAR8# show system sync-if-timing 

===============================================================================
System Interface Timing Operational Info
===============================================================================
System Status CSM A                : Master Locked
    Reference Input Mode           : Non-revertive
    Quality Level Selection        : Disabled

Reference Order                    : external ref1 ref2

Reference Input 1   
    Admin Status                   : down
    Configured Quality Level       : none
    Rx Quality Level               : unknown
    Qualified For Use              : No
        Not Qualified Due To       : disabled
    Selected For Use               : No
        Not Selected Due To        : disabled
    Source Port                    : None

Reference Input 2      
    Admin Status                   : down
    Configured Quality Level       : none
    Rx Quality Level               : unknown
    Qualified For Use              : No
        Not Qualified Due To       : disabled
    Selected For Use               : No
        Not Selected Due To        : disabled
    Source Port                    : None

External Reference Input   
    Admin Status                   : up
    Configured Quality Level       : stu
    Qualified For Use              : Yes
    Selected For Use               : Yes
    Type                           : 2048Khz-G703
    Impedance                      : 50-Ohm

External Reference Output   
    Type                           : 2048Khz-G703
===============================================================================
*A:LAB-7705-SAR8# 

Configuration Procedure

In configuration procedure, we will do several step, like configuration access port, in Nokia we call it SAP (Service Access Point). Configuration Between SAR-F and SAR-8 is same. The Port Allocation like below:

SAR-8 Port SAR-F Port
port 1/1/1.1 port 1/1/1.1
The port configuration in SAR-8
A:LAB-7705-SAR8>config>port# info 
----------------------------------------------
        tdm
            e1 
                framing e1-unframed
                channel-group 1
                    encap-type cem
                    no shutdown
                exit
                no shutdown
            exit
        exit
        no shutdown
----------------------------------------------
A:LAB-7705-SAR8>config>port# 
The port configuration in SAR-F
A:LAB-7705-SARF>config>port# info 
----------------------------------------------
        tdm
            e1 
                framing e1-unframed
                channel-group 1
                    encap-type cem
                    no shutdown
                exit
                no shutdown
            exit
        exit
        no shutdown
----------------------------------------------
A:LAB-7705-SARF>config>port# 
Creating cpipe service:using satop-e1, we use this because we deliver E1 unframed traffic, not channelized traffic.
 CPIPE Service in 7705-SAR8
A:LAB-7705-SAR8# configure service cpipe 11 vc-type satop-e1 create 
A:LAB-7705-SAR8>config>service>cpipe# info 
----------------------------------------------
            description "satop unframe to sar-f"
            sap 1/1/1.1 create
            exit
            spoke-sdp 11:11 create
            exit
            no shutdown
----------------------------------------------
A:LAB-7705-SAR8>config>service>cpipe# 
CPIPE Service in 7705-SAR8F
A:LAB-7705-SARF# configure service cpipe 11 vc-type satop-e1 create 
A:LAB-7705-SARF>config>service>cpipe# info 
----------------------------------------------
            description "satop unframe to sar8"
            sap 1/1/1.1 create
            exit
            spoke-sdp 11:11 create
            exit
            no shutdown
----------------------------------------------
A:LAB-7705-SARF>config>service>cpipe# 
After create the service, you may verify using several command below:
1. Make sure the service up (administrative and operation), to check, do command: /show service service-using cpipe
2. Make sure SAP and SDP tunnel is up. do command :  /show service id <service id> base
3. Make sure no error on SAP, using command: /show service id 11 sap <port id>.<channel group> detail
A:LAB-7705-SARF# /show service service-using cpipe 

===============================================================================
Services [cpipe] 
===============================================================================
ServiceId  Type      Adm  Opr  CustomerId Service Name                         
-------------------------------------------------------------------------------
11         Cpipe     Up   Up   1                                               
12         Cpipe     Up   Up   1                                               
-------------------------------------------------------------------------------
Matching Services : 2
-------------------------------------------------------------------------------
===============================================================================
A:LAB-7705-SARF# show service id 11 base 

===============================================================================
Service Basic Information
===============================================================================
Service Id        : 11                  
Service Type      : Cpipe               VLL Type          : SAToPE1
Name              : (Not Specified)
Description       : satop unframe ke sar8
Customer Id       : 1                   
Last Status Change: 07/14/2013 11:52:52 
Last Mgmt Change  : 07/14/2013 11:52:52 
Admin State       : Up                  Oper State        : Up
MTU               : 1514                
Vc Switching      : False               
SAP Count         : 1                   SDP Bind Count    : 1
 
-------------------------------------------------------------------------------
Service Access & Destination Points
-------------------------------------------------------------------------------
Identifier                               Type         AdmMTU  OprMTU  Adm  Opr 
-------------------------------------------------------------------------------
sap:1/1/1.1                              cem          1514    1514    Up   Up  
sdp:11:11 S(192.168.200.4)               n/a          0       1546    Up   Up  
===============================================================================
A:LAB-7705-SARF# show service id 11 sap 1/1/1.1 detail 

===============================================================================
Service Access Points(SAP)
===============================================================================
Service Id         : 11                       
SAP                : 1/1/1.1                  Encap             : cem
Description        : (Not Specified)
Admin State        : Up                       Oper State        : Up
Flags              : None
Multi Svc Site     : None                     
Last Status Change : 07/14/2013 11:52:52      
Last Mgmt Change   : 07/14/2013 11:39:56      
Sub Type           : regular                  
Split Horizon Group: (Not Specified)
 
Admin MTU          : 1514                     Oper MTU          : 1514
Ingr IP Fltr-Id    : n/a                      Egr IP Fltr-Id    : n/a
Ingr Mac Fltr-Id   : n/a                      Egr Mac Fltr-Id   : n/a
Ingr IPv6 Fltr-Id  : n/a                      Egr IPv6 Fltr-Id  : n/a
tod-suite          : None                     qinq-pbit-marking : n/a
Ing Scheduler Mode : 4-priority               Egr Scheduler Mode: 4-priority
                                              
                                              
Endpoint           : N/A                      
 
Acct. Pol          : None                     Collect Stats     : Disabled
 

-------------------------------------------------------------------------------
QOS
-------------------------------------------------------------------------------
Ingress qos-policy : 1                        Egress qos-policy : 1
Shared Q plcy      : n/a                      Multipoint shared : Disabled
-------------------------------------------------------------------------------
Sap Statistics
-------------------------------------------------------------------------------
Last Cleared Time     : N/A                    

                        Packets                 Octets
Forwarding Engine Stats
Dropped               : 0                       0                              
Off. HiPrio           : 569094                  145688064                      
Off. LowPrio          : n/a                     n/a                            

Queueing Stats(Ingress QoS Policy 1)
Dro. HiPrio           : 0                       0                              
Dro. LowPrio          : n/a                     n/a                            
For. InProf           : 569094                  145688064                      
For. OutProf          : 0                       0                              

Queueing Stats(Egress QoS Policy 1)
Dro. InProf           : n/a                     n/a                            
Dro. OutProf          : n/a                     n/a                            
For. InProf           : n/a                     n/a                            
For. OutProf          : n/a                     n/a                            
-------------------------------------------------------------------------------
Sap per Queue stats
-------------------------------------------------------------------------------
                        Packets                 Octets
 
Ingress Queue 1 (Priority)
Off. HiPrio           : 569094                  145688064                      
Off. LoPrio           : n/a                     n/a                            
Dro. HiPrio           : 0                       0                              
Dro. LoPrio           : n/a                     n/a                            
For. InProf           : 569094                  145688064                      
For. OutProf          : 0                       0                              
 
Egress Queue 1
For. InProf           : n/a                     n/a                            
For. OutProf          : n/a                     n/a                            
Dro. InProf           : n/a                     n/a                            
Dro. OutProf          : n/a                     n/a                            
-------------------------------------------------------------------------------
CEM SAP Configuration Information
-------------------------------------------------------------------------------
Endpoint Type          : Unstruct. E1     Bit-rate                   : 32
Payload Size           : 256              Jitter Buffer (ms)         : 5
Jitter Buffer (packets): 5                Playout Threshold (packets): 3
Use RTP Header         : No               Differential               : No
Timestamp Freq         : 0                CAS Framing                : No CAS
Effective PDVT         : +/-2.0 ms        
 
Cfg Alarm      : stray malformed pktloss overrun underrun 
Alarm Status   : 
-------------------------------------------------------------------------------
CEM SAP Statistics
-------------------------------------------------------------------------------
                         Packets           Seconds           Events
Egress Stats
Forwarded             :  599374                                               
Dropped               :  0                                                    
Missing               :  0                                                    
Reordered Forwarded   :  0                                                    
Underrun              :  713678                              1                
Overrun               :  0                                   0                
Misordered Dropped    :  0                                                    
Malformed Dropped     :  0                                                    
LBit Dropped          :  0                                                    
Error                 :                    0                                  
Severely Error        :                    0                                  
Unavailable           :                    699                                
Failure Count         :                                      1                
Jitter Buffer Depth   :  2                                                    

Ingress Stats
Forwarded             :  599377                                               
Dropped               :  0                                                    
===============================================================================
A:LAB-7705-SARF# 

Okay, This is simple configuration how to Make CPIPE to carry TDM traffic from customer over MPLS netwrok in Nokia 7705-SAR