Hello,
I'm trying to setup a C4C for L2VPN but still doesn't works.
I've tried with various config file examples found on this forum without success. 
Note that we use Arris Euro Docsis 3 Modem model CM820S with software version 7.5.55
CMTS software version  is CMTS_V08.01.00.83
It's looks that my problem is not related to L2VPN but to BPI as when I add PrivacyEnable to a working CM config file without L2VPN the modem stuck
in "dhcpV4done" state and  "Privacy=Initializing" 
Do I need to configure something on the headend ? We currently don't use shared-secrect  may this is the problem ...
Any clue  to solve this issue ?
Best regards
tbu-C4c-1# show cable modem  xxxx.xxxx.xxxx detail
15/14-10/11     CM xxxx.xxxx.xxxx (e8.3e.fc) D1.0 State=DhcpV4Done D1.0/atdma PrimSID=6693
Cable-Mac= 4,  mCMsg = 1   mDSsg = 1   mUSsg = 1, RCS=0x00000003 TCS=0x0000000c
Timing Offset=770    Rec Power= 9.00 dBmV Proto-Throttle=Normal
Uptime=  0 days  0:00:55 IPv4=10.12.177.223   cfg=vpn2.cfg
LB Policy=0  LB Group=0    Filter-Group CM-Down:0   CM-Up:0
Privacy=Initializing
MDF Capability= N/A                  MDF Mode= N/A
u/d     SFID    SID State Sched    Tmin       Tmax    DFrms   DBytes    CRC    HCS  Slot/Ports
u     223182   6693 Activ BE          0          0        0        0      0      0   10/11
d     223183  *6870 Activ             0          0        0        0                 15/14
L2VPN per CM: (Disabled)
Current CPE=0, IPv4 Addr=0, IPv6 Addr=0          Max CPE=32, IPv4 Addr=0, IPv6 Addr=0
tbu-C4c-1# show cable modem  xxxx.xxxx.xxxx
Jun 26 05:25:03
Interface                              DOC
(DS-US)       Mac   Bonded State       SIS      Qos      CPE  MAC address     IP Address
------------- ----- ------ ----------- --- ------------- ---  --------------- ---------------------------------------
15/14-10/11   4            DhcpV4Done  1.0                 0  xxxx.xxxx.xxxx  10.12.177.223
              Total    Oper  Disable    Init  Offline
---------------------------------------------------------
Found             1       0        0       1        0