[j-nsp] logical router with physical Interco

[juniper light]

Hi guys,
I would like to use M10 to simulate 3 PE, using logical-routers ( Junos
8.4R4.2 )

I connected 2 fastethernet back-to-back, link are UP. but when I tried
configuring vlan-id , I cannot ping from one Logical router to the other :

first scenario using Vlan-tagging :

set logical-routers PE2 interfaces fe-0/3/0 unit 23 vlan-id 123
set logical-routers PE2 interfaces fe-0/3/0 unit 23 family inet address
10.0.123.1/30
set logical-routers PE3 interfaces fe-0/3/1 unit 23 vlan-id 123
set logical-routers PE3 interfaces fe-0/3/1 unit 23 family inet address
10.0.123.2/30
set interfaces fe-0/3/0 vlan-tagging
set interfaces fe-0/3/1 vlan-tagging

admin at M10> show interfaces terse
Interface               Admin Link Proto    Local                 Remote
...
fe-0/3/0                up    up
fe-0/3/0.123            up    up   inet     10.0.123.1/30
fe-0/3/0.32767          up    up
fe-0/3/1                up    up
fe-0/3/1.123            up    up   inet     10.0.123.2/30
fe-0/3/1.32767          up    up
fe-0/3/2                up    up
fe-0/3/3                up    up

Second scenario without Vlan-tagging :

set logical-routers PE2 interfaces fe-0/3/0 unit 0 family inet address
10.0.123.1/30
set logical-routers PE3 interfaces fe-0/3/1 unit 0 family inet address
10.0.123.2/30


admin at M10> ping logical-router PE2 10.0.123.2 source 10.0.123.1
PING 10.0.123.2 (10.0.123.2): 56 data bytes
nothing happen ......

admin at M10> show interfaces terse
Interface               Admin Link Proto    Local                 Remote
...
fe-0/3/0                up    up
fe-0/3/0.0              up    up   inet     10.0.123.1/30
fe-0/3/1                up    up
fe-0/3/1.0              up    up   inet     10.0.123.2/30
fe-0/3/2                up    up
fe-0/3/3                up    up


admin at M10> show chassis hardware
Hardware inventory:
Item             Version  Part number  Serial number     Description
Chassis                                xxxx             M10
Midplane         REV 03   710-001950   xxx            M10 Backplane
Power Supply A   Rev 05   740-002497  xxx          AC Power Supply
Display          REV 04   710-001995   xxx            M10 Display Board
Routing Engine   REV 07   740-007603   xxx      RE-3.0
FEB              REV 08   710-003310   xx            E-FEB
FPC 0                                                    E-FPC
  PIC 1          REV 05   750-003163   xxx            1x G/E, 1000 BASE-SX
  PIC 3          REV 06   750-002992   xxx           4x F/E, 100 BASE-TX
FPC 1                                                    E-FPC
Fan Tray                                                 Rear Left Fan Tray

Any idea about that ?

Thanks for your help,

Kind Regards
// Mounir