[j-nsp] MLPS design considerations

[mac couil]

Hello,

I want to directly interconnect two PEs (MXseries) located into the same
site like this :


 P          P
 |          |
 PE-----PE
  |         |
 CE1      CE2

IGP is ISIS, interlink is built using xe.
PEs are MX80 in 10.2

The interconnected interfaces of each PE are members of iso, inet, ldp, mpls
families. When I send a ping from CE1 to a remote CE forwarded through the
interconnected link (---) , I observe that the payload of the icmp message
can not exceed 1464 bytes (without fragment) instead of 1472 if I do not
transit by the interconnected interfaces. I have tried to configure a hugh
MTU on theses interfaces (both sides, value of 1600 for ex) or change the
type of interfaces (xe <-> ge) but there's no change.

Well, is this design possible (I mean an interlink though "mpls interfaces"
between these two PEs) ?
if Yes, is there a special interface (or protocol) configuration/parameter
to perform this design ?

Thanks,
Muscadet