Re: RFC 4591 and RFC 4349

At 01:35 PM 7/22/2010 +0200, Javi Muñoz wrote:

>b) FRoPW (DLCI mode):
>
>           C1                            C2
>  [ FR A ]----[ LCCE 1 ]------[ LCCE 2 ]----[ FR B ]
>
>               <------ L2TP FRoPW ---->
>         <---->                        <---->
>        FR traffic                   FR traffic
>
>...
>In this mode, the L2TP cloud behaves as if it were a FR switch.
>
>===



>b) FRPWs: according with your explanation, I would understand the next one:
>
>                                           ¿ ?
>                                            |
>                                            |
>                                           \ /
>DTE - PE/DCE <== FRPW ==> PE/DCE - ¿DTE? <== Data Network ==> DCE - DTE
>  <Q.933>                     <Q.933>                          <Q.933>
>  <-------------------------- FR VC -------------------------------->
>  <DLCI_1> [DLCI switching] <DLCI_2>     [ DLCI switching ]   <DLCI_3>
>           [DLCI_1 => DLCI_2]            [DLCI_2 => DLCI_3]
>
>    However, it would not be possible, due to the access nodes to the data network must be DCEs.

I think you are overthinking this.

First, note that my drawings did not include any references to
DCE or DTE on purpose because that is an implementation issue
out of scope for L2TP.

I imagine that if someone wanted to use FR over an L2TP PW,
the LCCEs (or the devices feeding into the LCCEs) would have
to be DCE or DTE as needed. There are many devices out there
that can be configured as either DCE or DTE so this shouldn't
really be a problem.

HTH,
-Ignacio