Hi,
I think it is worth looking into figure 2 in draft-ietf-ipv6-3gpp-recommend-02.txt.
Unless this figure gets corrupt in the mail you'll see that there are 2 different IP
layers and the cellular host draft is talking about the IP layer between MS and GGSN.
/Peter
------
| |
| App |- - - - - - - - - - - - - - - - - - - - - - - - -(to app peer)
| |
|------| -------------
| IP |- - - - - - - - - - - - - - - - - - - - - - -| IP |->
| v4/6 | | v4/6 |
|------| ------------- ------------- |------ |
| | | \ Relay / | | \ Relay / | | | |
| | | \ / | | \ / | | | |
| | | \ / | | \ / | | | |
| PDCP |- - -| PDCP\ /GTP_U|- - -|GTP_U\ /GTP_U|- - -|GTP_U | |
| | | | | | | | | | |
|------| |------|------| |------|------| |------| |
| | | | UDP |- - -| UDP | UDP |- - -| UDP | |
| | | |------| |------|------| |------| |
| RLC |- - -| RLC | IP |- - -| IP | IP |- - -| IP | |
| | | | v4/6 | | v4/6 | v4/6 | |v4/6 | |
|------| |------|------| |------|------| |------|------|
| MAC | | MAC | AAL5 |- - -| AAL5 | L2 |- - -| L2 | L2 |
|------| |------|------| |------|------| |------|------|
| L1 |- - -| L1 | ATM |- - -| ATM | L1 |- - -| L1 | L1 |
------ ------------- ------------- -------------
UE UTRAN SGSN GGSN
> -----Original Message-----
> From: Dr. Subrata Goswami [mailto:[EMAIL PROTECTED]]
> Sent: den 28 maj 2002 19:19
> To: [EMAIL PROTECTED]
> Subject: RE: MLD comments on cellular host drafts - seeking feedback
>
>
> Hesham, SGSN "sees" the mobile's traffic - as it passes through it.
> SGSN being an L2 device for IP, it is capable of doing L2
> switching (if
> the 3gpp spec does not prohibit and the vendor innovates). The
> following is the protocol stack for the SGSN (user plane, from the TS
> 23.060 you referred, btw the 3GPP web-site needs better navigation).
>
> ------------- ---------------
> |SNDCP GTP-U| |GTP-U GTP-U |
> |LLC UDP | |UDP/IP UDP/IP|
> |BSSGP IP | |AAL5 L2 |
> |FR L2 | |ATM L1 |
> |L1 L1 | ---------------
> ------------
> GPRS-SGSN UMTS-SGSN
>
> From the above, it is possible to make GPRS-SGSN to mcast as it
> detunnels the IP packets.
>
> In case of UMTS, the same functionality can be in the UTRAN.
>
> Subrata
>
>
> -----Original Message-----
> From: Hesham Soliman (ERA) [mailto:[EMAIL PROTECTED]]
> Sent: Tuesday, May 28, 2002 4:44 AM
> To: 'Dr. Subrata Goswami'; [EMAIL PROTECTED];
> [EMAIL PROTECTED]
> Subject: RE: MLD comments on cellular host drafts - seeking feedback
>
> > > Sorry, that isn't the correct model.
> >
> > Then it is the correct model, if you read my email it was
> > mentioned that
> > SGSN is an L2 device. Also as one SGSN supports multiple
> > mobiles - it needs
> > to know somehow which mobiles are part of an mcast group
> > and that can be
> > done by MLD.
>
> => No. The model is not correct as we tried to
> explain. The SGSN does not 'see' the mobile's
> traffic and does not do any 'L2 switching'.
> So your conclusion is not correct.
>
> For more information, please refer to 3GPP
> specs: TS 23.060 (any revision will explain
> this issue clearly).
>
> Hesham
>
>
>
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