Re: [manet-dlep-rg] DLEP session establishment

["Taylor, Rick" <[e-mail]>]

Sorry for the delay, I was out of office yesterday.

My thoughts:

    Router                                        Modem
    ===================================================

1)                                  TCP socket listen()

2)  <--------------------------- Peer Discovery Message
                              UDP unicast or broadcast?
                                       + Session Cookie
                                     + TCP address/port
           + Alternate reliable protocol endpoint infos

3)  TCP connect()

4)  Initialize (was Peer Offer) ---------------------->
    + Session Cookie

5)  <----------------------------------- Initialize ACK
                                       + Session Cookie
                                + Supported metric TLVs


My reasoning, often agreeing with others:

The Modem 'advertises' its DLEP support, and therefore should
be the one that listens for the TCP connect.

A cookie passed between the UDP discovery message and the TCP
connection adds a little security (is this the modem I think I am
connecting to?)  This could be extended to a full signature TLV
in a later RFC.

The Peer Discovery message could carry additional reliable
protocol endpoint information for non-TCP transports.

The Initialize ACK is the correct place to put the 'default'
metric TLVs, and is sent by the modem.

A 3-way handshake seems safer to me.

I have a question over whether the Peer Discovery message should
be unicast to a configured destination, or broadcast to all
connected peers on a TBD port.  I prefer broadcast as it is more
ZeroConf, but I can see use-cases for unicast to a configured
destination for more complex topologies.

Cheers,

Rick Taylor

> -----Original Message-----
> From: [e-mail] [mailto:manet-dlep-rg-
> [e-mail]] On Behalf Of Teco Boot
> Sent: 11 November 2013 16:29
> To: Stan Ratliff
> Cc: DLEP Research Group ([e-mail])
> Subject: [manet-dlep-rg] DLEP session establishment
>
>
> Op 11 nov. 2013, om 01:55 heeft Stan Ratliff (sratliff)
> <[e-mail]> het volgende geschreven:
>
> > Also, as to the Discovery: Here's what I'm writing up as we speak:
> >
> >
> > Router
> Modem
> > ========================================
> >                                     <------------------------ Peer
> Discovery Message
> > Peer Offer with           ------------------------->
> > unicast IP addr/
> > port for TCP connect
>
> So this is multicast reply, telling modem to connect?
> Why not TCP connect from router to modem? Makes more sense to me, the
> modem is the peer offering a service.
> Maybe add a TcpPort TLV in the Peer Discovery, this allows other than IANA
> assigned ports.
>
>
> >
> >  *Connect on TCP socket. Router has issued TCP "listen",
> >    modem issues TCP "connect" (e.g. Modem is the TCP "client",
> >    router is the TCP "server")
> >
> > Now, The modem's UDP socket can be closed.
>
> Please don't.
>
>
> > Over the TCP
> > Socket,
> >                                    <------------------------- Peer
> Initialization containing
> >
> TLVs/default values for ALL
> >
> supported metric values - all
> >
> meaning the MANDATORY ones,
> >
> plus any optional metrics (right now,
> >
> just Resources) that are supported.
>
> Yes, here the full set TLV exchange takes place. This should not be in the
> Peer Discovery. That's why I suggested to put this in the Peer Offer.
>
>
> >
> > Peer Initialization ACK ---------------------->
> > MAY contain optional
> > Layer 3 (address) TLVs
>
> I'm fine with three way handshake, not with this two way. Or use TCP
> disconnect when modem modem is not willing to accept first message from
> router.
>
> Teco
>
> >
> > .... And, everything from there is basically the same as before.
>
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