Re: [manet-dlep-rg] TCP clients, servers, and discovery (WAS: Re: notes DLEP meeting @ IETF88)

[Henning Rogge <[e-mail]>]

Stan,

maybe you should think about the argument again... it doesn't matter
if the radio or the router sends the UDP discovery packet... it
doesn't matter either if the radio is the TCP server or client.

In all cases both radio and router will handle UDP and TCP... and most
likely nobody will care about the few lines of codes.

Many modern radio vendors implement their radio software by buying an
embedded operation system including a full TCP/IP stack... or they
just use an open source one, which also will already have a posix
compatible IP stack. They wont have to implement it themselves.

Henning Rogge

On Thu, Nov 14, 2013 at 6:53 PM, Stan Ratliff (sratliff)
<[e-mail]> wrote:
> I thought about not sending this email… perhaps I should have abided that urge, but what-the-heck… ;-)
>
>
> On Nov 14, 2013, at 11:12 AM, Teco Boot <[e-mail]> wrote:
>
>>
>> Op 14 nov. 2013, om 16:20 heeft Henning Rogge <[e-mail]> het volgende geschreven:
>>
>>> I still prefer the UDP peer discovery sent by the radio.
>>
>> +1
>> Followed by a TCP SYN response sent by router.
>> This enables set up of DLEP sessions without the UDP ignition packet. Routers can send the TCP SYN to the modem if they have knowledge on the modem IP address.
>>
>> Teco
>>
>>
>>>
>>> Henning Rogge
>>>
>
> If this winds up being the path taken, it means that modems are going to wind up juggling UDP and TCP sockets, including a TCP listen() socket. Multi-socket select() dispatch loops; managing listen queue depth, and dealing with non-blocking sockets (so that the select works) are also on the horizon for the modem implementers. And all of this to get a 1-hop discovery mechanism running - I wonder what the path length (libraries INCLUDED) for that is, just to avoid a single line of config (that being, the address and port of the other end of the connection)?
>
> The alternative I was shooting for, from the modem perspective, was along the lines of:
> 1. Open a (blocking? non-blocking? don't care) UDP socket.
> 2. Receive the discovery packet. Close that socket? Keep it open? Your call.
> 3. Open a TCP socket. Issue connect(), from the info you got (and/or derived) from the discovery packet.
> 4. Flail away, sending and receiving actual DLEP protocol packets!
>
> I'm beginning to think we need to pop the champagne corks and congratulate ourselves for (partially) designing something no one in their right mind would implement…
>
> Stan
>
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