Subject: Re: pilc minutes for IETF 48

From: Vernon Schryver <[email-masked]>
Date: Mon, 16 Oct 2000 19:19:23 -0600 (MDT)

> From: Bill Yeager <[email-masked]>

> ...
> Exactly the point. Most of those email users who use cell phones will send
> very short messages to one another. 

like pages or email before 21st Century SMTP.

> ...
> We are not talking ftp here or even 4xMSS worth of data. ...

No, we clearly are talking aobut FTP sized transfers.  If the issue did
not involve large streams of data, then the notion of ARQ blocking other
packets would make no sense.  The issue of re-ordering TCP segments when
there are 4 or more outstanding segments (and so 4xMSS=6000 bytes in
flight) does not make sense up except for big streams.

> ...
> And remember, real apps will soon be arriving to the phone. Smart apps. They
> will initially require HTTP/TCP/IP end-2-end and soon after use protocols like
> IMAP and SMTP. They will be light weight wrt to data use. And, they will use
> SSL/TLS for security end-2-end. They will tolerate 2 seconds of RTT, and still
> give a great user experience. THAT is cool, very cool.

That's not going to happen until phones have reasonable keyboards (or
equivalents), displays, and memory (e.g. attachments to PDA's).  When
that happens, either radio modems will have lower latencies and higher
throughputs or those wonderful applications will still not happen.
The modern Internet would not exist if it were still based on 56k leased
lines connecting IMPs ad TIPs.

No matter how cool things seem to us, users do not tolerate the delays
implied by several 1700 ms round trips for DNS followed by 3 more round
trips to set up an HTTP/TCP/IP session just to get an airline schedule or
restaurant menu so they can start to place an order.  On the other hand,
if those delays and losses go away, much of the PILC proposed improvements
to TCP, questions about ARQ below, and so forth become moot.

Vernon Schryver    [email-masked]

---

From: Bill Yeager <[email-masked]>
Date: Fri, 20 Oct 2000 10:27:34 -0700 (PDT)

Hi,

I don't want this conversation thread to distract from the TCP/IP thread which
is really what pilc is about. I'll note the following, and if you like, we can
continue offline:

| That's not going to happen until phones have reasonable keyboards (or
| equivalents), displays, and memory (e.g. attachments to PDA's).  When
| that happens, either radio modems will have lower latencies and higher
| throughputs or those wonderful applications will still not happen.
| The modern Internet would not exist if it were still based on 56k leased
| lines connecting IMPs ad TIPs.

There are phones with color and detachable keyboards much like a PDA. I-mode
has them. I too recal IMPs and TIPs having been at Stanford U. from 1974 until
1994. I am quite sure we can do a lot with even 9600  baud packet switched
networks. GPRS promises much more, and if we get 30-50kbps that is fine for
mobile phones.

As I said, applications will be different, and data demands also. Yes, there
are plans with 3G to connect laptops into these networks and do ftp. That is
where pilc comes in. 3G (WCDMA) is planned for next year in Japan. 

And, hey, lots of those wonderful Apps are already happening. They do not
depend on holding down the repeat key in a telnet session. Right, I had to
optimize that once to in my TIP code. Interactive games are a natural. Email
is easy. I've done that. Etc ...

| No matter how cool things seem to us, users do not tolerate the delays
| implied by several 1700 ms round trips for DNS followed by 3 more round
| trips to set up an HTTP/TCP/IP session just to get an airline schedule or
| restaurant menu so they can start to place an order.

Interesting. The experience on the AT&T Cellular-I CDPD network in the bay
area was not that bad(9600 baud was what was managed). DNS + HTTP/TCP/IP took
about 3 to 5 seconds on the average to set up. The connect was very quick.
There was good user feed back. I would lay in bed at night, turn on my palm
and read my email using HandWeb, with a servlet proxy, output presentation in
compact HTML, manage the session between me and the email backend (IMAP, LDAP,
SMTP). It was simple to use. Not much of a boot time, etc ... That was almost
two years ago.

Smart apps can manage latency when the net data being transferred is small(3
or 4 segments). 

So, like many of the arguments on this list we agree to disagree. For apps
this is in the spirit of let's see what really happens! I see lots of promise
and very, very soon. My hard fought battles in the trenches made me an
optimist "malgré tout!"

More offline ---

Bill