nanog mailing list archives
Re: Caps (was Re: AT&T UVERSE Native IPv6, a HOWTO)
From: Jeff Kell <jeff-kell () utc edu>
Date: Mon, 9 Dec 2013 01:02:54 -0500
On 12/9/2013 12:48 AM, Jay Ashworth wrote:
A 3270 that took 5 seconds of delay and then *snapped* the entire screen up at once was perceived as "faster" than a 9600 tty that painted the same entire screen in about a second and a half or so. Don't remember who it was either, but likely Bell Labs.
This is a "screen/block" mode I/O issue versus a character-mode one. And the "screen/block" I/O won't start until the whole screen data is there, so there is an initial delay. The character-mode variant will paint portions of the screen as the data arrives. Similar anomalies exist on input... the screen/block mode is buffered locally and proceeds normally; while the character mode version has to transit the WAN link, whatever it may be. I won't argue that one is better than the other, depending on your link speed (transmitting a whole screen will incur longer delays than transmitting individual fields, though admittedly it happens "less" often). But the user perception goes a long way... I have seen advantages to both, having done serial termainal applications from back to the 1970s, and won't argue one way or the other. You choose your poison. With 3270 you have little choice other than "full screen" transactions. For other ASCII terminal interfaces, you could optimize the individual fields (while paying the "full screen" price). There are "user perceived" throughput values, "transaction perceived" throughput values, and "application perceived" throughput values. And very rarely did the three equal out for every application :( Jeff
Current thread:
- Re: AT&T UVERSE Native IPv6, a HOWTO, (continued)
- Re: AT&T UVERSE Native IPv6, a HOWTO Owen DeLong (Dec 05)
- Re: AT&T UVERSE Native IPv6, a HOWTO Mikael Abrahamsson (Dec 05)
- Re: AT&T UVERSE Native IPv6, a HOWTO Phil Karn (Dec 05)
- Caps (was Re: AT&T UVERSE Native IPv6, a HOWTO) Mark Radabaugh (Dec 06)
- Re: Caps (was Re: AT&T UVERSE Native IPv6, a HOWTO) Michael Thomas (Dec 06)
- Re: Caps (was Re: AT&T UVERSE Native IPv6, a HOWTO) cb.list6 (Dec 06)
- Re: Caps (was Re: AT&T UVERSE Native IPv6, a HOWTO) Mark Radabaugh (Dec 06)
- Re: Caps (was Re: AT&T UVERSE Native IPv6, a HOWTO) Phil Karn (Dec 08)
- Re: Caps (was Re: AT&T UVERSE Native IPv6, a HOWTO) Dave Crocker (Dec 08)
- Re: Caps (was Re: AT&T UVERSE Native IPv6, a HOWTO) Jay Ashworth (Dec 08)
- Re: Caps (was Re: AT&T UVERSE Native IPv6, a HOWTO) Jeff Kell (Dec 08)
- Re: Caps (was Re: AT&T UVERSE Native IPv6, a HOWTO) Gary Buhrmaster (Dec 08)
- Re: Caps (was Re: AT&T UVERSE Native IPv6, a HOWTO) Valdis . Kletnieks (Dec 09)
- Re: Caps (was Re: AT&T UVERSE Native IPv6, a HOWTO) Dave Crocker (Dec 09)
- Re: Caps (was Re: AT&T UVERSE Native IPv6, a HOWTO) Jay Ashworth (Dec 09)
- Re: Caps (was Re: AT&T UVERSE Native IPv6, a HOWTO) Jared Mauch (Dec 09)
- Re: Caps (was Re: AT&T UVERSE Native IPv6, a HOWTO) Jay Ashworth (Dec 09)
- Re: Caps (was Re: AT&T UVERSE Native IPv6, a HOWTO) Mark Radabaugh (Dec 09)
- Re: AT&T UVERSE Native IPv6, a HOWTO Owen DeLong (Dec 06)
- Re: AT&T UVERSE Native IPv6, a HOWTO Brandon Ross (Dec 08)
- Re: AT&T UVERSE Native IPv6, a HOWTO Nikolay Shopik (Dec 09)