Re: Keep-alive traffic (was iSCSI: more on StatRN)

[Glen Turner <glen.turner@aarnet.edu.au>]

Y P Cheng wrote:

> You are referring to TCP implementation with software.  In an
> TCP-Offload-Engine (TOE) adapter, there is no queue.  Every incoming frame,
> including the ping is served at the speed of the wire...

The BSD socket API won't allow this sort of look-ahead for a
standard TCP segment.

So for iSCSI Ping and Ping Response to be worthwhile to allow
software implementations to implement fail-over schemes, the Ping
and Ping Response should use TCP's Urgent feature to allow
out-of-order delivery of the Pings to the socket held open by the
iSCSI target?

So maybe we need to add:

   Ping and Ping Response SHOULD be marked by TCP as urgent data [RFC793].

Do we need to allow for that BSD4.2 mis-interpretation of the TCP
urgent pointer?  Does iSCSI have a Null command that we can require
as padding before the Ping commands?

-- 
 Glen Turner                                 Network Engineer
 (08) 8303 3936      Australian Academic and Research Network
 glen.turner@aarnet.edu.au          http://www.aarnet.edu.au/
--
 The revolution will not be televised, it will be digitised