Subject: DLSw Keepalives

From: [email-masked] (Scott Barvick)
Date: Mon, 19 Sep 1994 10:46:50 -0400 (EDT)

In response to Mark's mail, the ability to know about a failed 
transport path, even if there is no data in the pipe, is a 
feature is desirable to about half of the customers who care about
the issue.  I say half because European customers, with expensive
bandwidth and possibly dial-on-demand type WANs, do not want keepalive
traffic on the WAN that they tried to get rid of with DLSw.  Mark's
options are about the same as what we identified.  More comments:

1) It should be configurable.  Implementation/configuration choice
   would determine the frequency of idle polls.

2) The 0x1D SSP message was introduced by IBM for this purpose.
   IBM could tell us about the future of this message.  The existing
   implementations which are compatible with the 6611 V1.1.1.2 should
   support receiving this message.

3) The two boxes can be running different mechanisms - transport or DLSw. 
   There should be no response expected if it is DLSw.

4) Mark suggested an INFOFRAME with no ID as a short term. Another idea
   is a bogus CANUREACH.  A bogus SAP or Mac will cause it to be 
   either dropped by the receiving router or travel harmlessly out
   on the LAN.

There has been a lot of customer interest in this feature.  It would
be good to see it addressed in a standard way so that don't have
any interoperability problems once the implementations are out there.

It is definitely too late for the first release of the spec, but
we should at least come to some agreement about the mechanisms because
customers won't wait for V2 to ask for this.

Scott
[email-masked]