Conference 7.286::fddi

922.0. "FDDI to Ethernet Failover Issue - Cross - Posted in LATMASTER conference" by GIDDAY::STANISLAUS () Thu Apr 08 1993 01:19

	A system (6000 or 9000) has DEMFA and DEMNA. The FDDI and the Ethernet
LAN's are connected via DEFCN (DECconcentrator 5xx) and DEFEB (DECbridge 6xx).
Effectively the systems have their two LAN controllers connected via DEFCN and
DEFEB. The idea is FDDI fails, protocols (LAT, DECnet) can be failed over to 
Ethernet either manually or via an automatic command procedure.

The LAT acrchitecture I believe does not allow dual rail operation if the dual
rails are connected together via bridges. 

DECnet Ph IV also does not support two LAN circuits on one Node that have these
two LAN circuits bridged together.

LAVc apparently does not have the above limitation.

	So my customer is running DECnet and LAT on FXA0 (DEMFA) on all his
four systems (two 6000-420 and two 9000-210 systems). But if the DEMFAs and or
the DEFCN or DEFEB or fibre breaks he wants to be able to switch to Ethernet
via the DEMNAs.

	So ,the customer unplugs the fibre from the DEMFAs bulkhead and wants to
do a delete the LAT link on FXA0 under LATCP and do a CREATE a new LAT link on
ETA0. But he is unable to delete the LAT link from FXA0. Hence he is unable to
create a new LINK on ETA0. This is a customer's ACCEPTANCE TEST STEP before 
accepting all the FDDI products he purchased. Has such an Acceptance Test
been carried out at other sites on 6000s or 9000s to see the failover from
FDDI to Ethernet.

	To try DECnet manual failover, he unplugs the fibre as above, turns
off fxa-0 line and circuit and clears fxa-0 line and circuit, sets mna-0 line
and circuit and turns on mna-0 line and circuit and away he goes and everything
works fine.    

	He has DEMFA firmware version 1.4, VMS version 5.5-2, CSCPAT0511 ver
3.3 LAT patch installed and FXDRIVER patch VAXPHV02_U2055.A installed and still
has the problem.

Alphonse

    
    	Alphonse,
    
    	Could you supply a little more info for us naive conferencers
    that havn't had the luxury of playing with FDDI yet.
    
    	I don't undestand why the link has to be deleted on the FDDI
    cannot the link state just be SET off?
    
     	And why can't a link already created for the  Ethernet in an off
    state just be set on?
    
    						Bill

Bill,

	I came across a TIMA STARS article which suggested to do so what I did
as against what you and I wanted to do. It suggested to delete and create the
link rather than keep state off and then turn on. So I ended up doing what the
TIMA STARS article suggested. May be you can contact Mike at ROYALT::RASPUZZI
to throw some light on this. he may know the reason for that article. 

	What concerned me was that no other site/customer tried to do what my
customer did as part of accepting testing the FDDI equipments.

	I am on holidays till 19th Apr 93. I will look at this then.

Alphonse