| Title: | FDDI - The Next Generation |
| Moderator: | NETCAD::STEFANI |
| Created: | Thu Apr 27 1989 |
| Last Modified: | Thu Jun 05 1997 |
| Last Successful Update: | Fri Jun 06 1997 |
| Number of topics: | 2259 |
| Total number of notes: | 8590 |
A customer is planning on the following network and I wish to ask some
questions relating to failover and backup paths.
This customer has two VAX9000, two VAX 6420 and one VAX8530 on an
Ethernet. Two VAX 9000 and one VAX 6420 belongs to one CI cluster. The VAX 8530
and the other VAX 6420 is on another CI cluster. The customer has MI clusters
on both the above clusters with many many sattelite nodes.
Now the customer is getting FDDI installed.
I have already installed one DEMFA (XMI to FDDI adapter) in each of the
VAX 9000 and VAX 6420 systems, but the FDDI cables from the bulkhead to the
DECconcentrator 500 are not connected as yet from any of these four systems.
I have also installed a DECconcentrator 500 and two DECbridge 620 in a
FDDI ring. The low power FDDI module in the DECconcentrator 500 has 4 ports and
will be connected to the four DEMFAs above in a week's time. Let us call one
DECbride 620 (with 3 Ethernet ports) as Bridge 1 and the other similar DECbridge
620 as Bridge 2. Now Bridge 1 has one Ethernet going to a Segment A, one Ethernet
going to Segment B and one Ethernet going to Segment C. Bridge 2 has one Ethernet
going to Segment A (same as A above) , one Ethernet going to segment D and one
Ethernet port not used. Segment A has all the above large VAXs -
two VAX 9000s, two VAX 6420 and One VAX 8530. Segment B and Segment C above are
going to be interconnected with a LANbridge 200. Segment B and Segment C both
have many many Workstations and Servers and satellite nodes and Translans, etc.
etc. Segment D is just a pilot development segment with a few Workstations.
The question is when the DEMFAs get connected to the DECconcentrator
500, naturally you cannot run DECnet over the DEMFA and DEMNA (VAX 9000)
or DEMFA and DEBNA (VAX 6000), because the two LAN's (FDDI LAN and Ethernet
LAN are bridged together by the DECbridge 620s). I presume if you run LAT
over both (DEMFA and DEMNA for example) you may get Multiple Node Errors logged
by the Terminal servers, because it will see the AA-00-04-00-xx-yy address over
the FDDI and Ethernet as well, but may work. God knows what will happen with
SCA (LAVc), Pathworks, UCX, and a few other hundred protocols that the customer
is running. I am not sure if this was sold to the customer as an automatic
failover to Ethernet if FDDI fails (DECconcentrator or DEFMA or Fibre cable
failure). Has this been done before ? If it is all confusing I can send a FAX
of the Network to anyone who is interested in similar situations.
______________ <--Lanbridge 200 between--> __________________
Ethernet Seg B Seg B and Seg D Ethernet Seg D
to DB620 #1 to DB620 #2
| |
| |
v v
-------------------
||-----------------
|| ||
|| ||
DB620 DB620
#1 #2
Ethernet _________ || ||
Seg D to DB620 #1 || ||
Pilot Seg D ----DC500--------|
------------------
| | | |
| | | | <--- Fibre cables fom system to DC500
v v v v GOING TO BE CONNECTED NEXT WEEK.
to the DEFMAs in the VAX 9000 and VAX 6420 systems.
D D D D
E E E E
M M M M
F F F F
A A A A
| | | |
9 9 6 6 8
0 0 4 4 5
0 0 2 2 3
0 0 0 0 0
| | | | |
D D D D D
E E E E E
M M B B B
N N N N N
A A A A A
| | | | | NOW EXISTING
| | | | | <--- Ethernet Drop cables to H4005
v v v v v Note 8530 has no FDDI board.
___________________________________________________Ethernet Seg A.
connected to
DB620 #1 and #2 as
well
I can send a FAX if required.
Alphonse
| T.R | Title | User | Personal Name | Date | Lines |
|---|---|---|---|---|---|
| 721.1 | DAS version of DEMFA - Is there such a thing | GIDDAY::STANISLAUS | Fri Sep 25 1992 04:14 | 5 | |
Is there a version of DEMFA to connect to two concentrators for failover/backup pupose. This was going to be my question in .0 as well. Alphonse | |||||
| 721.2 | LAVC and DECnet | STAR::PARRIS | CI,DSSI,SCSI,FDDI:Any port in a StorME | Fri Sep 25 1992 10:01 | 14 |
I can cover a couple of the questions: As long as you're running VMS 5.4-3 or later (which you need for support of the DEMFAs anyway...), you'll be fine as far as VAXcluster protocol traffic is concerned: VMS will automatically enable use of all the available LAN adapters. LRPCOUNT needs to be raised if you need to use large packets on FDDI, however. For DECnet, it's true that you can only use one LAN adapter at a time when multiple adapters are connected to the same extended LAN. You do that by either only defining the desired device mnemonic in NCP (i.e. purge circuit and line MNA-0 and define MFA-0 if you want to use the DEMFA instead of the DEMNA), or by defining all but the desired one with STATE OFF. Perhaps someone else can help with LAT and PATHworks... | |||||
| 721.3 | MSBCS::KALKUNTE | Ram Kalkunte 293-5139 | Sat Sep 26 1992 19:36 | 16 | |
If the sales folks have sold FDDI as an auto-failover mechanism from
Ethernet, that is dead wrong. Do something about it, now. If they need
such mechanisms, that has to be supported by the applications they run;
the protocols will not.
UCX can support both FDDI and Ethernet devices simulataneously, but as
different IP addresses. As .-1 notes, DECnet has a different set of
idiosyncrasies. There are reasons for why they work this way.
Pathworks runs on top of DECnet or TCP/IP (UCX). So whether or not you
can have both devices "connected" to the same extended LAN at the same
time depends on the protocol you run it on. But even when both devices
are connected, there is no guarantee that the failover machanism is
automatic, unless the application makes it that way.
There is no such thing as a DAS DEMFA and I don't see how this can be
of use; the concentrator should be a much more reliable component.
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