Conference 7.286::fddi

An FDDI adapter will be treated by the software essentially like another
Ethernet port; DECnet will know (you will tell it) which to use depending on
what circuit and line are defined and is in an "on" state; there will be
different device names in NCP for the Ethernet and FDDI adapters. 

If the Ethernet backbone is also connected or bridged into the FDDI
concentrator, so they are part of the same extended LAN, then under DECnet
Phase IV, only one of the two lines/circuits can be on at one time.  None of
the nodes would require DECnet routing functionality, since the Ethernet is
bridged to the FDDI. 

If the Ethernet backbone is not connected to the FDDI concentrator, and if you
need DECnet on both sides, then at least one VAX system would need to be a
DECnet router, and it would have both circuits/lines turned on; the others
could be end nodes, and would have only one circuit/line in use. 

    Thanks for the answers!
    
    Actually the FDDI and Ethernet would NOT be joined together. The idea
    is to use the FDDI only as a high speed interconnect between the 3 VAXs
    because the Ethernet backbone is expected to be very busy, and they
    would like to take some of the load off the Ethernet and feed it thru the
    FDDI connection. There would be nothing else on the FDDI ring, at least
    at the beginning.
    
    I'm not a SW person, and what bothers me (what I don't know) is how you
    would tell the systems which traffic to go Ethernet and which FDDI.
    
    I could probably get some of this info from the local gurus, but
    they're not available right now, so if you could elaborate just a
    little more on this, I'd really appreciate!
    
    Thanks
    
    Rolf
    

    What kind of traffic are3 you talking about?
    
    Decnet only?
    LAT?
    Clusters?
    Other?
    
    	For DECnet Phase IV, it is treated just like another Ethernet. I'm
    not sure what is possible here, but it is the same as whatever is
    possible with the 3 6000's having a private Ethernet amongst
    themselves.
    
    	For clusters,.. what you want will happen automagically.
    
    	For LAT,.. Again,. its whatever is possible with Ethernet.
    
    	For other applications/products, it depends on their capabilities.
    
    	Sorry not to be of more help. Maybe with some more details, I,
    	or others, can give you more useful feedback.
    
    							/Bill
    

   
   	 Bill
   
   	 I don't know if your use of the word was deliberate or accidental, 
         but I adore the term "automagically"....
   
   	       ... could this be a new addition into our language ?!
   
   	 Brilliant - made my day !
   
   	 Rog

    
    Automagically is indeed a brilliant term! I think I've seen it before
    though...
    
    Well, at this point nobody is really sure what kind of traffic there
    will be. We are at present designing the network (20 floor DECconnect
    mainly) but it involves the backbone also. 
    
    Each VAX "owns" its own vertical backbone with a specific application:
    
    a PRODUCTION-LAN, a DEVELOPMENT-LAN (these two will have LAT service
    exclusively) and the third is a PCSA-LAN. These three LANs will branch
    off the main Ethernet backbone via LANBridges-150. That main backbone 
    (the one to which the 3 systems are connected) will of course "see" the
    traffic of all 3 application LANs, and they are aware that that is not
    the ideal situation, but they will live with it until traffic gets too
    heavy, and then they can implement a second ethernet controller in each
    system, to keep application traffic separate from the main backbone.
    
    The 3 VAXs will not be configured as a cluster.
    
    Actually at this point we were only concerned with the physical
    validity of the dual connectivity between the 3 systems, and since
    that seems to be no problem, we'll just tell them that it's OK if
    they really want it. 
    
    Thanks again for the help.
    
    Rolf

    Rolf,
    
    	Just be carefule about what you tell them for load balancing
    or whatever. I'll let anotehr expert comment,.. but it is my belief
    that DEcnet won't do what you want,.. at least not Phase IV DECnet...
    
    re 'automagically'
    
    	Can't remember where I first heard that,.. might have been Paul
    Koning,.. but I too loved it so much I've forgotten how to spell
    that other word :-)
    
    							/Bill
    

   
   	 I think the basic answer to your question is a YES for both DECnet 
         phase IV and V. 
   
   	 Multiple controllers can be installed in Phase IV nodes but in order 
         for the system to use both controllers simultaneously you would need 
         to configure as a Full Function (routing) node. If the system is set 
         up as an End node only (non-routing) then only one of the multiple 
         controllers (circuits) can be switched on at any one time.
   
   	 Under Phase V, you can configure an End system to be a multi-homed 
         node.  This equates to being an end node with the ability to use 
         multiple circuits at the same time but not to route between them.
   
   	 In any event the LAT and LAST protocols are non-routable anyway so 
         the routing function would not be used in this context.
   	 
   	 If the two LANs were bridged then the network would work but some 
         attention to circuit costings would be needed in order to determine 
         the "least cost" (preferred) route for the attached systems to use. 
         This option may be useful if you were thinking of providing 
         resilience to failure in the network.
   
   	 Some considerations.....
   
   	 If you're worried about the amount of data traffic becoming too much 
         for the "backbone" to cater for, have you considered using FDDI to 
         provide sufficient capacity - especially if you're proposing to use  
         Open DECconnect structured building wiring. 
   
   	 If you're not clustering the VAXen how much data is likely to be 
         passed between them ? If it is not much then the Ethernet may 
         support this requirement. If there is lots of data then use FDDI for 
         that side too !
   
   	 Hope this is of use !
   
   	 Rog

>>         Under Phase V, you can configure an End system to be a multi-homed 
>>         node.  This equates to being an end node with the ability to use 
>>         multiple circuits at the same time but not to route between them.

   	 Rog

	You probably mean Multi-circuit End system. Multi-homing is
	another feature where a node has more than one area address.

Cheers

	Walter.

hi rolf

if the vax 6000s are routing nodes each circuit has a COST parameter associated
with it. any given logical link to a particular destination chooses the LEAST
COST path to the destination.

in your case since the two lans are disjoint you should give the lowest cost to
the fddi link (say 1) and a higher cost to the ethernet links (like 10) 

now all logical links between the 3 6000s will always use the fddi link. only
logical links to destination not reachable via the FDDI will use the ethernet.

it is not possible to have lets say file transfers use the fddi links and
cterm traffic use the ethernet.

this does bring up the point as to whether the DECnets will change their
default costs. now ethernet links default to 1.

    I appreciate all the answers given so far, and I have learned quite a
    bit from them. 
    
    As I mentioned in some earlier reply, at the moment we were really only
    concerned with the physical validity of having the Ethernet and FDDI
    ports hooked up at the same time (which seems to be OK, based on all
    the answers).
    
    The customer most likely will start out using only the Etrhernet-Only
    solution, but he will feel safe if he knows he can implement the FDDI
    "relief" solution, if he starts seeing too much traffic building up on
    the Ethernet, or maybe even the FDDI-at-both-ends solution!
    
    Thanks again
    
    Rolf