Conference azur::mcc

Hi, (FYI)

Line Speed is not always ONLY in DNS. I'm not exactly sure of MCCs interaction
of SETs/SHOWs of line speed but the REAL line speed is dependent on the router
setup. If the LINE is set up so clock=external then line speed is solely
within DNS. But if the router has a LINE with a clock=internal then there is
a real line speed set within the router to go along with it. I suspect MCC
uses SET LINE SPEED to change the dns attribute and SET INITIAL LINE SPEED to
try to set it on the router (although DEMSA routers don't support INITIAL).

I remember QARing this a while back and the fix was for SHOW commands to check
with the router first to see if there is a real line speed, if not, check DNS
for a line speed. I never looked into how the SET feature was implemented so
part of your question still stands.

best regards,
brad...

    Hi -
    	Thanks Brad yes your memory is correct we did fix it.
        ( 1 ) I just responded to note 1074 explaining any differences.
        ( 2 ) I'll also explain it here:
             ( 1 ) if an entity returns the line speed this is what the user sees.
             ( 2 ) if the entity does not return the line speed then if this
                   is an ethernet line the DNA4-AM returns the value of 10 meg
             ( 3 ) the DNA4-AM allows you to read or write the line speed value.
                   this can be done with the following commands:
                   MCC> set node4 foo line line-n line speed line_speed_value
                   MCC> show node4 foo line line-n line speed
                   MCC> show node4 foo line line-n line speed all cha
    
    >> I understand from reading the manual that set... line speed is
    >> equivalent to a ncp set and that set... initial line speed is
    >> equivalent to a ncp def. But if this is only set in DNS, then
    >> why both?
    
        ( 3 ) Actually you can only set line speed not initial line speed.
              This is a documentation error since there is no volatile 
              and permanent database scheme in dns.
    
    
    
    
    
    
    - darryl

    Hello Darryl,
    
    
    	This also needs to be fixed in the forms and Command Line
    Interface. Set Initial Line Speed is offered there as well. Until
    now though I haven't found where the line speed topic is covered
    in the muanuals. In the back of the Phase IV manual it explains
    the difference between set and set initial. That is where I got
    the info from.
    
    
    	So, the next trick in the whole story, what is with Asynchronous
    routers. I have two with the clock set to internal, but DECmcc tells
    me the line speed is not set. In NCP help, it tells me that Line
    speed is a parameter that only has meaning for Asynchronous routers and
    must be set the same on both ends of the circuit. If I set the
    line speed, this will only be set in DNS and never affect the
    asynchronous router? (if I understand this all correctly)
    
    Julie Ann

    re: .2
.2>        ( 3 ) Actually you can only set line speed not initial line speed.
.2>              This is a documentation error since there is no volatile 
.2>              and permanent database scheme in dns.
    
    I just played around a little.
    I can SHOW the LINE SPEED - and for an Ethernet line (SVA-0 on my w/s)
    I get back the value 10000000 (which I happen to know is hardwired into
    the AM.
    
    I can issue a SHOW for the INITIAL LINE SPEED but I don't get any
    attribute value (yet!)
    
    If I try to SET the LINE SPEED, or the INITIAL LINE SPEED, I get an
    error: The entity Node4 4.427 Line sva-0  is not registered
    
    OK - that's easy - I just registered my node.
    
    Now, SHOW LINE SPEED and INITIAL LINE SPEED work fine, still.
    
    I can now SET  the LINE SPEED=100 and SET the INITIAL LINE SPEED=1000
    and I can now retrieve either, or both values, and they are both as
    SET.
    
    Of course, the reason for the line speed being stored in DNS is for
    those lines that do not "know their own speed" (or in the case of
    Ethernet lines, the default is known) we have some way of capturing the
    information.  Now as to INITIAL LINE SPEED, that has no reason to exist
    since DECnet reads its own permanent database, not the any information
    we have squirreled away. This latter attribute could probably be
    deleted without losing anything (except pages in the doc set, and text
    in the help files).
    
    Colin
    

    Hi again,
    
    	well I just played around with this too. For the synchronous router
    it all works fine. I set the line speed and show the line
    speed without problems.
    
    	Now back to my asynchronous router with the INTERNAL clock. This
    means that it should know the line speed itself, or?
    
    So I issued the directive:
    
    
    show node4 bydr03 line async-2 line speed
    
    node4 1.453 line async-2
    at 17-jul-1992 09:31:31 characteristics
    
    
    
    And I get nothing. Also, in the Forms and command line, when I
    Press PF2 after show node4 bydr03 line async-2 to get help I get
    the answer: no entity classes apply.
    
    If I try to set the line speed it works. But why didn't MCC get
    the line speed itself, if the clock was set to internal. Or have
    I missed something in this conversation.
    
    
    Julie Ann

This whole  area  is terribly complicated.  I'll give you some facts and you
can  draw  your  own  conclusions from them! First of all, ignore DECmcc and
just consider the rest of the Phase IV world:

There is a DECnet Phase IV parameter called LINE SPEED.

Some DECnet  Phase  IV  nodes implement the LINE SPEED parameter.  Others do
not.   This  decision  does  not  necessarily have any logic behind it (some
implementations  allow  internal  clocking but neither allow the speed to be
setnor  report the speed)! From memory I think that the only implementations
which implement LINE SPEED are the DECrouters (but I may be wrong).

For those  implementations  which  *do*  support LINE SPEED, sometimes it is
used  and  sometimes  it  is  ignored.   It is ignored if it has no meaning.
Asynchronous  lines  do not use clocks (that is why they are asynchronous!).
So,  for an asynchonous line, both CLOCK and LINE SPEED are ignored (if they
are  even  implemented).

Like all Phase IV parameters, LINE SPEED can be used in a permanent database
if the node supports such a thing.

The only  implementations  which  I  know  of  which support LINE SPEED (the
DECrouters) do not have a permanent database (in the usual sense).

Now consider  what  happens  when MCC gets involved.  I can't give you facts
here because I didn't write the code but my understanding is:

When you  Show  a line speed MCC tries to be helpful.  If the entity doesn't
implement  the speed MCC either works it out (the ethernet case) or looks in
the MIR for it.

When you Set a line speed MCC sets both the MIR and the entity.

I think  this  means  that  the current MCC behaviour is correct.  Both LINE
SPEED  and  INITIAL  LINE  SPEED  should  be  allowed because they both have
defined  meaning  in  Phase  IV.   If there are no implementations for which
INITIAL  LINE SPEED makes sense that doesn't necessarily mean MCC should not
support it.

The only problem in .5 is that line speed is meaningless for async lines.

Graham

    To continue what Graham described in .6
    
.6> When you  Show  a line speed MCC tries to be helpful.  If the entity doesn't
.6> implement  the speed MCC either works it out (the ethernet case) or looks in
.6> the MIR for it.
    
    The reason DECmcc is interested in knowing the line speed, even if the
    device itself does not report it or allow it to be changed, is that it
    is needed in calculations to determine the % of the line that is being
    used.
    
    Colin