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RE: D1.1 Clause 49 State Machine comments

-----Original Message-----
From: Alex Deng [mailto:adeng@xxxxxxxxx]
Sent: Thursday, November 02, 2000 12:51 PM
To: pat_thaler@xxxxxxxxxxx
Cc: stds-802-3-hssg@xxxxxxxx; Alex Deng; Sharat Prasad
Subject: D1.1 Clause 49 State Machine comments

Hi Pat,

1.  You have changed Variables definition from "good_mt_eq_64, bad_mt_gt_32"
in D1.0
      to " good_sh_eq_64, bad_sh_gt_32", then Figure 49-8 on page 184 should
use " good_sh
      _eq_64" and "bad_sh_eq_32".

Response: Accept, I thought I fixed those.

2. Variables definition on page 183 should be "bad_sh_eq_32", not

Response: Accept.

3. Figure 49-9 on page 185 :
     a.There are two " bad_mt_eq_32" should not be there.
     b. No need for "frame_lock=true" be  there

Response: Accept a. The frame_lock=true does need to be there. The 64_good
sets good_sh_eq_64 to true to cause the Lock state machine to move to the
state.  If there was a UCT on the transition from 64_good, then it could go
to the SH_MT_INIT state where it would set good_sh_eq_64 back to false while
it tested
it again. When Frame_Lock goes true, then good_sh_eq_64 has done its job and
the transition
can occur.

4. Basically I think your state diagram in Figure 49-9 is too confuse and
    You can see from Figure 36-9 in 802.3-1998, they check if it's "cgbad"
"cggood" in every
    state, but in your diagram in Figure 49-9, you only check sync_head in
"TEST_SH" state,
    that means if you implement this state machine, you need to run atleast
frame clock.
    In my opinion, you even don't need a sync head monitor state machine,
quite simple:
                    if ( reset == true or
                          Lock_State_Machine==SLIP or
                          sh_cnt == 63 )
                                 sh_cnt <= 0;
                                 sh_invalid_cnt <=0;
                                 sh_cnt <= sh_cnt + 1;
                                 sh_invalid_cnt <= sh_invalid_cnt +
== false);
               good_sh_eq_64 <= ( sh_cnt == 63) and ( sh_invald_cnt == 0)
( sh_valid == true);
               bad_sh_eq_32 <= (sh_invalid_cnt == 31) and (sh_valid ==

Response: The code you suggest is a state machine, it is just written in a 
different language. Generally, we try to use one language for describing the

state machines in a chapter. Secondly, the state machines in 802.3 do not
define implementation. They define external behavior. This function can be 
implemented in a wide range of ways to produce this external behavior and
the state machine diagram is not intended to say anything about what kind
of clocking is used in an implementation of the funcion. I think it is
looking at this machine how to remove the Test_SH state in an
implementation, but
for purposes of the standard, doing so would crowd more transitions and I
think it would add clarity.

5. Come back to Figure 49-8 on page 184:
     I still prefer from 'NO_FRAME_LOCK" to "SLIP" should
      a. You also can see from Figure 36-9 in 802.3-1998, before it enter
           state, every time when they detect a single code error, it go
to the beginning state
      b. In your reply to my last comment, you said "It is cleaner to have
           controlled by one machine and the new machines are more closely
           but in my proposal, there is only one state machine.

Response: The code you had above is another state machine even if it is 
typed rather than drawn. The state machines I've put into 49-8 generally
execute the algorithms that were approved in the proposal for acquiring
lock. You are suggesting different algorithms. I think making a lower 
threshold for the transition from NO_FRAME_LOCK to SLIP has merit, but
I feel that it is a substantive enough change from what 802.3ae voted to
adopt that it would need logic track agreement to modify it. I did make 
substantive changes to the Transmit and Receive machines modifying the
conditions when /E/ was sent, but that was based on September's logic 
track discussion and input.


--Alex Deng
Alex Deng