| T.R | Title | User | Personal
Name | Date | Lines |
|---|
| 144.1 | My five-penny worth | COMICS::WOODWARD | Smile! | Thu Sep 27 1990 05:42 | 13 |
|
1) This is wrong, M-M connections are 'illegal' (they could be any other port
type, A, B or typically S)
2) There are two types of CON, dual-attached and single-attached. The DAC
will have A, B and M ports. The SAC will have multiple M and an S ports
(the S port if used will connect the SAC to a DAC to enter the dual
ring) This agrees with the SMT draft spec.
3) Assuming 2) above is the truth, the statement is correct
4) I think you're correct, it sounds better as 'bridge', we use adapter to
mean a host system connection
|
| 144.2 | B=S? | OSAV20::IZUTANI | Kenji Izutani,Tech.Consul.,CSEC,DEC-Japan | Thu Sep 27 1990 06:35 | 13 |
| > 2) There are two types of CON, dual-attached and single-attached. The DAC
> will have A, B and M ports. The SAC will have multiple M and an S ports
> (the S port if used will connect the SAC to a DAC to enter the dual
> ring) This agrees with the SMT draft spec.
>
> 3) Assuming 2) above is the truth, the statement is correct
But I think there is one product, i.e. DECconcentrator500, from DEC. This CON
can be used for both DAC and SAC, isn't it. In this case, will we call port B
of DC500 as DAC and port S as SAC though they are same MIC?
Kenji
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| 144.3 | A con has two flavors - DAC and SAC | LEVERS::CIARFELLA | Saabless and happy | Thu Sep 27 1990 10:13 | 62 |
|
> 1. In Fifure 2-11 on page 2-21, there are Port M to Port M connections.
> Are they correct?
My figure 2-11 does not show any M to M connections. It shows a
Dual Attached concentrator with an A,B, and 3 M ports. The M ports
are connected to three boxes of type S. The dotted lines between
the M ports mean that there could be other M ports which were not
shown.
> 2. On page 3-3, there are sentences as follows;
>
> " CON ports can be type A,type B,type M or type S."
> ~~~~~~~
> I think CON has no port S.
There are two flavors of concentrators, Dual Attached (DAC) and
Single Attached (SAC). Single Attached concentrators have a single
S port and multiple M ports. Dual Attached concentrators have one
A and B port each and multiple M ports. Dual attached provide direct
connection to the trunk ring or to the tree. SACs provide connections
to the leaves of the tree.
> "Type S ports are part of a SAC. They connect the SAC ..."
> ~ ~~~~ ~~~
> I think SAC should be SAS or type S should be type B.
The book is correct. This paragraph is describing how and where
a SAC can connect to the ring.
> 3. On page 3-5, in the paragraph 3.3,
>
> ".. through the B port(S port on a SAC), flow..."
> ~~~~~~~~~~~~~~~~~
> This seems to be confusing. I think this sentence is unnecessary.
I'll try to clarify the statement. When a DAC is being connected as
part of the tree, its B port is connected to the M port of the
concentrator above it. If the concentrator is a SAC in this case,
its S port would connect to the M port of the other concentrator.
Frames would enter the concentrator through the S port, then out of
and back into each M port (one at a time, of course) and then back
out the S port.
> 4. On page 4-6, in the paragraph 4.3.2,
>
> "FDDI entities in the adapter include..."
> ~~~~~~~
> This should be "bridge".
Yes, in this paragraph it should be bridge.
> Is my understanding that CON has no port S correct?
No. As mentioned before, Single Attachment concentrators have an S port
instead of an A,B combination.
I hope that this explains things for you.
Paul C
|
| 144.4 | Our con is a DAC | LEVERS::CIARFELLA | Saabless and happy | Thu Sep 27 1990 10:15 | 4 |
|
re: .2 The DECConcentrator 500 can only function as a Dual Attachment
Concentrator. There is no option available to make it a SAC.
|
| 144.5 | | KONING::KONING | NI1D @FN42eq | Thu Sep 27 1990 10:25 | 19 |
| Re .2 re .4: it's often said that "a concentrator in the tree acts like
a SAC". This is NOT CORRECT. The rules under which a DAC operates in
the tree are DIFFERENT from those for a SAC.
The definitions:
1. If it has M ports, it's a concentrator.
2. If it doesn't, it's a station.
3. If it has an S port, it's Single Attached.
4. If it has A and B ports, it's Dual Attached.
So therefore our concentrator is a DAC. It remains a DAC no matter where
in the network it is used.
The correct statement is that a SAC can be used only in a tree, while a DAC
can be used both in a tree and in a dual ring. This should give you an
idea about why we didn't bother building a SAC...
paul
|
| 144.6 | different book? | COMICS::WOODWARD | Smile! | Thu Sep 27 1990 11:15 | 14 |
| re .3
> My figure 2-11 does not show any M to M connections. It shows a
> Dual Attached concentrator with an A,B, and 3 M ports. The M ports
> are connected to three boxes of type S. The dotted lines between
> the M ports mean that there could be other M ports which were not
> shown.
Which book? I've got the June 1990, ek-dfsld-sd-001 and the figure 2-11
definitely shows the 3 M ports on the DAC connected to 1 S and 2 M ports.
One of us must have an 'old' version, and if it's you then the new version,
which is probably going to customers, looks incorrect.
Steve
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| 144.7 | Preliminary copy from may is correct | LEVERS::CIARFELLA | Saabless and happy | Thu Sep 27 1990 17:45 | 8 |
|
Whoops - my copy is the prelim from May. I would've thought that
errors get fixed, not introduced, when going from a preliminary to
published copy.
I better get the new and 'improved' version.
Paul C
|
| 144.8 | I understood. | OSAV20::IZUTANI | Kenji Izutani,Tech.Consul.,CSEC,DEC-Japan | Thu Sep 27 1990 23:00 | 10 |
| Thanks many to all replies.
So Digital has implemnted only DAC, and DAC can be used similarly as SAC, using
port B instead of port S.
SLD describes FDDI standards in general and DEC hasn't implemented all of the
standards. Its the reason why I'm confused.
I hope to see the Table 1-2 of next release SLD including those difference.
thanks again.
Kenji
|