| T.R | Title | User | Personal
Name | Date | Lines |
|---|
| 2031.1 | FDDI config questions | HGOVC::SHUMCF | | Fri May 03 1996 13:05 | 28 |
| Hello,
I have some questions on the config. of FDDI ports, i.e. A,B,M & S.
Basically, I know port A & B used in dual ring config and port M & S
used in tree config. However, I found some connection rule not
understood posted in note 2340 Hub_mgnt as follow:
Port A Port B Tree/Peer State
------ ------ --------- -----
S S Peer thru
S M Tree c_wrap_B (tree prefer)
M S Tree c_wrap_A (tree prefer)
In the 1st case, will it means there are 2 FDDI paths for the DAS station
i.e. port A to S and port B to S and will it be any communciation
between these 2 FDDI paths.
In the 2nd case, when will we use port A to port S and port B to port M?
can you give me some real application.
In the 3rd case, why we can use port B to port S because they are both
sink ports?
Besides, can we configure port A as port M and port B as port S?
Thanks in advance,
CF Shum
HK NS
|
| 2031.2 | | NETCAD::STEFANI | | Fri May 03 1996 16:47 | 22 |
| >>In the 1st case, will it means there are 2 FDDI paths for the DAS station
>>i.e. port A to S and port B to S and will it be any communciation
>>between these 2 FDDI paths.
In this case you'll have three nodes (2 SAS and 1 DAS) connected as
S-A B-S. You'll have communication between all three nodes. However,
should the DAS node fail, you'll obviously lose connectivity between
the two SAS nodes.
>>In the 2nd case, when will we use port A to port S and port B to port M?
>>can you give me some real application.
>>
>>In the 3rd case, why we can use port B to port S because they are both
>>sink ports?
Cases 2 and 3 are very similar. It's just a matter of whether the A or
B port has the tree connection. I can't recall the FDDI rules at the
moment, but I believe the A-M or B-M connection will be preferred and
the other connection will not be made. Should the tree connection be
removed, the other connection will be made.
- Larry
|
| 2031.3 | | 35356::RABAHY | dtn 471-5160, outside 1-810-347-5160 | Fri May 03 1996 17:13 | 2 |
| B-M is the prefered path. If it is up then the A port will be in standby. At
least it is if it is A-M. I don't know exactly what B-M, A-S means.
|
| 2031.4 | | NETCAD::STEFANI | | Fri May 03 1996 17:51 | 8 |
| >>B-M is the prefered path. If it is up then the A port will be in standby. At
>>least it is if it is A-M. I don't know exactly what B-M, A-S means.
I know that B-M will be the preferred path in a dual-homing (B-M and
A-M) configuration. The tree/peer configuration (B-M and A-S -OR
B-S and A-M) always confuses me as to who wins.
/l
|
| 2031.5 | still not understand | HGOVC::SHUMCF | | Sat May 04 1996 07:28 | 8 |
| Sorry for my ignorance on FDDI config, do you mean one of the dual
homing connection (B-M or M-A) happened on a DAS device and the other
port can be used as tree config (A-S or B-S) as in case 2 & 3. If so,
would you explain it in more details. Besides, can we use any
combination of port A,B,M & S ?
Thanks/regards,
CF Shum
|
| 2031.6 | | KALI::STEFANI | | Mon May 06 1996 08:55 | 16 |
| >>Sorry for my ignorance on FDDI config, do you mean one of the dual
>>homing connection (B-M or M-A) happened on a DAS device and the other
>>port can be used as tree config (A-S or B-S) as in case 2 & 3. If so,
>>would you explain it in more details. Besides, can we use any
>>combination of port A,B,M & S ?
I'm saying that in the dual homing connection (B-M and A-M) the primary
connection is B-M and the standby connection is A-M. That way, should
the B-M connection fail (B port fails, M port fails, or cable fails)
the A-M connection will activate and you'll retain your network
connection.
DAS port configurations in which one is a tree connection and the other
is a peer connection is more complicated, and not as common.
/l
|
| 2031.7 | still have problem onf FDDI config rule | HGOVC::SHUMCF | | Mon May 06 1996 11:51 | 28 |
| I understand the FDDI config will be complicated but it must have some
guideline to follow. However, I can only get the info about A-B and B-A
in dual-ring config, and M-A and M-B in dual-homing config, and using
the combination of the above for dual-ring of tree. For those A-S, B-S
and M-S config, I'm really not understand. Would you please explain when
we will use this config or give me a pointer about this FDDI rule.
Since our customer purchased 4 x Gigaswitch/FDDI recently, I gave him a
table of FDDI config rule published inside the Digital Open DECconnect
Application Guide. The table is shown as below:
A B M S
A - yes - yes
B yes - yes -
M - yes - yes
S yes - yes -
From my understanding, it seems Master/Slave config, i.e A & M are
master and B & S are slave. Then, how about dual-homing of M-A. Also
if A-S is valide, how about B-S not shown on the above table. It all
makes me confused. Please help me out of this problem and give me a
full FDDI config rule or pointer.
Thanks a lot,
CF Shum
|
| 2031.8 | Tree connections are preferred over dual ring connections | NPSS::MDLYONS | Michael D. Lyons DTN 226-6943 | Mon May 06 1996 14:50 | 67 |
| Re: .7
...that matrix is oversimplified. The simplest thing to say is
"don't do things like that", but if you insist:
From the FDDI System Level Description:
This node
PHY port A B M S
Other A No Rule 1 Yes Yes
Node B Rule 2 No Yes Yes
M Rule 3 Yes - note 1 No Yes
S Yes Yes Yes Yes
Rule 1: PHY B of "this node" accepts connection to PHY A of "other
node" if:
o PHY A of "this node" is not connected, or
o PHY A of "this node" is connected to PHY B or PHY S of another
node
Rule 2: PHY A of "this node" accepts connection to PHY B of "other
node" if:
o PHY B of "this node" is not connected, or
o PHY B of "this node" is connected to PHY A or PHY S of another
node. See also Note 2.
Rule 3: PHY A of "this node" accepts the connection to PHY M of "other
node" if:
o PHY B of "this node" is not connected, or
o PHY B of "this node" is connected to PHY A or PHY S of another
node. See also note 2.
Note 1: Backup tree connection (dual homing)
The connection of PHY B of "this node" to PHY M of "other node"
always takes precedence over the connection of PHY A of "this node" to
PHY M of another node.
When a connection between PHY A of "this node" and a PHY M or PHY B
of another node exists, it is disabled when PHY B of "this node"
connects to PHY M of "other node".
If the connection breaks between PHY B of "this node" and PHY M of
"other node", the connection is reestablished between PHY A of "this
node" and PHY M of another node.
Note 2: Tree connections are preferred over dual ring connections
Tree connections are preferred over dual ring connections when only
one of two connections may be accepted.
The connection of PHY A or B of "this node" to PHY M of "other
node" always takes precedence over the connection of the remaining PHY
(A or B) of "this node" to PHY A or PHY B of another node.
The connection is disabled between the remaining PHY (A or B) of
"this node" and PHY A or PHY B of another node when PHY A or PHY B of
"this node" connects to PHY M of "other node".
...any typos are mine
MDL
|
| 2031.9 | | NPSS::MDLYONS | Michael D. Lyons DTN 226-6943 | Mon May 06 1996 14:59 | 5 |
| ..note that that is "our" documentation. If you want the gory
details, the true source is the actual specs. I think most humans
would find them unappealing.
MDL
|
| 2031.10 | thanks for the FDDI table | HGOVC::SHUMCF | | Tue May 07 1996 11:07 | 5 |
| Thanks for your clarification on the use of FDDI port, I sure it can
give a more firmer answer to the customer.
Thanks again,
CF Shum
|