| T.R | Title | User | Personal
Name | Date | Lines |
|---|
| 1899.1 | | NPSS::MDLYONS | Michael D. Lyons DTN 226-6943 | Tue Dec 12 1995 14:02 | 27 |
| > 1. When both links are operational, "B" is active and "A" is in
> standby mode, running Link Confidence Test. If link "B" fails, it
> should fail over to "A" but when the primary link B is resumed, will it
> switch back to link "B" automatically??
Yes
> 2. When there is a path switch over, will the NMS detect and send an
> alarm?
What NMS? ...you could probably program a NMS to do this if the NMS
allows you to.
> 3. Can you use the NMS to manually set the secondary link "A" as the
> primary link?
No
> 4. This FDDI technique that provides a standby path in case a
> connection fails, is it similar to Spanning Tree when it detects a
> loop?
No - there is no loop detection or intelligence about the topology.
There is no checking that you are connected to the same ring.
MDL
|
| 1899.2 | More dual Homing Questions | HGOVC::SOONDERAM | | Wed Dec 13 1995 02:03 | 45 |
| Thank you very much for the quick response!
Additional questions:
--------------------
1st Dual FDDI Ring-----1st FDDI Concentrator(M)----
I \
I ---(A)
2 GIGAswitch DECswitch900EF
I ---(B)
I /
2nd Dual FDDI Ring-----2nd FDDI Concentrator(M)----
Question to the above config:
----------------------------
As you can see, the DECswitch900EF is configured (dual homing) to
two separate FDDI Concentrators and the two Concentrators to two separate
FDDI daul rings for redundancy.
1. Since the (B) link will always be active (dual homing), When there is a
total 2nd dual ring failure (primary and secondary) and it is not the
M--B link itself, will the standby (A) link become active??
2. If it does, how do they do it?
3. Since the link (M---B) between Concentrator and DECswitch is still
good but the main path to the servers is down, if it does, Is the
intelligence to sense that coming from the DECswitch.
4. When using Polycenter Netview and Hubwatch as NMS, is there an error
message when (dual homing) link B switches over to link A? Can you tell
which link is active at any given time? Do you have to wait until it
is polled by the NMS or is the alarm sent instantaneously?
5. If the above NMS (Netview and Hubwatch) can detect the link switch
over and send out an error message, do you have to manually zoom down
different levels to find out exactly what is happening??
Thanks in advance.
|
| 1899.3 | | 35356::RABAHY | dtn 471-5160, outside 1-810-347-5160 | Wed Dec 13 1995 11:19 | 30 |
| re .2:
Interesting. Classically, with dual homing, the two concentrators are on the
same ring. When a concentrator fails, the alternate path is used.
+----------------------------------------------------+
| |
| +---+----------+---+ +---+----------+---+ |
+-| A | FDDI CON | B |----------| A | FDDI CON | B |-+
+---+---+------+---+ +---+---+------+---+
| M | | M |
+---+ +---+
| |
+---------+ +-----+
| |
+---+ +---+
| A | | B |
+---+-------------+
| DECswitch 900EF |
+-----------------+
With your configuration, if a concentrator doesn't fail then the alternate path
won't be used. If the path between the active concentrator and the GIGAswitch
is lost then the DECswitch will *not* kick over to the other concentrator.
Why did the path between the concentrator and the GIGAswitch fail? Supposedly
there are two geographically distinct routes between them.
Have you considered that in the given configuration the DECswitch 900EF is a
single point of failure.
|
| 1899.4 | | NPSS::MDLYONS | Michael D. Lyons DTN 226-6943 | Fri Dec 15 1995 11:38 | 48 |
| > 1. Since the (B) link will always be active (dual homing), When there is a
> total 2nd dual ring failure (primary and secondary) and it is not the
> M--B link itself, will the standby (A) link become active??
No. - the network will be partitioned.
> 2. If it does, how do they do it?
They don't. ...if you want this to survive partitioning, you need to
eliminate the rings at the top of the tree. I.E. Dual home the
concentrators to the GIGAswitch/FDDI systems too. You still have a few
cases where you can get partitioning, but it's cut down by a few...
> 3. Since the link (M---B) between Concentrator and DECswitch is still
> good but the main path to the servers is down, if it does, Is the
> intelligence to sense that coming from the DECswitch.
...see above
> 4. When using Polycenter Netview and Hubwatch as NMS, is there an error
> message when (dual homing) link B switches over to link A? Can you tell
> which link is active at any given time? Do you have to wait until it
> is polled by the NMS or is the alarm sent instantaneously?
The default combination of our products and our NMS do not give you
an asynchronous notification when this happens. You would have to set
traps up (product dependent - if such a trap were supported) or do
polling.
As far as the GIGAswitch/FDDI system is concerned, there is no trap
which provides the asynchronous notification. You can do polling to
see if the status has changed.
If you have Hubwatch set up to do polling, you should be able to
see the LEDs change on the PMDs.
> 5. If the above NMS (Netview and Hubwatch) can detect the link switch
> over and send out an error message, do you have to manually zoom down
> different levels to find out exactly what is happening??
I don't know anything about how traps are handled with Netview.
Using Hubwatch with the GIGAswitch/FDDI system, you can see that the
LEDs have changed - it doesn't cause any type of alarm condition, so if
that's what you're looking for, you'll have to look elsewhere.
Hubwatch doesn't do traps...
MDL
|