[Search for users] [Overall Top Noters] [List of all Conferences] [Download this site]

Conference 7.286::fddi

Title:	FDDI - The Next Generation

Moderator:	NETCAD::STEFANI

Created:	Thu Apr 27 1989
Last Modified:	Thu Jun 05 1997
Last Successful Update:	Fri Jun 06 1997
Number of topics:	2259
Total number of notes:	8590

146.0. "FDDI Availability and filtering" by TOOIS1::MIRGHANE () Mon Oct 01 1990 13:19

We need the following information for a big project in the space area
implementing some 100 worstations with servers and central computing systems.

1: FDDI availability

As we understand the FDDI cable is very reliable because of dual ring. Then
using SAS connected to concentrators enables to remove systems without
impacting the network.
The problem is however coming from the concentrators. We understand that if 2
concentrators fail then the network is split into 2 subnetworks. 

How can we avoid such a problem. Is there a way by using dual concentrators
that could prevent this from happening? or is there another way to avoid
disrupting the network?

2: Filtering network traffic.

If I have a "cluster" of workstations connected to servers using a concentrator
then this concentrator is connected to an FDDI ring in order to talk to other
systems. will the concentrator filter the traffic and allow only non local
traffic to cross to the FDDI ring or do I have to add a filtering bridge?

T.R Title User Personal
Name Date Lines

146.1 Answers AKO569::JOY Get a life! Mon Oct 01 1990 15:21 18

T.R	Title	User	Personal Name	Date	Lines
146.1	Answers	AKO569::JOY	Get a life!	`Mon Oct 01 1990 15:21`	18
	1. The concentrators are very reliable and two failing at the same time is a very remote possibility. But there si the possibility that this would happen. If the two concentrators that fail are next to each other on the ring, you wouldn't get a segmented network since the next neighbor on each side would wrap and you'd still have one network. If they weren't next to each other, then the only way you could maintain connectivity would be by designing a tree topology using cascaded concentrators which are dual-homed and hope for the best. You can probably cover about 90% of the possible failures this way, but I don't believe there is any way to provide 100% non-segmentation if you lose more than one dual-attached station. 2. You need a filtering bridge. The concentrator provides no filtering capability. This would mean the local traffic would have to be on an Ethernet or else use a third-party FDDI-FDDI router/bridge. Debbie

    1. The concentrators are very reliable and two failing at the same time
    is a very remote possibility. But there si the possibility that this
    would happen. If the two concentrators that fail are next to each other
    on the ring, you wouldn't get a segmented network since the next
    neighbor on each side would wrap and you'd still have one network. If
    they weren't next to each other, then the only way you could maintain
    connectivity would be by designing a tree topology using cascaded
    concentrators which are dual-homed and hope for the best. You can
    probably cover about 90% of the possible failures this way, but I don't
    believe there is any way to provide 100% non-segmentation if you lose
    more than one dual-attached station.
    
    2. You need a filtering bridge. The concentrator provides no filtering
    capability. This would mean the local traffic would have to be on an
    Ethernet or else use a third-party FDDI-FDDI router/bridge.
    
    Debbie