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Conference netcad::hub_mgnt

Title:	DEChub/HUBwatch/PROBEwatch CONFERENCE
Notice:	Firmware -2, Doc -3, Power -4, HW kits -5, firm load -6&7
Moderator:	NETCAD::COLELLADT

Created:	Wed Nov 13 1991
Last Modified:	Fri Jun 06 1997
Last Successful Update:	Fri Jun 06 1997
Number of topics:	4455
Total number of notes:	16761

560.0. "Hub900 Backplanechannel config question" by ZUR01::SCHNEIDERR () Mon Dec 13 1993 13:00

Hello,


If I select a independant backplanechannel (IMB), I can't deside whitch pins 
on the connectors are used for that connection. But there are situations, I need
to use the IMB on the upper connector?
How do I do that?

Example:

I put in the DECrepeater 90FS (DEFNI) whitch is a halfhigh module and connect it
to an IMB. Because of the size of the module it must be the IMB on the upper
connector.
Now I put in an other fullsizemodule, lets say a WGB200 and connect one of the
Ethernet-ports to the same IMB, if it is alowed to do that. Than it must be 
the IMB on the upper connector, right?

Now if I do it in the reverse order. I put in the fullsizemodule first, connect 
it to an IMB (some pins, somewhere on a connector are used, lets assume on the lower
one). Then I put in the DECrepeater 90FS (DEFNI) and connect it to the same 
IMB. Can I do this, or is there a limitation I don't know about? Is the 
pin-configuration for that IMB automatic reconfigured, that
pins from the upper connector are used and I don't have to care about?



Thanks Roland

T.R	Title	User	Personal Name	Date	Lines
560.1	it's automagic...	QUIVER::SLAWRENCE		`Mon Dec 13 1993 15:23`	34
	It's all automagic. The MAM queries each module to discover its interfaces and the signals each interface can use. When you connect a backplane port to a segment, the MAM finds a set of signals that can be used for the segment that interface can use. If that search fails it checks to see if reconfiguring all interfaces on the backplane would result in all connections being made (all existing ones plus the one you just asked for); if so, it does the reconfiguration. So, in your examples: If you connect the small module to the IMB first, that IMB would be allocated on the upper connector (the only possibility). When you connect the large module, it would connect to the same signals; no problem. If you connect the large module to the segment first, it might be allocated on any flex channel. When you attempt to connect the small module the MAM would figure out that only the upper channel would work and if the IMB was not already there it will order the large module interface to reconfigure. Note that if you were to attempt to connect a second small module to an IMB _different_ from an IMB that another small module is already on, the request will be rejected because even a total reconfiguration would not satisfy all connections (the first module would be undisturbed). Actually, the MAM will anticipate this situation if the hub contains at least one FDDI-capable module (including the bridge). Since the FDDI modules can't use the flex channel on the upper connector, it will be allocated first for Ethernet segments because it is the least flexible.
560.2	Thanks a lot for the answer	ZUR01::SCHNEIDERR		`Tue Dec 14 1993 11:08`	0
560.3	So the Hub stop for a while?	OSAV20::IZUTANI	Kenji Izutani,Tech.Consul.,CSEC,DEC-Japan	`Wed Dec 15 1993 21:27`	9
	RE:.1 So I can't stop thinking of the time duration for the backplane to reconfigure. How long will it take to reconfigure the backplane? And will the hub stop working for a moment? Kenji Izutani
560.4	Your mileage may vary ;-)	QUIVER::GALLAGHER		`Wed Dec 15 1993 22:48`	13
	>So I can't stop thinking of the time duration for the backplane to >reconfigure. > >How long will it take to reconfigure the backplane? And will the hub stop >working for a moment? We haven't quantified "how quick" yet. In general, the answer is "very quick". So quick, in fact, that nobody has really worried too much about it. How quick is it for a person to swap cables in order to do a LAN reconfiguration? Hub reconfiguration will be much faster than manual reconfiguration. -Shawn
560.5		QUIVER::SLAWRENCE		`Thu Dec 16 1993 11:27`	10
	I've gotten this question enough times now that I suppose I'll have to go set up an experiment to measure it. Nothing is disturbed on the backplane until the solution is already known, and then the operations all take place very quickly. We have a monitor board that displays activity on a flex channel with a LED and the reconfiguration shows as a very brief flicker (some fraction of a second, I would guess). Watch this space...