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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

2099.0. "DB900MX and DSW900EF Spanning tree failures." by CSC32::B_LEWIS () Mon Mar 13 1995 13:37

  I have a customer with a DEChub 900 with a DB900MX in slot 4 and and a 
DSW900EF in slot 7. Both of the bridges have their A and B ports pointed to
the back plane and have a connection to the FDDI lan on the hub. Port three
on both modules have a connection to the thinwire lan on the hub back plane.

  I know this makes a loop in the network and should cause one of the port three
connections to go to standby mode. This is not happening the FDDI port on the 
900EF is going to standby. I can force a change by disconnecting the port three
lan connection on the lan interconnect screen in hubwatch. But when we reconnect
the thinwire to the port three on the 900EF both port  three's on both modules
go to forwarding and none of the ports go to standby.

  My question is why does the FDDI port go to standby and not one of the port
three connections. And also why are we seeing none of the ports go to standby
after we reconnect the port three connections to the thinwire lan.

  I am wondering if there is some in-compatability between the 900MX and the
900EF devices causing this or do I have a broken bridge, or is spanning tree
messed up.


  Brad Lewis USCSC

T.R	Title	User	Personal Name	Date	Lines
2099.1		NETCAD::ANIL		`Wed Mar 15 1995 11:32`	11
	The reason why the FDDI rather than the thinwire goes into backup might be because the root bridge is connected via the thinwire. This would make the thinwire the inlink (link closer to the root) for both bridges, thus forcing the FDDI into backup. I don't understand why the FDDI doesn't go back to backup state after disconnecting and reconnecting port 3. There is no incompatibility in STP between the MX and the EF, they're basically the same device. Is the module-OK LED blinking on either of the two? Anil
2099.2	Change port cost.	CGOS01::DMARLOWE	Wow! Reality, what a concept!	`Wed Mar 15 1995 14:19`	5
	I ran into similar problems except thru front panel AUI's. I solved the problem by changing the FDDI port cost from 4 to 2 on both switches. Works like a hot damn now. dave