Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!cornell!batcomputer!sun.soe.clarkson.edu!abstine From: abstine@sun.soe.clarkson.edu (Arthur Stine) Newsgroups: comp.dcom.lans Subject: Re: Performance problems with a DESPR Message-ID: <2749@sun.soe.clarkson.edu> Date: 28 Mar 89 14:12:21 GMT References: Sender: abstine@sun.soe.clarkson.edu Lines: 36 From article , by eriks@yunexus.yorku.ca (Eriks Rugelis): >>I have the following configuration set up, which seems to be 'legal' >>according to DEC's Network and Communications Buyer's Guide. > 'seems to be legal'?... I haven't seen a recent copy of the N&CBG but > I would be surprised if DEC allowed you to plug a DESPR into a DELNI > > why? well because the DESPR is a repeater and a DEC supplied DELNI operating > in 'local' mode generates heartbeat and repeaters cannot tolerate heartbeat; > a repeater operating in the presence of heartbeat will see excessive collisions > and will have the poor performance behaviour that you describe > > solution? replace the DELNI with a similar box not made by DEC that allows > you to select/deselect heartbeat (i.e. I use Cabletron's MT-800's)... > I have installed and running many instances of repeaters plugged into > multi-port transceivers so it is demonstrably workable > > Eriks Almost...according to the 'book', you can attach up to eight DEMPR/DESPR to a DELNI provided: 1) the standard ethernet segment the DELNI is attached to is < 300 meters and it is attached using a H4000-BA/H4005 (standard transceiver w/o heartbeat) 2) if it is standalone, put the DELNI in global mode and put a loopback connector on the network port. This will eliminate the heartbeat signal, as the DELNI will take heartbeat from whatever it is attached to when it is in global mode. Note that the Cabletron MT800 allows you to turn on/off heartbeat in a much easier way (a switch), but it still does not allow you to do it on a port by port basis. art stine sr network engineer clarkson u