[Cu-wireless] Re: Cu-wireless digest, Vol 1 #138 - 3 msgs

The Morenz Family mmorenz at ameritech.net
Tue May 28 12:33:27 CDT 2002

Hi David, et. al.

Replies inline...this is off the top of my head, so bear with any 
silly mistakes. I'm rushing out the door:

>Message: 2
>Date: Sun, 26 May 2002 13:11:32 -0500
>From: David Young <dyoung at ojctech.com>
>To: cu-wireless at lists.groogroo.com
>Subject: Re: [Cu-wireless] Re: Cu-wireless digest, Vol 1 #134 - 3 msgs
>Reply-To: dyoung at pobox.com
>Hi Mark,
>Must an NBMA network have a D.R.? If we set every router's priority for
>election as D.R. to 0, do we get broken routing or working routing w/o
>any D.R.'s ?

In a multiple access scenario  ("the MA in NBMA"), Designated Router 
elections are necessary since DR's are the only routers to forward 
link-state updates. Like any election, it can be rigged. But when you 
set them *all* to "0" I believe you are essentially preventing DR 
election and breaking the routing. I'd have to defer to Jon or 
Stephan on this.

>Suppose we enumerate the hosts on a pod (there are at most 16 or 32),
>and we make each a point-to-point link. Will that work?

Yes or no, depending on the topology. Once you do this, you must have 
a series of point-to-points (completely hierarchical) or 
point-to-multipoint (extended star) and then DR elections will not 
take place. Since you are committed to at least a partial-mesh in 
your design specs, I think pmp is the only option (with the 
accompanying drawbacks), as I stated earlier.

>Suppose, too, we enumerate the hosts on an uplink network and make each
>a point-to-point link?
>It is more clear all the time that OSPF is not the routing protocol we
>want to use. I think that the protocol we do want to use, we will have
>to program ourselves to operate in Zebra. It is probably DSDV, AODV,
>or one of the other new-fangled routing protocols for ad hoc networks.

I wasn't aware of those until you mentioned them. From what I'm 
reading of them, they're all still being tested. We would truly be on 
the edge of the envelope. Good way to get a grant, I'd say...

I may not make the meeting tonight, so I can't commit to being your 
lecturer, sorry. There are certainly some others who can comment on 
OSPF more expertly than I can.

Does anyone know the answer to my earlier question...can you have 
more than one subnet/logical network on the same channel in the same 
airspace? That would be a prerequisite, it seems to me, to do the PMP 
design that we're thinking of.

Take Care!


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