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Date:      Thu, 29 Aug 1996 16:50:17 -0700
From:      Julian Elischer <julian@whistle.com>
To:        grefen@carpe.net
Cc:        freebsd-atm@freebsd.org
Subject:   Re: Virtual Circuit support (fwd)
Message-ID:  <32262CB9.2781E494@whistle.com>
References:  <m0utDG3-00001ZC@ernie.kts.org> <4813.840656512@hex.grefen.carpe.net> <321B962C.59E2B600@whistle.com> <7753.840700743@hex.grefen.carpe.net> <321CEE16.31DFF4F5@whistle.com> <2374.841351869@hex.grefen.carpe.net>

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Stefan Grefen wrote:
> 
> In message <321CEE16.31DFF4F5@whistle.com>  you wrote:
> > > Can I have a look at it?
> > >
> > > [...]
> >
> > hopefully the attached shar file comes through ok..
> > if_wfra.c is a proprietary frame relay card driver,
> > but it interfaces to the vc code and is an example of how to use it..
> 
> I got it (sorry my day jobs get the nights too at the moment).

so do mine.. I didn't get home at all last night..

the vc stuff is shelved for 2 or 3 weeks while we go into beta
with teh (freebsd based) product

> 
> It is mostly what I want todo. What bugs me is that it doesn't fit into
> the BSD design. Stacking visible interfaces that way, doesn't 
> 'feel' right.

true, but maybe we can put the ones we want to be INvisible on a
separate list.. the thing is that the "interface" structure holds all
the information we need.
the routing structures don't nor do the ifaddr structs..

it turns out that interfaces are now very dynamic..
the only thing I have against using them is that they clutter
up the  netstat output (or ifconfig). however having them visible
does allow them to be reached for 'tacking' modules (ala streams )
onto them.




> 
> My goal is to make an implementation that fits in the architecture.
> I looked further around and think if I would merge your code with the
> routing table tricks in netcitt, we would get the same functionality without
> the stacked interface. 
well Something has to be stacked.. and  why make aup a new
structure to do it..?  I notice BTW that teh RFC1490 code is really 
s sub/super set of the LLC code in if_ethersubr.c..
I guess that requires some rationalisation.

> I would attach the information for the vc's and the
> encapsulation to routing structures (I would use the llinfo pointer).
I tried that but how do you stack them?


> 
> You would add routes to SAP's to the routing tables and the information
> about the encapsulation and any necessary addressing is embedded in the SAP.
yeeessss,  
I tried to use Llinfo fields and adding extra ifaddrs on the
interfaces..
but it became a mess because teh scope fo teh information is all wrong..
the interfaces may need to have many VCs all on differnt 
logical networks and all
possibly using different encapsulation..
while this looks at the start like a use for llinfo
fields, in the end it became hellishly complicated..
especially when:

a single fram relay link might have 3 links on one network (sharing a 
single local address and several on totally different addresses.

> eg.
>         route add yy.xx.dd.00 -frame E:some-name
>         route add -frame  some-name -ifp frame0
> 
> 
> for isdn
>         route add -inet yy.xx.dd.00 -isdn R:D.6192920404
>         route add -isdn D.6192920404 -ifa D.6131998566

for this, route has to know in advance about every type of
encapsulation or whatever.. I would like to have things attached by
ascii names if possible :)


> 
> Assuming that E stands for Etherframes and R for Raw.
> (The D stand s for isdn data service)
> 
> The parsing of the encapsulation would be hidden in the library.

I'd like to have each module do its own parsing..
or we'll spend FOREVER editing route(1) and friends

I'm really just skimming this for now..
so that you get an answer
I'll think about it more..
p.s. I cc'd it to the atm group..
they're about to need the same stuff too, and I think rfc1490
applies to atm as well.

> 
> >
> >
> >
> > julian
> 
> Stefan
> --
> Stefan Grefen                            Am Grossberg 16, 55130 Mainz, Germany
> grefen@carpe.net                         +49 6131 998566   Fax:+49 6131 998568
> Living on Earth may be expensive, but it includes an annual free trip
> around the Sun.



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