🚀 go-pugleaf

In article <733@abic.UUCP> dlb@abic.UUCP (David Bernard) writes:
>    I am interested in a gateway/bridge product that will provide   
>    a link between IEEE 802.3 & 802.4 networks.
> 
>    Does anyone have knowledge of such a product?  I understand that
>    Bridge Communications and DEC have an offering along this line.
> ...
>                Dave Bernard
>                Allen-Bradley Co.
>                decvax!abic!dlb 

Bridges get involved at the network layer.  IEEE 802.3 & 802.4 only
specify up through the data link layer.  What bridge you need depends
on what network layer protocols you need.  For example, Ungermann-Bass
provides networks based on a variety of different protocols.  Which
bridge software you get depends on which network protocols you're using.
Like Ungermann-Bass's, Bridge's and DEC's bridges will only work on
networks that use their protocols.  Fortunately, we've all started basing
our products on standard protocols, so depending on your system,
vendor A's network interface units may communicate using vendor B's
bridges.

Buffered repeaters do exist that don't know anything about layers higher
than the data link layer.  That may be what you want.  Ungermann-Bass
offers those, as does a company by the name of Veralink, if I remember
right.  For information on Ungermann-Bass's stuff you can contact me.
I don't have an address or telephone number for Veralink, sorry.

-- Skip Addison
   {lll-crg, decwrl, ihnp4}!amdcad!cae780!ubvax!skip
   Ungermann-Bass, Inc
   (408) 496-0111

Interactive Systems in Ann Arbor, Michigan has announced an 802.3 to 802.4
bridge or gateway that runs either ISO or TCP/IP protocols (I believe).  They
used to be owned by 3M and are now owned by Allen-Bradley.  They can be
reached at:

	3920 Varsity Drive
	Ann Arbor, MI 48104
	(313) 973-1500

The product is called a LAN/II Network Bridge Unit.  I have no experience
with the product.

George Pavel					ARPANET/MILNET:	gp@lll-crg
Lawrence Livermore National Laboratory		UUCP: {ihnp4,seismo}!lll-crg!gp
P.O. Box 808  L-61
Livermore, CA 94550
(415)422-4262

>    I am interested in a gateway/bridge product that will provide   
>    a link between IEEE 802.3 & 802.4 networks.

Charles River Data Systems demonstrated such a system at AUTOFACT'85 in
Detroit.  It was a gateway between MAP (802.4) and TOP (802.3).  I don't
have any direct experience with the product, but I saw it work at the show.

-----------------------------------------------------
Frederic W. Brehm       (ihnp4!princeton!siemens!fwb)
Siemens Research and Technology Laboratories
105 College Road East
Princeton, NJ 08540
(609) 734-3336

In article <440@ubvax.UUCP>, skip@ubvax.UUCP (Skip Addison Jr) writes:
> ... Which
> bridge software you get depends on which network protocols you're using.
> Like Ungermann-Bass's, Bridge's and DEC's bridges will only work on
> networks that use their protocols.

DEC's bridge is protocol independant. we have one here that is running
with DECnet and TCP/IP now and we will move it next week to a place
that also uses XNS. no problems seen so far.

	scott bradner
	harvard university
	sob@harvard.{uucp,arpa,csnet,harvard.edu}
	sob@harvunxt.bitnet

In article <440@ubvax.UUCP> skip@ubvax.UUCP (Skip Addison Jr) writes:
>Bridges get involved at the network layer.  IEEE 802.3 & 802.4 only
>specify up through the data link layer.  What bridge you need depends
>on what network layer protocols you need.

Perhaps we're working with different definitions, but according to
my understanding of terms like "bridge", this is just plain wrong.

You're saying that 802.3 only goes up through the data link layer,
and at least one OSI person agrees with you, calling the 48 bit
Ethernet address a way of handling a "multipoint data link layer"
rather than a network layer.  Personally, I think if it looks like
a duck and quacks like a duck, it's a duck (or a good emulation),
even if it didn't hatch from an official duck egg.  I think Ethernet
and 802.3 support a network layer, and the IP or CLNS or IDP layer
above it is a sublayer of the same network layer above Ethernet.

But you say that bridges work above what 802.2 provides, which seems
to me that you're talking about the IP or CLNS et al layer.  To me,
this is not a bridge, it's a "gateway" or "packet router".

In my book, an Ethernet bridge operates at the Ethernet (802.2) layer.
It's much like a repeater with a buffer and some smarts about where to
route Ethernet level packets (based on its knowledge about which segment
the destination address is on.)  These bridges can connect various 802.2
networks together, such as 802.3 Ethernet to 802.4, and even hook similar
or different networks together with random virtual or physical circuits.
Such bridges are, as one of their features, totally transparent to whatever
protocols you may be running at the higher levels.

Gateways work at the same level as their peers on other nodes, so the
end to end protocols matter.  Bridges do not have peers on the other
side of the net, so they appear to not be there on the other end.
Gateways operate pretty much at one level, and are built into the
network architecture.  Bridges understand any lower levels they are
working with, so you can think of them as working at the next higher
level.  But this is still below the real next higher level; an Ethernet
bridge in effect works in a layer above Ethernet but below IP.

Incidently, is there a bridge between Ethernet (or 802.3) and Starlan
available or in the works?  Sure might be handy for cabling to run an
Ethernet backbone trunk with Starlan into the offices, or on the other
hand, to use Starlan for the building wiring (to reuse existing wiring)
but to plug in boxes with an Ethernet interface.  I'm thinking of something
inexpensive - almost like an adaptor, not a big expensive general purpose
bridge.

	Mark

> Bridges get involved at the network layer.  IEEE 802.3 & 802.4 only

Sorry, "bridges" as that word is used by DEC, the INTERNET world
and other significant portions of the free world does NOT deal
with the network layer.  Only through the datalink layer.

> specify up through the data link layer.  What bridge you need depends
> on what network layer protocols you need.  For example, Ungermann-Bass
> provides networks based on a variety of different protocols.  Which
> bridge software you get depends on which network protocols you're using.
> Like Ungermann-Bass's, Bridge's and DEC's bridges will only work on
> networks that use their protocols.  Fortunately, we've all started basing

Even a quick look at DEC's marketing literature, let alone a technical
understanging show's that DEC's bridges are independant of protocol.

Your posting is both wrong an a little commercial...


-- 
marty schoffstall
schoff%rpics.csnet@csnet-relay	ARPA
schoff@rpics			CSNET
seismo!rpics!schoff		UUCP
martin_schoffstall@TROY.NY.USA.NA.EARTH.SOL	UNIVERSENET

RPI
Computer Science Department
Troy, NY  12180
(518) 271-2654

In article <1@rpics.uucp> schoff@rpics.uucp (Martin Schoffstall) writes:
>> Bridges get involved at the network layer.  IEEE 802.3 & 802.4 only
>
>Sorry, "bridges" as that word is used by DEC, the INTERNET world
>and other significant portions of the free world does NOT deal
>with the network layer.  Only through the datalink layer.
> ...
>-- 
>marty schoffstall
>schoff%rpics.csnet@csnet-relay	ARPA
>schoff@rpics			CSNET
>seismo!rpics!schoff		UUCP
>martin_schoffstall@TROY.NY.USA.NA.EARTH.SOL	UNIVERSENET
>
>RPI
>Computer Science Department
>Troy, NY  12180
>(518) 271-2654

Since I posted the last message, some more followups have come into our
machine.  

The people reading this group include an especially high level of TCP/IP
users.  I wonder whether the networking terminology breaks cleanly into two or
three camps one of which is the ARPA usage.  I am sure that my usage does not 
reflect just Ungermann-Bass's terminology but those of some other 'significant 
portions of the free world.'  I'm curious as to what other sets of terminology 
are widely used.  My intent is not to say that I'm right or you're right or 
engage in any battles.

Incidentally, I posted an article earlier today with a full set of definitions
the way I use them.  My LAN books with definitions from other people are at
home.  If it seems worth-while (if I need them to defend my terminology :-)
I'll post some things from there.

-- Skip Addison
   {lll-crg, decwrl, ihnp4}!amdcad!cae780!ubvax!skip

In article <1828@cbosgd.UUCP> mark@cbosgd.UUCP writes:
>Incidently, is there a bridge between Ethernet (or 802.3) and Starlan
>available or in the works?  Sure might be handy for cabling to run an
>Ethernet backbone trunk with Starlan into the offices, or on the other
>hand, to use Starlan for the building wiring (to reuse existing wiring)
>but to plug in boxes with an Ethernet interface.  I'm thinking of something
>inexpensive - almost like an adaptor, not a big expensive general purpose
>bridge.

The answer to this question would be very interesting. However, does
Starlan really exist yet? Neither net.lan nor net.dcom has much, if any,
mention of Starlan. What I want to know is where can I get it, and how
much will it cost.