🚀 go-pugleaf

In article <1992Oct29.215308.15464@msuinfo.cl.msu.edu>, craven@egr.msu.edu (Dean Craven) writes:
> Is there any protocol specification or vendor specific implementation
> for tunneling source routed 802.5 frames through a FDDI or Ethernet
> LAN?  That is, can two bridges, each attached to a 802.5 LAN, bridge
> source routed frames across a FDDI/Ethernet LAN to/from 802.5 end
> stations which only know how to source route?
> 
> Or, is this problem only ever solved by network layer routing?
> 
There is no need to tunnel at all. A source routing bridge connected
between a Token Ring and an FDDI or Ethernet will talk correctly to
another source routing bridge connected to the same LAN. That is, no
special measures need to be taken to use an Ethernet or an FDDI as a
backbone for source routed token rings.

It is important that there be no transparent bridges in the path between
the source routing bridges. Transparent Bridges will not pass source
routed frames.

Of course, there will be no connectivity to devices connected to the backbone.
Neither Ethernet nor FDDI devices support source routing. Let's just
hope that it won't cause them to crash--The problem area is when
someone sends a frame to a multicast (or broadcast) with source routing
enabled. The receiving Ethernet or FDDI station will see a source 
address with the Routing Information Indicator set to one. This looks
like a multicast source address, which is outlawed in Ethernet.

I don't believe this is a problem in practice. It may cause a counter
to be bumped, but should not disrupt proper operation.


-- 
Rich Seifert                    Networks and Communications Consulting
seifert@netcom.com              (408) 996-0922
                                (408) 996-2860 FAX
"... specialists in Local Area Networks and Data Communications systems"