| Title: | FDDI - The Next Generation |
| Moderator: | NETCAD::STEFANI |
| Created: | Thu Apr 27 1989 |
| Last Modified: | Thu Jun 05 1997 |
| Last Successful Update: | Fri Jun 06 1997 |
| Number of topics: | 2259 |
| Total number of notes: | 8590 |
Most of my FDDI experience has been with using FDDI as a backbone
transport, not as connecting systems directly yo it. I am just looking
for confirmation of my thoughts on the following configuration:
1. Connected to the FDDI ring is a Server system.
2. Connected to an attached Ethernet is a client system using Ethernet
V2 packet format.
3. Connected to another attached Ethernet is another client system
which is using 802.3 packet format.
My question is concerning the server receiving receiving packets from
ethernet clients which are sending these packets in two different
formats. Does the Server have to manually be configured to have the
awareness of the packet format of each system that communicates which
it?
Without putting down all of my thoughts on this, I believe the answer
here is no, but I am not sure and would like some confirmation before
talking again with this customer.
The customer currently has some ethernets with Servers/Clients running
in Ethernet V2 for mat and some ethernts with Servers/Clients running
in 802.3 format. They wish to begin migrating all their servers to the
FDDI backbone. They also do not want to have to modify half of the
clients to support the "other" protocol format.
Thanks,
Mark
| T.R | Title | User | Personal Name | Date | Lines |
|---|---|---|---|---|---|
| 953.1 | Half the answer | JUMP4::JOY | Perception is reality | Fri May 14 1993 17:50 | 18 |
Mark,
If memory serves me correctly, the DECbridge translates all packets
to 802 SNAP format or in other words, does a 2 step translation on
Ethernet V2.0 packets (Ethernet V2.0 -> 802.3 -> FDDI) and 1 step for
802.3 format (802.3 -> FDDI). Somewhere in the FDDI frame, there is an
indicator as to which format it was on the Ethernet side (type field
imbedded somewhere in the data I believe). This was so it could get
translated back into the correct format if it was destined for another
Ethernet and just using the FDDI as a transport between Ethernets. So,
in your case, when the server receives the packet, it will be
translated just fine, although I'm not sure if the device drivers have
any code to look into the packet to see what kind of frame it WAS and
then send frames back in the proper format. I'm stuck on that part.
Hey, I got you half the answer at least!
Deb
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| 953.2 | KONING::KONING | Paul Koning, A-13683 | Fri May 14 1993 19:23 | 17 | |
Unless the bridge is specifically set up differently (e.g., for
Appletalk) Ethernet V2 packets are translated to SNAP frames with
Protocol ID of 00-00-00-xx-yy where xx-yy was the original Ethernet
protocol type.
What happens at the FDDI server end depends on the server. If it's a
VMS system, the device driver will essentially pretend to be a bridge:
if it sees a packet of the form I mentioned, it tells the application
that it saw an Ethernet packet. So applications that work with
Ethernet and 802.3 work unchanged. Whatever configuration, if any, was
needed on the orange hose applies when they run on FDDI.
I don't remember if the Ultrix driver does the same thing.
What sort of server, and what protocol on it, are you talking about?
paul
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| 953.3 | Thanks | DPDMAI::DAVIES | Mark, SCA Area Network Consultant | Sun May 16 1993 23:46 | 7 |
The systems involved are running Novell Netware using IPX. The network
equipment is from Digital (DB620s and assorted Ethernet components).
Thanks for help.
Mark
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| 953.4 | KONING::KONING | Paul Koning, A-13683 | Mon May 17 1993 13:38 | 6 | |
I thought you might say that. Try to avoid "raw 802.3" mode when using IPX. If I remember right, suitably recent versions of the bridge firmware can handle it, but it's best to stay away from it. (A better name for that mode would be "Novell ignorant about 802 standards mode".) paul | |||||