CONFIGURATION AND INSTALLATION
Page 2-7
Even though RMIMs can place Ethernet traffic on the bus that
normally handles FDDI traffic, FDDI MIMs can still reside in the
same hub with RMIMs. RMIMs determine whether or not the MIM
that resides in the next higher numbered MMAC slot is an Ethernet
MIM. If the next MIM is not an Ethernet MIM, the RMIM activates
relays that, in effect, terminate the B and C buses. To eliminate
potential problems, we recommend installing the RMIMs in lower
numbered slots and the FDDI MIMs in higher numbered slots.
For example, assume that we have an MMAC-5FNB with the
following configuration:
Slot 1 - EMME
Slot 2 - TPRMIM-36
Slot 3 - FDCMIM-04
Slot 4 - FDCMIM-08
After turning on the MMAC, the TPRMIM checks the MIM in slot 3.
When it determines that slot 3 does not hold an Ethernet MIM, it
activates the relays that terminate the Ethernet section of the B and C
buses. This isolates the FDCMIMs from the rest of the MIMs in the
hub. This example uses the TPRMIM, but the same is true if you use
any of the other RMIMs as well.
For a more thorough description of the RMIMs and how they use the
MMAC buses, see your RMIM documentation.
2.3.4
TRMM and Token Ring MIMs with FDCMIMs
Token Ring and FDDI traffic on an MMAC bus follow distinct
pathways. As long as your Token Ring MIMs reside in adjacent lower
numbered slots, and the FDDI MIMs reside in adjacent higher
numbered slots, the two networks can peacefully share an MMAC.
For example, if you have an MMAC-5FNB with a TRMM (Token Ring
Management Module) in slot 1, and TRMIM-12s in slots 2 and 3, you
can put an FDCMIM in slot 4. The FDCMIM inter-connects any
workstations that attach to its master ports and functions as a stand-
alone network. The FDCMIM coexists, but does not communicate,
with the adjacent Token Ring network.
