Cabletron Systems Cabletron BRIM-F6, Networking Manual

Page: 80 / 132

Ethernet
6-18 Ethernet Workgroup Design
Design Example
For an example of remote office workgroup configuration, we will build upon the
previous small office example. Let us assume that there has been no growth of the
small office network, but the pottery distributor has been purchased by a larger,
nationwide chain of distributors. The facility itself will not be changing
appreciably, but the facility will need a Wide Area Network connection to the
regional headquarters in a neighboring state. The regional office makes
connections to the remote distributors with 56K WAN links in order to keep
running, constantly-updated inventory and accounting records.
When comparing the available methods of connecting to the WAN, the Network
Designer determines that a Cabletron Systems BRIM, the BRIM-W6, is capable of
handling 56K WAN traffic. The networking hardware is still handling network
traffic in the facility properly, so there is no need to upgrade the network itself,
but the SEHI-24 that is the base of the stack will not support a BRIM.
Looking back at the selection chart, the Network Designer notices that the
MicroMMAC-24E, another device that can act as a stackable base, supports one
BRIM connection. In order to be certain that the network that is being considered
will work, the Network Designer consults the table of BRIM interoperability and
determines that the BRIM-W6 will, in fact, work properly in the
MicroMMAC-24E.
The new design requires the replacement of the SEHI-24 with a MicroMMAC-24E
containing a BRIM-W6. The stackable hub previously controlled by the SEHI-24
will remain, and will be connected to the MicroMMAC-24E through the HubStack
Interconnect Cables.
The SEHI-24 can then be placed in storage, ready to be swapped in should there
be a problem with the MicroMMAC that requires it be sent back to Cabletron
Systems for service. This arrangement of on-site spares can greatly reduce the
amount of downtime, or non-operation, that a network experiences.
The BRIM-W6 in the MicroMMAC-24E requires further configuration to work
with the 56K link. The BRIM-W6, in order to provide the greatest flexibility to
consumers, uses specialized PIMs for connection to different WAN types. These
Wide Area Network Port Interface Modules, or WPIMs, are listed in the PIMs
table, Table 4-1. Examining the table to see which WPIM matches the needs of the
facility, the Network Designer chooses the WPIM-DDS. The resulting network
now looks like Figure 6-6.
NOTE
Intelligent stackable devices cannot be placed in a stack with
other intelligent stackable devices. The intelligent devices do
not have IN ports for HubStack Interconnect cables.