System information

72 IBM and Cisco LAN Switching: Interoperability and Migration Guide
IPX is not supported by the Catalyst MPOA client at this point in time.
Therefore IPX traffic must be routed by an ATM router. Non-routable traffic
obviously must be bridged. As mentioned, this is readily handled by the MSS
or for example, a Cisco 7200.
4.1.3 Future phases
As mentioned earlier in this redbook, it seems very probable that Ethernet will
be the standard interface for all digitized transports in the not-too-distant
future. ATM will still play a significant role in the wide-area network, but much
of the equipment on customer premises will likely present the user with an
Ethernet interface.
For this reason, the users of ATM backbones may want to plan for the removal
of the ATM switches from their LAN. In some cases, this may be
accomplished quickly, while in other cases it would not be possible to do so in
the foreseeable future.
Cost savings on operations or lack of skills to maintain the ATM backbone
may make it desirable to remove the ATM switch and use a plain translational
bridge or Cisco ISL encapsulation on Cisco routers and switches, depending
on requirements.
If the ATM backbone is used for legacy telephony or circuit-switched video
conferencing, it is probably advantageous to keep it until the time when all the
attached equipment has been depreciated and replaced by newer equipment
with an Ethernet interface.
Parallel bridges in an Ethernet environment can be used to provide
redundancy. If more than one MSS or Cisco router provide translational
bridging, the spanning tree protocol (STP) must be invoked to avoid loops
or duplication of frames. This puts a limit on the amount of bridged traffic
that can flow between the Ethernet and the token-ring LANs. The limit is
determined by the bridging capacity of an MSS or a Cisco router. This is
normally not a problem because non-routable traffic will usually have other
constraints. Employing the intelligent broadcast reduction function of the
MSS can also reduce the amount of traffic to be bridged.
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