In most Catalyst equipment (such as the Catalyst 5000), both MPOA and LANE use MAC addresses from the chassis or Supervisor to automatically generate ATM NSAP addresses. For a detailed discussion of how NSAP addresses are created, refer to Chapter 9. When designing an ATM network, keep the following address-related points in mind:
• Devices with active backplanes such as the Catalyst 5500s use MAC addresses pulled from the backplane itself. Changing the chassis of one of these devices therefore changes the automatically-generated NSAP addresses.
• Devices with passive backplanes such as the Catalyst 5000 use MAC addresses from the Supervisor. Therefore, changing a Catalyst 5000 Supervisor module changes the pool of addresses used for automatically generating NSAP addresses.
• In both cases, 16 MAC addresses are assigned to each slot. Therefore, simply moving a LANE module to a different slot alters the automatically generated NSAP addresses.
• Because of these concerns, many organizations prefer to use hard-coded NSAP addresses. For more information, see the section "Using Hard-Coded Addresses" in Chapter 9.
Consider using hard-coded NSAP addresses in a large LANE network.
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