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ATM Switch Router Software Configuration Guide
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Chapter25 Configuring ATM Router Module Interfaces
Configuring LECs on ATM Router Module Interfaces (Catalyst 8540 MSR)

Default ATM Router Module Interface Configuration Without Autoconfiguration

If ILMI is disabled or if the connecting end node does not support ILMI, the following defaults are
assigned to all ATM router module interfaces:
ATM interface type = UNI
UNI version = 3.0
Maximum VCI bits = 11
MTU size = 1500 bytes
ATM interface side = network
ATM UNI type = private
Note Only Catalyst 8540MSR enhanced ATM router module interfaces support IP unicast and IP multicast
fragmentation. For IP unicast fragmentation, the packet must ingress on an enh anced ATM router module
interface and egress on any interface. For IP multicast fragmentation, IP multicast data packets greater
than 1500 bytes are fragmented to 1500 bytes on the ingress enhan ced ATM router module interface
before being switched to other members in the multicast group. All the members in the multicast group
must have an MTU equal to or greater than 1500 bytes.
Configuring LECs on ATM Router Module Interfaces
(Catalyst 8540 MSR)
The procedures for configuring LANE clients (LECs) on the ATM router module or enhanced ATM
router module are the same as for the configuration of LECs on the ro ute processor, with one exception:
To specify an ATM router module interface, rather than the route processor interface, use the interface
atm card/subcard/port command. On the route processor, you would use the interface atm 0 command.
Note To route traffic between an emulated LAN and a Fast Ethernet (FE) or Gigabit Ethernet (GE) interface,
you must configure the LEC on either the ATM router module or enhanced ATM router module interface
rather than a route processor interface.
Note With the enhanced ATM router module, both LEC and RFC 1483 PVCs configuration is supported on
the same enhanced ATM router module interface. For example, LEC and RFC 1483 PVCs configuration
is allowed on different subinterfaces of the same main interface of the enhanced ATM router module
port.
Configuring both LEC and RFC 1483 PVCs on the same interface was not supported on the earlier
version of the ATM router module. Either LEC or RFC 1483 PVCs could be configured on the
subinterfaces of an ATM router module main interface. For both LECs and RFC 1483 PVCs to operate
on the same ATM router module, you must configure LECs on the subinterfaces of one main interface
and RFC 1483 PVCs on the subinterfaces of the other main interface.