Cisco ATM and Layer 3 Switch Router OL-1911-05 User Manual

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ATM and Layer 3 Switch Router Software Configuration Guide


Chapter 24

Configuring ATM Router Module Interfaces

Hardware and Software Restrictions of the ATM Router Module

Catalyst 8540 MSR ATM Router Module Software Restrictions

The following software restrictions apply to the Catalyst 8540 MSR ATM router module:

Use tag switching functionality with caution. Do not distribute routes learned through tag switching
to FE or GE, or vice versa. Otherwise, you might have unreachable route destinations.

The ATM router module does not initialize if it replaces an ATM port adapter or interface module
when hierarchical VP tunnels are globally enabled. Reboot the switch to initialize the ATM router

ATM Director does not support any PVC commands.

Only LANE clients or RFC 1483, not both, can be configured on an ATM router module interface.

RFC 1483 on the ATM router module supports only AAL5 SNAP encapsulation.

Even though each ATM router module interface supports a maximum of 2048 VCs, only
1400 to 1500 external VCs can be configured. Internal VCs use up the rest.

IP multicast is only supported over 1483 LLC/SNAP encapsulated PVCs.

You can have a maximum of 64 LECs per chassis.

Do not install an ATM router module in a slot pair where hierarchical VP tunnels are configured.
Slot pairs 0 and 1, 2 and 3, 9 and 10, and 11 and 12 use the same switching modules for scheduling.
For example, do not install an ATM router module in slot 10 when hierarchical VP tunnels are
configured on slot 9. For more information on hierarchical VP tunneling restrictions, see

Chapter 6,

“Configuring Virtual Connections.”

Token Ring LANE is not supported.

The Catalyst 8540 MSR ATM router modules do not support the following features:

Tag-edged router functionality

Fast Simple Server Redundancy Protocol (SSRP)

Bridging for multiplexing device encapsulation

PIM IP multipoint signalling


PIM over ATM multipoint signalling

Translation from IP QoS to ATM QoS


PVC management using ILMI

Access lists for ATM to ATM routing

Half-bridge devices

RFC 1483 MUX encapsulation

IP multicast over RFC 1483 SVCs

ACLs for IP, and standard ACLs for IPX

IP fragmentation.

IP 6-path load balancing.