Specifications

Configuring IPX Multilayer Switching
Restrictions
2
• IPX MLS must be configured on the switch. For more information refer to the Catalyst 5000
Software Configuration Guide, Release 5.1 and the Catalyst 5000 Command Reference, Release 5.1.
IPX MLS must be enabled on the router. The minimal configuration steps are described in the section
“IPX MLS Configuration Tasks.” For more details on configuring IPX routing, refer to the Cisco IOS
AppleTalk and Novell IPX Configuration Guide.
Restrictions
This section describes restrictions that apply to configuring IPX MLS on the router.
General Configuration Guidelines
Be aware of the following restrictions:
• You must configure the Catalyst 5000 series switch for IPX MLS to work.
• When you enable IPX MLS, the RSM or externally attached router continues to handle all non-IPX
protocols, while offloading the switching of IPX packets to the MLS-SE.
• Do not confuse IPX MLS with NetFlow switching supported by Cisco routers. IPX MLS requires
both the RSM or directly attached external router and the MLS-SE, but not NetFlow switching on
the RSM or directly attached external router. Any switching path on the RSM or directly attached
external router will function (process, fast, optimum, and so on).
External Router Guidelines
When using an external router, use the following guidelines:
• Use one directly attached external router per switch to ensure that the MLS-SE caches the
appropriate flow information from both sides of the routed flow.
• Use Cisco high-end routers (Cisco 4500, 4700, 7200, and 7500 series) for IPX MLS when they are
externally attached to the switch. Make the attachment with multiple Ethernet connections (one per
subnet) or by using Fast or Gigabit Ethernet with Inter-Switch Link (ISL) or IEEE 802.1Q
encapsulation.
• Connect end hosts through any media (Ethernet, Fast Ethernet, ATM, and FDDI), but connect the
external router and the switch only through standard 10/100 Ethernet interfaces, ISL, or IEEE
802.1Q links.
Access List Restrictions
The following restrictions apply when you use access lists on interfaces that participate in IPX MLS:
• Input access lists—Router interfaces with input access lists cannot participate in IPX MLS. If you
configure an input access list on an interface, no packets inbound or outbound for that interface are
Layer 3 switched, even if the flow is not filtered by the access list. Existing flows for that interface
are purged, and no new flows are cached.