Specifications

Configuring IP Multicast Multilayer Switching
Configuring and Monitoring IP Multicast MLS
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External Router Guidelines
Follow these guidelines when using an external router:
• The connection to the external router must be over a single ISL or 802.1Q trunk link with
subinterfaces (using appropriate encapsulation type) configured.
• A single external router can serve as the MMLS-RP for multiple switches, provided each switch
connects to the router through a separate ISL or 802.1Q trunk link.
• If the switch connects to a single router through multiple trunk links, IP multicast MLS is supported
on one of the links only. You must disable IP multicast MLS on the redundant links using the no mls
rp ip multicast interface configuration command.
• You can connect end hosts (source or multicast destination devices) through any media (Ethernet,
Fast Ethernet, ATM, and FDDI), but the connection between external routers and the switch must
be through Fast Ethernet or Gigabit Ethernet interfaces.
Access List Restrictions and Guidelines
The following restrictions apply when using access lists on interfaces participating in IP multicast MLS:
• All standard access lists are supported on any interface. The flow is multilayer switched on all
interfaces on which the traffic for the flow is allowed by the access list.
• Layer 4 port-based extended IP input access lists are not supported. For interfaces with these access
lists applied, no flows are multilayer switched.
• Extended access lists on the RPF interface that specify conditions other than Layer 3 source, Layer 3
destination, and ip protocol are not multilayer switched.
For example, if the following input access list is applied to the RPF interface for a group of flows,
no flows will be multilayer switched even though the second entry permits all IP traffic (because the
protocol specified in the first entry is not ip):
Router(config)# access-list 101 permit udp any any
Router(config)# access-list 101 permit ip any any
If the following input access list is applied to the RPF interface for a group of flows, all flows except
the {s1, g1} flow are multilayer switched (because the protocol specified in the entry for {s1, g1}
is not ip):
Router(config)# access-list 101 permit udp s1 g1
Router(config)# access-list 101 permit ip any any
Configuring and Monitoring IP Multicast MLS
To configure your Cisco router for IP multicast MLS, perform the tasks described in the following
sections. The first two sections contain required tasks; the remaining tasks are optional. To ensure a
successful multicast MLS configuration, you must also configure the Catalyst switches in your network.
For a full description, refer to the Catalyst 5000 Series Multilayer Switching User Guide.
• Enabling IP Multicast Routing (Required)
• Enabling IP PIM (Required)
• Enabling IP Multicast MLS (Optional, this is a required task if you disabled it.)
• Specifying a Management Interface (Optional)