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Cisco 7600 Series Router Cisco IOS Software Configuration Guide—12.1E
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Chapter 18 Configuring IP Multicast Layer 3 Switching
IP Multicast Layer 3 Switching Configuration Guidelines and Restrictions
IP Multicast Layer 3 Switching Configuration Guidelines and
Restrictions
These sections describe IP Multicast Layer 3 switching configuration restrictions:
• PFC2 with MSCF2, page 18-8
• PFC1 with MSFC or MSCF2, page 18-8
• PFC1 and PFC2 General Restrictions, page 18-9
• Unsupported Features, page 18-9
PFC2 with MSCF2
In systems with PCF2 and MSFC2, IP multicast Layer 3 switching is not provided for an IP multicast
flow in the following situations:
• For IP multicast groups that fall into the range 224.0.0.* (where * is in the range 0 to 255), which
is used by routing protocols. Layer 3 switching is supported for groups 225.0.0.* through 239.0.0.*
and 224.128.0.* through 239.128.0.*.
Note Groups in the 224.0.0.* range are reserved for routing control packets and must be flooded
to all forwarding ports of the VLAN. These addresses map to the multicast MAC address
range 01-00-5E-00-00-xx, where xx is in the range 0–0xFF.
• For PIM auto-RP multicast groups (IP multicast group addresses 224.0.1.39 and 224.0.1.40).
• If the SPT bit for the flow is cleared when running PIM sparse mode for the interface or group.
• For packets with IP options. However, packets in the flow that do not specify IP options are hardware
switched.
• For source traffic received on tunnel interfaces (such as MBONE traffic).
PFC1 with MSFC or MSCF2
In systems with PFC1 and MSFC or MSFC2, IP multicast Layer 3 switching is not provided for an IP
multicast flow in the following situations:
• For IP multicast groups that fall into these ranges (where * is in the range 0 to 255):
224.0.0.* through 239.0.0.*
224.128.0.* through 239.128.0.*
Note Groups in the 224.0.0.* range are reserved for routing control packets and must be flooded
to all forwarding interfaces of the VLAN. All these addresses map to the multicast MAC
address range 01-00-5E-00-00-xx, where xx is in the range 0–0xFF.
• For PIM auto-RP multicast groups (IP multicast group addresses 224.0.1.39 and 224.0.1.40).
• For flows that are forwarded on the multicast-shared tree (that is, {*,G,*} forwarding) when the
interface or group is running PIM sparse mode.
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