Cisco Catalyst 3750-X User Manual

48-2
Catalyst 3750-X and 3560-X Switch Software Configuration Guide
OL-21521-01
Chapter 48 Configuring IP Multicast Routing
Understanding Cisco’s Implementation of IP Multicast Routing
Understanding Cisco’s Implementation of IP Multicast Routing
The Cisco IOS software supports these protocols to implement IP multicast routing:
• Internet Group Management Protocol (IGMP) is used among hosts on a LAN and the routers (and
multilayer switches) on that LAN to track the multicast groups of which hosts are members.
• Protocol-Independent Multicast (PIM) protocol is used among routers and multilayer switches to
track which multicast packets to forward to each other and to their directly connected LANs.
• Distance Vector Multicast Routing Protocol (DVMRP) is used on the multicast backbone of the
Internet (MBONE). The software supports PIM-to-DVMRP interaction.
• Cisco Group Management Protocol (CGMP) is used on Cisco routers and multilayer switches
connected to Layer 2 Catalyst switches to perform tasks similar to those performed by IGMP.
Figure 48-1 s
hows where these protocols operate within the IP multicast environment.
Figure 48-1 IP Multicast Routing Protocols
According to IPv4 multicast standards, the MAC destination multicast address begins with 0100:5e and
is appended by the last 23 bits of the IP address. For example, if the IP destination address is 239.1.1.39,
the MAC destination address is 0100:5e01:0127.
A multicast packet is unmatched when the destination
IPv4 address does not match the destination MAC
address. The switch forwards the unmatched packet in hardware based the MAC address table. If the
destination MAC address is not in the MAC address table, the switch floods the packet to the all port in
the same VLAN as the receiving port.
This section includes information about these topics:
• Understanding IGMP, page 48-3
• Understanding PIM, page 48-4
• Understanding DVMRP, page 48-9
• Understanding CGMP, page 48-9
Host
Host
PIM
IGMP
CGMP
DVMRP
Internet
MBONE
Cisco Catalyst switch
(CGMP client)
44966

Cisco Catalyst 3750-X Specifications

General

Switching Capacity	160 Gbps
Stacking Bandwidth	64 Gbps
Max Stacking Units	9
Layer Support	Layer 2 and Layer 3
Form Factor	Rack-mountable
DRAM	256 MB
Flash Memory	64 MB
Model	Cisco Catalyst 3750-X Series
Ports	24 or 48 10/100/1000 Ethernet ports
Uplink Interfaces	4 SFP or 2 SFP+
Features	StackWise Plus, EnergyWise
Image	IP Base or IP Services
Operating Temperature	0 to 40°C
Operating Humidity	10 to 85% noncondensing