Siemens S223 PIM-SM Protocol Independent Multicast-Sparse Mode, Displaying Igmp Snooping Table

User Manual	UMN:CLI
SURPASS hiD 6615 S223/S323 R1.5

9.2.9Displaying IGMP Snooping Table

To display an IGMP snooping table, use the following command.

Command	Mode	Description
show ip igmp snooping groups
[IP-ADDRESS]
show ip igmp snooping groups	Enable
port [PORTcpu]
	Global	Shows a configuration.
show ip igmp snooping groups
	Bridge
vlan VLANS
show ip igmp snooping groups
mac-based

9.3PIM-SM (Protocol Independent Multicast-Sparse Mode)

IGMP is the protocol to help multicast communication between switch and host, but PIM is the protocol for multicast communication between router and router. There are two kinds of PIM, PIM-DM (Protocol Independent Multicast–Dense Mode) and PIM-SM (Pro- tocol Independent Multicast–Sparse Mode), the hiD 6615 S323 supports PIM-SM only.

Protocol of dense mode can send information about data packet and member to interface, which is not connected to multicast source or receiver, and multicast router saves con- nection state to all the nodes. In this case, when most hosts are belonged to multicast group and there is enough bandwidth to support flow of controlling message between constituent members, these overheads are acceptable, but the other cases are inefficient.

Contrary to dense mode, PIM-SM receives multicast packet only when request comes from specific host in multicast group. Therefore PIM-SM is proper when constituent mem- bers of group are dispersed in wide area or bandwidth used for the whole is small. Sparse mode is the most useful on WAN and can be used on LAN. For standard of PIM-SM, you can refer to RFC 2362.

RPT and SPT

RP (Rendezvous Point) works in a central role for PIM-SM. Viewing the below chart, mul- ticast packet is transmitted to D as RP from A as source, through B and C. And D (RP) transmits multicast packet after receiving join message from E or F. That is, all multicast packets are transmitted with passing through RP (Rendezvous Point). For instance, even though F needs multicast packet, the packet is passed through『A→B→C→D→C→F』, not『A→B→C→F』.

Like this, route made with focusing on RP is RPT (Rendezvous Point Tree) or shared tree. There is only one RP in one multicast group. RPT has (*, G) entry because receiver can send a message to RP without knowing source. “G” means multicast group.

A50010-Y3-C150-2-7619 303